Run webinar with more than one webcam I'm trying to create a little home office webinar setup. I'd love to use more than one camera. One to point at my face, and another to point at a drawing, or diagram I'm making.

I will likely be using webrtc as a platform, but would love it if I could set it up to work with Skype and Google hangouts and such.

Is there a way to have two usb webcams plug into a switcher, and then just click a button or hit a switch and change which camera feeds into my webinar program? Ideally there would be black screen while switching.

Webcams live in the universe of being devices plugged into computers, and switchers live in the universe of standard video sources being plugged into them.  These two universes only talk to each other via specialized interfaces (if at all).

Happily, there exists software that gives you switcher-like functionality as a software package for your computer.  One such package is manycam.  There are others you can find.

Trying to get webcam video out of your computer as video, into a switcher, then back into your computer so that it can be webcast is about 3x more difficult than it needs to be.  And it requires a lot more space on a physical desktop.


Convert FFMPEG Waveform Back to audio I'm trying to convert an audio file to an FFMPEG waveform, train it in HyperGAN, and produce an image file to convert to an audio file. What I'm asking is if there is a way to convert a waveform image back to an audio file without any loss of quality (basically, if you were to hash the original and the converted one, it would be the same hash), and if FFMPEG is the correct tool to use. Currently I have a batch script to go through all my audio files and convert them to images (ffmpeg.exe -i %1 -lavfi showwavespic=s=1024x800:colors=0971CE %1.png), but I can't convert them back to audio files, which defeats the purpose of what I'm doing.

EDIT: FFMPEG converts a 5mb audio file to a 32kb image, so I don't think it would convert back. Is there anyway to make it more detailed?

FFmpeg can't do this.

Even theoretically, the method seems unsound (no pun intended). Audios are typically sampled at 40K+ Hz per second. Max image dimension in ffmpeg is 65K. So even at that size, one can barely represent 1.5 seconds of audio at full sampling resolution. Once you go lower and rely on interpolation, your output quality will start to degrade, as your reconstruction gets coarser.


Broadcasting video and bandwidth issue I need to broadcast on the Internet weekly live video events.
One attempt was made with Skype and it worked pretty well, but it was only with one user. We expect 50 users and we have a low bandwidth here so I guess Skype won't be a solution.

What do you recommend for broadcasting live video events to 50 people with low bandwidth from the video source ? Free solutions are preferable.

Thanks!

If you have at least 300-500kps of upload bandwith available you can push an rtmp stream of your live event to a CDN like youtube, dailymotion, livestream ...

In terms of software I already used:

Livestream, which provides among other things a tool called procaster with which you can broadcast your desktop, or a section of your desktop. You can even broadcast a capture of your skype window ! ( it will not be very beautiful, but it works ). Livestream also has many tools which allow to make a chat during your live event with the viewers of the event.
Flash Media Encoder (aka FME ), which is a free tool provided by Adobe, which will encode to rtmp any video camera connected to your computer. You can then push it to a CDN like YouTube or DailyMotion.

All of this is free of charge, with sometimes some limits on the number of simultaneous viewer, and/on an ad-supporting scheme which will play an advertisement before your live video.


Getting DaVinci 16.2 Resolve to Work with Intel Gen 4 Graphics I am currently trying to give DaVinci a try for my video editing needs. However, I am running into issues, which seem to be graphics card related.

It crashes like this (from the logs):

[0x7fb0b796c000] | Main                 | INFO  | 2020-04-06 13:25:43,873 | Running DaVinci Resolve v16.2.0.055 (Linux/Clang)
[0x7fb0b796c000] | Main                 | INFO  | 2020-04-06 13:25:43,874 | Updating display GPU information...
OpenCL error -1001: 'Unspecified Error', GPUPropertiesUtilUnix.cpp:338.
terminate called after throwing an instance of 'ReactorGPU::GPUException'

==========[CRASH DUMP]==========
Please send this to support:

#TIME Mon Apr  6 13:25:43 2020 - Uptime 00:00:00 (hh:mm:ss)
#PROGRAM_NAME DaVinci Resolve v16.2.0.055 (Linux/Clang)

/opt/resolve/bin/resolve() [0x54a0029]
/opt/resolve/bin/resolve() [0x549f81a]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x12890) [0x7fb0c1d4e890]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0xc7) [0x7fb0bfad2e97]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x141) [0x7fb0bfad4801]
/opt/resolve/bin/resolve(_ZN9__gnu_cxx27__verbose_terminate_handlerEv+0x15d) [0x720748d]
/opt/resolve/bin/../libs/libc++abi.so.1(+0x22086) [0x7fb0f3e58086]
/opt/resolve/bin/../libs/libc++abi.so.1(+0x21a27) [0x7fb0f3e57a27]
/opt/resolve/bin/resolve() [0x1fabdbc]
/opt/resolve/bin/resolve() [0x1fab589]
/opt/resolve/bin/resolve() [0x1fa539c]
/opt/resolve/bin/resolve() [0x1f727cc]
/opt/resolve/bin/resolve() [0x1f6f8de]
/opt/resolve/bin/resolve() [0x1f6e33e]
/opt/resolve/bin/resolve() [0x1f6dbe8]
/opt/resolve/bin/resolve() [0x1f8299a]
/opt/resolve/bin/resolve() [0x1f698ff]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7) [0x7fb0bfab5b97]
/opt/resolve/bin/resolve() [0x1f68b7d]
Signal Number = 6

The CPU and Graphics card on this machine are as follows:

  *-display
       description: VGA compatible controller
       product: Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 06
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:32 memory:f7800000-f7bfffff memory:e0000000-efffffff ioport:f000(size=64) memory:c0000-dffff

     *-cpu
          description: CPU
          product: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
          bus info: cpu@0
          version: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
          slot: CPUSocket
          capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm cpuid_fault invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt dtherm ida arat pln pts md_clear flush_l1d cpufreq
             slot: CPU Internal L1
             slot: CPU Internal L2
             slot: CPU Internal L3

More specifically, the graphics card is a Gen 4 Intel 4600.

Does anyone know if it is possible to get DaVinci working on this system? If so, how should I troubleshoot this issue?

Black Magic Design have recently released Resolve version 16.2.1 with "Improved stability on Windows systems with Intel graphics" - which may help, but generally speaking support and performance on Integrated CPU's has always been limited. I can run DR on my Laptop with an Intel HD 520, but only for very basic & slow editing.

You also did not say when it crashes. i.e. At startup / playback / edit, and what media was being processed (if any).

Minimum system requirements for Windows:
Windows 10 Update
16 GB of system memory. 32 GB when using Fusion
Blackmagic Design Desktop Video version 10.4.1 or later
Integrated GPU or discrete GPU with at least 2GB of VRAM
GPU which supports OpenCL 1.2 or CUDA 10
NVIDIA/AMD/Intel GPU Driver version


DaVinci Resolve can't deliver 1920x1080 videos I'm new to DaVinci Resolve, and new to video editing too.
I used the newest version of DaVinci Resolve 16. I used OBS Studio to record some game/desktop footage at 1920x1080 and 30 fps. I then imported said footage into DaVinci with no issues and edited it. Everything was normal. However, after rendering, the result looks wrong (see the image below)

The output video canvas seems to be 1920x1080, but the actually image is squeezed.

My project settings for the timeline are:
- 1920x1080.
- Pixel ratio is square -- I have a few options (square, 16:9, 4:3 and cinema), but when I choose 1920x1080, the 16:9 and 4:3 checkboxes stay dark and I can't select them.

I tried also to change the "Clip attributes", which include PAL 16:9 and NTSC 16:9. None of it worked.
I used the "Youtube 1080P" rendering option preset.

I don't think it's a limitation of the free version.  Check all the project and system settings in Davinci. There are a lot of them - maybe one of them is set to something other than 1920x1080


iMovie workflow for creating different versions or snapshots? While using iMovie, I want to easily create snapshots of my project so that I can easily go back in time and grab things that I need.

For example, if I'm making large scale changes, and I accidentally messed up a clip or a nice transition, I want to be able to go back in time to grab the version of the clip before it was messed up.

In its default state, iMovie has you working on one single version of a project, and your only way to go back in time is by using the undo feature. However, this is not preserved between app launches, and probably has a limit.

I know I could copy an entire library, but that would take up a ton of disk space as all the videos would be copied too.

TL;DR

Use separate iMovie Libraries for each video project.
Duplicate projects for each version.

This is the current workflow I've come up with:

Very importantly, create a separate iMovie Library for each of your video projects (not to be confused with a Project in iMovie). This will make versioning and backup much easier. By default, iMovie has you saving everything in one giant Library, making it both hard to find what you need, but also hard to backup or share a specific project.
Create a new Project, and call it master. This will be the only Project you ever edit directly and will always represent the latest changes.
Start editing your Project. Once you get into a state where you want to "save" it as a version, go to Projects, and duplicate master. Rename it to v0.1 and optionally add a description. E.g. v0.1 - initial transitions done, still missing credits.
Continue working on master and creating more versions as you go along. E.g. v0.2 - before making large scale changes to the contrast of all the clips.
Once you're at a point where you want to share your video (e.g. via uploading to YouTube), create a major version number (E.g. v1.0). This will make it really easy to come back to the "YouTube" edit of your video, for example.
If you continue making changes, continue using the same versioning scheme to make v1.1 - Credits fixed, for example.

By duplicating Projects within the same Library, you save a ton of disk space since each project copy is lightweight and doesn't copy over all the video files.


Remove echo when recording in say, a hallway Sorry if this is the wrong site to ask this question, with it not being strictly about video.

Say I’m conducting an interview in a hallway or similar environment. There are a lot of flat surfaces, maybe an uncarpeted floor, this is going to produce a lot of echo and sound distortion. A purpose-made room or studio isn’t an option as the interviews are supposed to be “of the moment”. How would I go about eliminating echo?

I can’t go around the whole location putting up blankets to dampen the echo, so would I be looking at some sort of attachment on the camera microphone, i.e. a windsock (or similar attachment if a windsock isn’t appropriate)?

The attachment you are looking for is called a lav mic, though sometimes it can be a hand-held shotgun mic, too.  Sound intensity decreases as the square of distance and echoes decay exponentially.  The trick to eliminating the echo is to get the mic sufficiently close to your sound source that the original source is 10dB to 20dB louder than the environmental echo.  If you see how close a news reporter holds a mic up to a subject when interviewing them in the moment (and sometimes in a hallway), do that.

There's nothing you can put on the microphone that will solve the echo problem.  The only way to solve it is with proper distance (which is a function of proper distance ratios).


what's a good basic app to edit stop motion video? Possible Duplicate:
  How can I align photos for stop motion?
  Command Line Tool for Converting Image Sequence to Quicktime .mov Video

Want to do a project with my kids over the holidays and create a stop motion video using their large assortment of dolls.  We are good with taking the shots but wondering what a good editing app would be to put it all together.

Personally, for a quick-and-dirty solution, I use iMovie. You put all the stills into a new project, then you highlight them all, choose clip settings and disable the Ken Burns effect, and put the duration of the photo to 0.1 seconds (This is the fastest iMovie can handle).


Size of YouTube Subscribe Circle and Video Rectangle I need to design custom YouTube End Screen.

What's the standard size of Subscribe Circle and Video Rectangle?

When using brand identifiers such as the YouTube Logo, you want to check what guidelines the brand has on using their brand resources. A quick Google search yields the official Brand Resources guideline by YouTube. Here you will find all you need:

  Minimum size

  The word "YouTube" should always be easy to read. So in digital
  content the Logo should never appear smaller than 24dp in height.

  The minimum size for applying the Logo in print is 0.125 in/3.1 mm in
  height.

Check the linked page for more details on the usage of the Logo.

Sidenote: Since YouTube belongs to Google, they use the terminology of Google's Material Design guidelines. dp stands for Density-independent pixels, you will find an explanation on that on the Material Design website.


Should I use a GoPro Hero 3 Black for recording drama? My school's drama department is looking for a camera to record our plays/musicals.

I have looked and looked for a good camera that

Records in 1080p at 30fps
Has a mic-in port so we can connect our sound board to it to record directly onto the video from the tech booth.

I think the GoPro might work. It records at 1080p 60, 48, 30, or 24 fps, and has a mic-in. Would this work?

The tech booth is elevated and is in the back of the auditorium. I wouldn't need to zoom as I can crop it and scale it in post (which I think we will export at 720p) and I don't want it to look fish-eyed or distorted. Would the Narrow option work?

What I really want answered is, Should I use the GoPro Hero 3 Black or is there a better camera to use ($400 or less)?

The GoPro is really more designed as a small, rugged, action camera.  It really isn't designed for recording a theater production and you would be able to get much better quality out of any number of camcorders in that price range.  You really want something with an optical zoom on it.

Either something like a Canon T3i or T2i would probably handle what you need.  Alternately, Panasonic makes some pretty good video cameras in that price range.

It is also worth noting that the GoPro has no screen so you would need to buy a separate screen to know what it is that you are actually shooting so that you could aim it.  There is one available from GoPro, but it adds around $80 to the cost.


Shooting with a camera and then pausing while recording We're shooting basketball videos, and I would like to be able to Pause/Rewind while continuing to record, so I can show the coaches of the team the video, while the players are still playing.

Is there something in Adobe Premiere that will allow you to do this, or will I need to buy a PVR or something?

We currently are looking to buying a new camcorder, and getting the entire setup created. Basically we want to be able to record all of our games straight to a computer via a capture card or direct Firewire out of the camera, and then be able to Pause/Rewind/Scrub through the video, but when we are pausing and scrubbing, we still need to be able to catch back up to "Real Time", basically like a DVR in a TV.

It doesn't sound like thee is a cheap or easy way to do what you want to do.
I use premiere a lot and.  There are mutlicam features for Premiere that allow you to sync to tracks and edit them easily, not to do live recording and playback at the same time.
If you stop and start the recording on lulls in the game where nothing is happening you will generate files that can be played back while the computer is recording the next file.

Also
Most computers video cards have an HDMI out, and can output to two monitors.
wire one output through a PVR and use that to rewind etc.  I don't have any experience with a pvr but that might work.


restart ffmpeg job from failure Is there a common technique or some sort of strategy for restarting a failed transcoding job from where it had left off when it crashed (or stopped for whatever reason)?

For example, if I have a 2 hour transcoding job and it fails/crashes at 1 hour and 59 minutes, is there some way I can just do that last minutes worth of work and use the progress I already had assuming the partially transcoded file is still available?

A direct option to resume encoding is not available.

And as for manually restarting encoding, that's also not possible. Two reasons:

1) when transcoding to a typical container like MP4, the index is written after encoding is completed. There will be no such index in a partial file if the process died unexpectedly, and so the existing file cannot be parsed.

2) If you cannot accurately identify the last uncorrupted frame encoded in the partial file, your join will not be seamless.

That said, there is a tedious way this can be done. The method hinges on using the segment muxer. You encode to MPEG-TS format but segment the output as it is being generated. Should the job fail, you examine a few attributes and resume encoding based on that data. Finally, you join all segments together.

Step 1: Encode and segment

For best results, audio and video should be done separately. In fact the audio can be done without segmenting since it will encode much faster

ffmpeg -i in.mp4 -c:a aac -vn job-audio.mp4

And for video

ffmpeg -copyts -start_at_zero -ss 0 -i in.mp4 -c:v libx264 -an
       -f segment -segment_time 0.01 -segment_time_delta 1
       -muxpreload 0 -muxdelay 0 -mpegts_copyts 1
       -segment_start_number 0 -segment_list files.ffcat
job-video%d.ts

Each segment above will contain one GOP, so no frames in a segment rely on frames in other segments for playback.

Step 2 Identify resume point

Suppose the job fails while creating segment #5.

First, you run

ffprobe "in.mp4" -show_entries stream=codec_type,start_time,duration -of compact

This will produce a readout like this

stream|codec_type=audio|start_time=0.000000|duration=356.309333
stream|codec_type=video|start_time=0.040000|duration=356.360000

Note the start time for the video stream.

Now, run it for the first and the last (incomplete) segment

ffprobe "job-video0.ts" -show_entries stream=codec_type,start_time,duration -of compact

stream|codec_type=video|start_time=0.080000|duration=10.000000

You see that there's a positive offset of 0.04 w.r.t the MP4 video stream. Let's call this the initial offset value

Now, for the last stream

ffprobe "job-video5.ts" -show_entries stream=codec_type,start_time,duration -of compact

stream|codec_type=video|start_time=20.080000|duration=4.320000

Step 3 Resume encoding

So, now you run

ffmpeg -copyts -start_at_zero -ss {start_time of last segment - initial offset} -i in.mp4 -c:v libx264 -an
       -f segment -segment_time 0.01 -segment_time_delta 1
       -muxpreload 0 -muxdelay 0 -mpegts_copyts 1 -initial_offset {initial offset}
       -segment_start_number {index number of last segment} -segment_list files-resume.ffcat
job-video%d.ts

Step 4 Join segments

You'll have multiple .ffcat files - from the first run and all resumed runs. Copy over the entries from all secondary runs and append them to the first file. Avoid duplication.

Run

ffmpeg -f concat -i files.ffcat -i job-audio.mp4 -c copy full.mp4


How to concatenate two mxf files with ffmpeg, preserving both audio channels? I have mxf files which went over the 2G limit, so were split up in the camera to produce two mxf files.  They have two audio streams, one from each mic, like this:

Duration: 00:10:01.60, start: 0.000000, bitrate: 27165 kb/s
Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, bt709), 1440x1080 [SAR 4:3 DAR 16:9], max. 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn, 59.94 tbc
Stream #0:1: Audio: pcm_s16le, 48000 Hz, 1 channels, s16, 768 kb/s
Stream #0:2: Audio: pcm_s16le, 48000 Hz, 1 channels, s16, 768 kb/s

I know how to concatenate them with ffmpeg:

ffmpeg -i "concat:a01.mxf|b02.mxf" -y -c copy result.mxf

But, this combines the audio streams and produces a file with just one, merged stream.

I also know how to split out the individual audio streams into individual files:

ffmpeg -i a01.mxf -map 0:1 -vn one.aiff
ffmpeg -i a01.mxf -map 0:2 -vn two.aiff

Grabs the streams and correctly transfers them across untouched.

My question is, how to do this for the split up mxfs?  I could rip their sound, then join the video, then put the sound back in, but it seems really unnecessary, and there should be a way to use a big -map command to do all of this.

Apparently by default ffmpeg only copies one stream of each type.  To tell it to copy all streams, you need -map 0

So, this does it:

ffmpeg -i "concat:a01.mxf|b02.mxf" -y -map 0 -c copy result.mxf


Why do SRT subtitles fail to appear in my MP4 videos on iPhones? I'm using videojs in an HTML page to publish a video with VTT captions. Problem is: iPhones do not play the mp4 in the videojs player - it renders the full videojs player, but when you click the Play button, it opens the mp4 in it's native player (QT player, presumably). This is normal behaviour for video on iPhones - but at that point I lose my captions, which are inserted in the videojs player through css.

So I ran the MP4s through Handbrake with imported .srt files. In my local VLC player, the captions appear. But when I put the same files (MP4 + SRT) in the same directory on my web server, the subtitles do not appear on the video in iPhones. In fact, the subtitles - or any subtitles option - also do not appear in the native players of desktop Firefox, Chrome or IE 11 (which uses a QT plugin for video).

It's not a problem of coding (used UTF-8) or server configuration - if I insert two <tracks> in the videojs <video> element - one the vtt file, one the srt file - both play, together, in the videojs player.

Update with answer

It can be done. Run your source files through Handbrake, after importing the subtitle files you want. Then export as Mp4. I've read (a) you should put the SRT file/s in the same folder as the Mp4 on your server, and (b) the SRT should have the same name as the mp4. But (a) is probably wrong (in a text-editor, you can see the subtitles have been coded into the mp4 by Handbrake) and (b) is definitely wrong - two different language SRT files will obviously have different file names.

Testing... On iPhone, a little speech bubble appeared on the right side of the QT player control bar when it loaded my MP4. Tapping that popped up the two subtitle language options. So, it worked. But it only worked because first my tester had to enable "closed captions" in his iPhone's:

Settings > General > Accessibility > Subtitles & Captioning > Closed Captions + SDH

In other words, an extra chore for users and the result is crappy-looking subtitles anyway. And all this because, unlike Samsungs and most other mobiles I've tested on, the iPhone overrides the videojs player and plays your videos in Apple's own Quicktime player.


ffmpeg: Placing an overlay over multiple images I am trying to overlay a png image onto a series of images (a few hundred images), I will later take this series of images with the overlay and construct a movie out of the series of images. I don't know too much about ffmpeg and I have just recently started playing with it for converting and editing media files but I have found something that works for combining the png with one tif image:
ffmpeg -i my.png -i my.tif -filter_complex "[1][0]scale2ref[i][m];[m][i]overlay[v]" -map "[v]" -map 0:a? -ac 2 output.tif
This is what I have so far, which allows me to overlay my png on a single tif image. I would like to do this for every single tif image that I have in my folder (hundreds) of tif images.
Is there a way to instruct ffmpeg to do such a process?
Thanks

If all TIFFs have the same properties, and are named sequentially like image0001.tif, then you can use
ffmpeg -i image%04d.tif -i my.png -filter_complex "[1][0]scale2ref[i][m];[m][i]overlay" out%04d.tif

This will generate images with the overlay named as follows
out0001.tif
out0002.tif
...


What kind of storage for digital footage? I've got a bunch of usb external hard drives, but I don't trust them for storing digitised footage. I will have potentially up to 3 TB of footage after digitising. USB can be slow for transferring large files. Is there a faster alternative? and how do I know what I buy is reliable? E.g. is it better to have 3 1 TB disks or 1 3 TB disk? Is it better to go for an internal hard drive in a PC or an external disk drive?

Don't trust any hard drive to be reliable! Always backup your footage, you can not trust any HDD, doesn't matter how reputable the manufacturer is. There are always monday batches. HDDs WILL fail at some point, so ALWAYS make backups.
Bear in mind that you might find a RAID solution nice to use but that's not a real backup, backup drives are disconnected and are not running with your "live" drive, otherwise you might end up with all your drives failing together, including your backups.

I recommend going for at least 2x3TB drives, they have a lot better price per GB than 1TB drives. Though 1TB drives tend to last a tad longer on average but thats not worth the much higher price in my opinion. If you want to invest more for higher product life, don't buy standard desktop drives but instead a workstation or server HDD. For Western Digital (WD) that would be the Red/Black/Purple series. Seagate has a few 24/7 Surveilance HDDs that are also more reliable.

In terms of speed. I'm guessing you are using USB 2.0. An alternative is USB3.0, the speed of that exceeds the read and write speeds of any HDD. If you are a Mac user you also have Thunderbolt in most newer products but external HDD cases for that are a hell lot more expensive than USB 3.0 cases but they have the advantage of daisy chaining, which means you can connect many external drives to one port without a hub if you need multiple drives connected at the same time.

In terms of what is better, external or internal. For HDDs that doesn't really matter anymore in terms of speed, as long as you get a case with a quality controller and dont use USB 2.0 or Firewire. It depends on what suits you better. A case is of course more portable but there are also hot swap cages for backups that are installed like DVD drives.
Choose what you prefer.

And a general advice, never buy a complete solution where you buy a hard drive already enclosed in an external case. You do not know what you get and they are barely cheaper than getting your own case and installing the HDD yourself in a few seconds.


Replacing/changing video background How could I replace the background of a video such as the one in the picture

to a bright white? I have iMovie, is it of any use here?

That's a tricky one since the background color is the same as the shirt shes wearing. This can be achieved Manually by masking your subject frame by frame, if there is no much movement and duration is little then this shouldn't be a problem, although you might have some difficulty with the hair.
Note: masking should not be very accurate in this case, make a fast one then feather it and increase the brightness of the layer behind "background" until it becomes bright white and see if you like the result.


How to capture / upload videos at scheduled times Let's say there is a conference and there are several hour-long talks by speakers.

Is there a way to setup a stationary camera that will

Record specific talks (say the talks that start at 8:00a, 10:00a, 1:00p and 4:00p)
Upload to a video hosting service(YouTube, ustream, livestream etc.)
Never run out of space (because it records/uploads and deletes after successful upload)?

Is it possible to schedule recording start/stop times?If not, one should be able to start/stop recordings with one of those cameras that have wifi enable remote controls right?

Would live streaming be a better option since most video hosting services record the stream anyway?

The more I thought about my requirements the more I was convinced that I needed a wifi enabled "security" camera setup than an action cam setup.

I'm giving dropcam a try. It seems to satisfy all my requirements.

Broadcast without any additional equipment
Schedule recording times remotely from anywhere
Broadcast is automatically recorded in the cloud for 7 to 30 days (subscription req.)

I just hope the video quality is good enough.


ffmpeg: make a video with multiple input files and formats I am trying to make a video with multiple input files.
I have a bunch of PNG files and mp4 files and I want to create a video for the duration of my audio file body.mp3

The video should be made using multiple inputs.

file 000000.PNG for duration 17.56
file 01.mp4 (duration ~4.0)
file 100074.PNG for duration 6.12
file 02.mp4 (duration ~4.0)
file 200074.PNG for duration 7.84
file 03.mp4 (duration ~4.0)
file 300074.PNG for duration 11.88

The total video will have only one audio from body.mp3. Assuming body.mp3 duration is equal to all the inputs duration combined (+/- 2.0)

Could you please show me how to achieve this?

Edit: Same resolution for all the input files and same frame rate in all the *.mp4 files. Some times, I may have 04.mp4 and 400074.PNG also.

Let's say the framerate of the MP4s is 30, then you would use

ffmpeg -i body.mp3
       -framerate 30 -loop 1 -t 17.56 -i 000000.PNG
       -i 01.mp4
       -framerate 30 -loop 1 -t 6.12  -i 100074.PNG
       -i 02.mp4
       -framerate 30 -loop 1 -t 7.84  -i 200074.PNG
       -i 03.mp4
       -framerate 30 -loop 1 -t 11.88 -i 300074.PNG
-filter_complex "[1][2][3][4][5][6][7]concat=n=7:v=1:a=0[v]"
-map "[v]" -map 0:a -pix_fmt yuv420p out.mp4

(All in one line; use single-quotes if you're on linux/OSX)


Why do we still shoot 23.976 if NTSC and PAL have been replaced? I watched this video and had loads of questions.

If NTSC ran into problems with colour and therefore slowed down 30 to 29.976, and 24 to 23.976, why didn't PAL have the same problems and slow down 25 by 0.1%?
If PAL and NTSC have been replaced DVB-T, ATSC, ISDB-T, DTMB, why do we still talk about them everywhere, and they show up in settings on cameras? So do the new standards display true 24 and 60 fps? What about 25 fps in PAL regions? Do PAL and NTSC regions still exist?
So, what is the point of my camera shooting 23.976? Why don’t we all shoot 24, and let NTSC TV slow down the playback at 0.1%? Alternatively, why not just shoot true 24 because all modern TVs can display it anyway? Is it something to do with the electronics in the camera?
The video says delivering at 24 is obviously for DCP projection at digital theatres. So does that mean that if I shoot and deliver at 23.976, it won’t project properly? Why don’t we all shoot and deliver true 24 if TVs can display it anyway? Why is there still this issue with 24, 25, 30 fps, depending on NTSC/PAL regions of 50/60Hz?
So what happens if I shoot 23.976 and deliver at 24? Will there be duplicated frames? Or does it become shorter in length? Vice versa, what if I shoot true 24 and deliver at 23.976? Are there skipped frames? Or does it become longer? Likewise, what about compatibility with 25 fps? Say, if 23.976 or 24 was to be broadcast in PAL regions, which you mention have been replaced?

23.976fps still exists because it's a standard. Cameras became designed to shoot it, non-linear editing software suites were designed to edit them, and devices were designed to play them. Even though NTSC went away, cameras still shot in 23.976fps. Even if they could shoot a flat 24fps, it causes issues in the edit room.
Putting 24fps footage on a 23.976fps timeline will have some issues but can be mitigated by being slightly slowed down or with pulldown. However, you will run into issues with multi-camera setups and syncing audio, hence this
discussion about editors complaining about audio sync drifting.
In the end, 23.976fps still a standard because if cameras switched to 24fps, it would cause issues in the edit room, and if editors used 24fps timelines, it would give pretty much everybody after them in the pipeline a hard time. Even if everybody could adapt to 24fps, most delivery standards are designed for 24fps anyways, so it'd have to be converted back to 23.976fps at some point in the pipeline, therefore it'd make it much less of a hassle to just shoot at 23.976fps anyways.


Change the timecode with ffmpeg in the middle of the track? I know you can change the timecode of a file with FFmpeg with the option –timecode. This modifies the whole timecode of the file starting from the  -timecode added.

Can you change the timecode with FFmpeg in the middle of the file? Jumping to another timecode (always in the future). This can be useful with the –concat option. Merging a bunch of files into a unique file. Reflecting the actual time every isolated file was recorded.

Depending on your final use case, a non-standard way to deal with that would be to keep the original TC as LTC (audio TC) on an additional track. Concatenating clips would then preserve the original TCs on that separate track.


FFmpeg: What is an acceptable value for the q= parameter? I'm trying out encoding video with ffmpeg using x264 on a NAS machine with a 2.4 GHz processor. This yields a terminal output that has a high number in the q= parameter:

frame=  236 fps=0.2 q=29.0 size=    1038kB time=00:00:08.82 bitrate= 963.4kbits/

When I encode using x265 on my standard computer, I get something that looks like this:

frame=67350 fps=0.7 q=-0.0 size=  416991kB time=00:37:28.41 bitrate=1519.3kbits/

It is my understanding that q= stands for quality, and should probably be as close to 0 as possible, while a low number close to q=31 indicates poor quality and that ffmpeg has difficulties reaching an acceptable bitrate.

Is this something specific to x264 or is it that my settings for the NAS machine are too demanding? The video sources are 1080p at 30 fps.

ffmpeg -i "$i" -c:v libx264 -preset veryslow -crf 23 -af "volume=25dB, highpass=f=200, equalizer=f=50:width_type=h:width=100:g=-15" -c:a aac -strict experimental -b:a 192k

Should I be concerned about this, and what can be done about it?

Your rate control mode is CRF, so there's no target bitrate to hit. And for a value of 23, QP of 29 is what I normally see used. Ultimately, the test is whether the video looks acceptable.


How to reverse video in different software packages One of the basic edits one can make to a video is reversing it such that it plays backwards.
The goal of this community wiki is to show beginning users how to reverse footage with different video editors.

When adding answers, please try to make the guide as easy as possible as this is aimed towards beginning users.

List of software in alphabetical order

After Effects
Premiere Pro
Vegas Movie Studio & Vegas Pro

After Effects

There are three steps involved when you want to reverse footage in After Effects.

Import the footage
Go to File -> Import -> File... select your footage and click Open
Create new composition
In the Project Panel drag your footage to the new composition button as shown in the image below:

Reverse the footage
Now in the Composition Panel right click on your footage and go to Time -> Time-Reverse Layer as shown in the image below:

Now your footage is reversed and you only need to export it with the settings you desire by clicking Composition -> Make Movie...


Special effects/post processing to make a black-colored light I had this idea for an effect and I wanted to know if something like this has been done and if so how to do it:

Goal:

I want a lighting effect for an action scene where I will have an area start lighting up, while I would like to simultaneously have another area start darkening in a similar manner, all in a (relatively) lit environment. I want an effect that looks basically in all ways like a light, but its something like a black-colored light that paints its surrounding black in a light-like way.

Idea:

Basically I wanted to know if there is any way I can do some kind of post processing where I can use an LED as a green screen of sorts for the darkening effect. So wherever the LED is shining more or less maps to some kind of darkening effect/transformation.

I've got another idea, but it's a little kooky.  You light the WHOLE SCENE with spotlights - the fewer the better.  On the key spotlight, you add a gel that has an opaque black circle on it.  Then as you move that around, that section of darkness will pass over parts of the set/props/actors.

For a more focused spot, you could use a bright digital projector to project the image of a black circle on a white field.  Focus it based on the parts of the scene you're moving it across.


Old webcam recorded video not playing I have this video (length 1-2 min) recorded on Dell webcam 3-4 years ago. It played smoothly at that time. Now when I play it, for first 40 seconds it plays well but after that video goes blank and audio stops. Video continues to move forward but without video and audio, just blank .

Is there by any chance I can recover this video? If yes, how?
It's an AVI file, 550 MB.

Codec -

Video
ID                             : 0
Format                         : RGB
Codec ID                       : 0x00000000
Codec ID/Info                  : Basic Windows bitmap format. 1, 4 and 8 bpp versions are palettised. 16, 24 and 32bpp contain raw RGB samples
Duration                       : 1mn 34s
Bit rate                       : 47.1 Mbps
Width                          : 640 pixels
Height                         : 480 pixels
Display aspect ratio           : 4:3
Frame rate                     : 30.000 fps
Bit depth                      : 8 bits
Bits/(Pixel*Frame)             : 5.114
Stream size                    : 533 MiB (97%)

To me sounds like a lack of original codecs. Why don't you start by posting a ffprobe of the file? The container is AVI but we doesn't know anything about the codec.

ffprobe file.avi

FFprobe is a tool found in the FFmpeg package: https://www.ffmpeg.org/download.html


why exposing with 18% gray card does not give IRE near 40 I am trying to understand how to get perfect exposure using gray card.
With my Sony a6500 using ITU709 gamma, I locked exposure by doing spot metering on the gray card.
When importing in final cut pro the waveform monitor show IRE value near 25 for the gray card.
Shouldn't it show between 40 and 43 for 18% reflectance mid gray?

I was stupid and using spot focusing and not spot metering.
So the metering was wrong even if the focus was right in the middle of the card.

I repeated the test and it now give me 40 IRE as expected.


Sigma 18-35mm, f/1.8 DC HSM ART Image Circle / BMPCC4k with 0.71x I am currently figuring out which lens I should get. I found the Sigma 18-35mm, f/1.8 DC HSM ART which looks quite interesting as I want to have a nice bokeh and shallow DOF.
But it is for APS-C only.

I will use the Metabones Speedbooster 0.71x on my BMPCC4k, so the crop factor is 1.349, so slightly bigger than 1.5 of APS-C. Is the image circle of the Sigma big enough to support 1.349 crop without much vignette?

I found this image on https://www.the-digital-picture.com/Comparisons/Sigma-18-35mm-f-1.8-DC-HSM-Lens.aspx and if I have done it right, the red circle is my "MFT" and the golden one is APS-C. Could anyone check if it's done right?

Also, does anybody know if it has a direct focus or a servo focus?

Thanks!

Your calculations are right.

But if you take a look here: https://www.fredmiranda.com/forum/topic/1279757/0
The vignette is much stronger. With the images provided by Aloicious I get a vignette.


How can I sync two audio sources running at different speeds I know Vegas is more of a video editor, but I like the visuality and ease of syncing audio.  I've done this easily with 2 digital sources, it's a snap.
The problem lies when you try to sync old analog sources that were recorded on different equipment and different battery strengths.
I've got two sources.  On one source, the required clip runs exactly 2,481 seconds long (from 4:16:24 to 45:37:00 on my timeline).  The source I want to mix it with runs exactly 2,422 seconds long (from 4:16:24 to 44:38:00 on my timeline).  I calculated this by syncing exactly the start point and lining the 2 tracks up, and then determining the exact same end point on both tracks.
How can I sync these so they both run the same length of time, and match up along the way?
I'm using Sony Vegas Pro 13.

Well, I sorta figured it out so I'll put it as an answer, although I hope someone comes up with a better suggestion.
I had to eventually cut one track into (approximately) 5 minute segments.  I placed my cursor at the end of each segment, held the shift key and did a click-and-drag with my mouse to perform a "time shift" until the tracks aligned.  Then, I moved the next clip up against the first and repeated the process.  I found if I did this with the entire track, it still went out of sync, so by chopping the track into (approximately) 5 minute intervals it kept it closer to sync.  That might be due to the speed of the source tape varying as the batteries got weaker.  I tried to cut the track near a large volume peak or valley to make it visually easier to align the tracks.
All in all, it was still much easier than trying to do this with something like Audacity or Sound Forge.


Is converting DVD to a format to play on a tablet legal (in the UK) Simple question, is it legal to take a DVD you already own and convert (rip) it into a format (such as .mp4) so it can be played on a tablet or laptop ?

In the past you had to use various nefarious means to convert CD to .mp3 but now, iTunes & windows media player come with the functionality built in (which in my mind legitimises the practice).

So, assuming DVD -> .mp4 is legal, is there any legitimate software to make the task easy ?

Please note this is UK legislation
After some research I found the following in a Government consultation paper:
From MODERNISING COPYRIGHT: A modern, robust and flexible framework
http://www.ipo.gov.uk/response-2011-copyright-final.pdf

There is a clear mismatch between what is permitted by law and the type of private copying that most people think is reasonable. The current law imposes unreasonable restrictions on consumers and may restrict the range of products and services available to them by limiting opportunities for technological innovation. In response to this, the Government will introduce a narrow technology-neutral private copying exception which applies equally to all types of private storage and all types of copyright works. It will allow a lawful owner or buyer of a copy of a work to reproduce that copy for their personal use, but would not permit them to share copies with other people.
This exception would therefore permit someone to copy music from a CD they have bought onto their mobile phone, or to back up an eBook onto their computer hard disk or other private storage, whether held locally or remotely. It would be allowed regardless of contract terms to the contrary. However, it would not allow someone to give copies they have made to friends, family or the wider public, nor would it permit copying of rented, borrowed or streamed content.

And

A permitted act that only allows copies to be made by and for a person who lawfully owns[41] an original copy will remove restrictions on the use of copyright materials that most people consider to be unreasonable and unnecessary, while drawing a clear line between acceptable personal copying and unacceptable sharing of copies. Consumers appear to recognise that sharing copies can harm creators and the Government does not want to dilute this message. Rights holders will therefore still be able to offer family copying and other licences that add value over pure private copying by individuals. They will also remain able to use technological protection measures (TPM) to restrict copying of works as and when they wish to do so.

[41] - This would include downloaded digital content that has been purchased to keep (or licensed in an analogous way) such as eBooks or film downloads, but not rented or streamed materials.
So, as I read it, you can make copies of CDs, eBooks, DVDs/BluRay if and only of they have no TPM on them.

CDs don't have TPM so copying (format shifting) is legal.
eBooks have TPM so copying is illegal.
DVDs/BluRay have TPM so copying is illegal.

But, it's the act of 'breaking' the TPM which is illegal. not the actual copying as long as the copy is for another device (format shifting) or for an archive/backup copy (whether on a local hard disc or a remote storage facility (the cloud)).
So, clear as mud really !


After Effects CS6 Problem I try to render with After Effects CS6. I have a weird problem. Here render result:

Sometimes, it's show some old frames as you see in video.

Here normal video (rendered with Camtasia):

My AE render settings are default. And this is being every (fresh&new) project. Would you have a suggestion for this problem?

Thanks a lot.

The issue was with Camtasia 8's capture. Converting from the AVI format to a MOV format fixed the issue.


Convert Horizontal 1920x1080 mp4 video to Vertical 1080x1920 mp4 with Actual content size of 1080x608 How to convert horizontal 1920x1080 mp4 video to vertical 1080x1920 mp4 with actual content size of 1080x608
I know ffmpeg can do it, but don't know how to do it.

FFmpeg does it through the video filter - transpose; clockwise or counter-clockwise option is available.


Where can I get Rapid? I was watching this video by CorridorDigital and I heard them mention Rapid. I can't find it on Google. Could someone link me to it.

It appears to be RapidForm which has now been bought out (or changed name possibly) to 3D Systems Geomagic.  The website is here.  I found this by looking for mesh refinement software matching the term Rapid and that seemed likely the best match.  In particular, it appears to be GeoMagic XOS.  I don't personally have any experience with the particular software.

Basically the point behind the software is to make refined meshes from a point cloud.  3D scanners like the Kinect don't actually form a mathematical model, instead, they generated large numbers of points at a given distance from the sensor.  These points are formed into a cloud which then has to be modeled into a vector based solid mesh for rendering purposes.

This process is actually incredibly similar to converting a bitmap image into a vector graphic, but it has to be done to produce smooth, solid surfaces in 3d, so it's a bit of a complex and specialized operation.  Software like this allows for the best fit mesh to be found and to ensure that it makes a solid, detailed mesh that doesn't have holes in it that could cause problems with the geometry.


If I screen-capture a snapshot from a HDR movie, will the snapshot image be a HDR image? I have a HDR movie content playing on a HDR supported PC, using software like the VLC layer. If I take a snapshot to get a png image file, will the image file include the HDR information? That is, if I compare the image file with the movie frame where it is snapshot side by side, will they look exactly the same?

If I take a snapshot to get a PNG image file, will the image file include the HDR information?

How do you take a snapshot? 10 bits minimum color depth of the PNG has the same effect on your HDR display.


How do I add an intro to a video without having to render the entire video again? I have some 5 minute footage that I have, I simply want to add my intro and outro to that video before putting it on YouTube, if I do that within after effects, I have to render all of that which would take forever on my computer, is there an easier option?

Using After Effects, I don't think there is.  But there are ways to make your life easier.
If you have a complex comp, if you've rendered the whole thing out to a format like ProRes (even though the files are large), it's relatively quick to drop in an extra intro and outro either side of your ProRes file, so you won't have to re-render the entire project again. You could also look at pre-renders to speed up your projects.


Automate video production with After Effects CC I am tasked to produce ~100 videos of 10 minutes in After Effects. The videos will later be commented by voice, and I am tasked only to make the "motion" part.

Each video use:

about 30 "image" scenes (5s): an image is being slowly zoomed in
about 50 "footage" scenes (10s): a footage is being shown for 10s
A few other misc. animations (intro and conclusion with logo)

In each new video, I need to change:

The 30 images
The 50 footages (I will be given links from Youtube along with the timestamp like "0:16 to 0:26")
A limited amount of text, here and there

I plan to make the template first, and I was wondering if you guys knew a smart way to program each video (ie auto-replace the 30 images, the 50 footages and the predefined text, then build and go on to the next), a bit like "mass-mailing" for instance.

They say in programming, "if you have to do it more than 3 times, program it"... I think 100 applies! However, being unfamiliar with After Effects, I do not know where to begin! Guidance will be much appreciated.

You could achieve a certain automation by creating precomps for each clip. Then, drag every alternative file into each precomp and just stack them on top of each other. Now, apply the motion effect (the zooms etc.) to the precomps instead of the footage directly. That way, you can just hide the top layer to that the next image is visible, on which the animation will automatically be applied since it sits in the same precomp you animated before. Alternatively, to make the process even easier, you could script an expression that looks at the index of each layer in your precomp and hides every first layer for every comp, or every first and second, etc. etc. When it comes to the scripting of it though I must admit that this would require a few hours of thinking on my own, so maybe someone smarter can help you with that :D


Can video have multiple streams (like it has 2 audio streams) Is that possible, that a video (.mp4 or etc) had two video streams and we could to do work with each stream individually ? (like we do with 2 audio streams and we can remove any of them)..

if so:

1)  do you know which video editors can handle such videos? Adobe Premiere , Sony Vegas, DaVinci or ... ?

2) At this moment, my typical MP4 files are converted by youtube (after upload) to i.e. mpeg-4 10 AVC. And will those 2-stream videos will be converted to 1-stream video anyway? (maybe I have to ask that to YT forum, right?)

Yes. MPEG-4 Part 14 (the MP4 container format) supports any number of objects (e.g. video, audio and subtitle streams) and isn't limited to only one stream per content type.

In practice however, you seldom see a video file that has multiple video streams, because the range of applications for this is very limited. I would also advise you not to put multiple video streams into one file, as (a) users don't expect it, many won't know how to switch the video track or not notice there is a second video track at all and (b) many players (soft- and hardware) aren't equipped to play files with multiple video streams and either won't have any option to switch between streams or fail to play the file completely.

It is also more common to use Matroska (.mkv) containers for video files with multiple audio/subtitle streams, but even with those, you rarely see files with more than one video stream.


What to do with a VMP video file I recieved a VMP video file to convert to avi or mpeg or something. I searched the web but I cannot find any association with this file.

Can anyone help? Which program does this file come from?
What can I do with it?

This is likely a video from a Sony/Vaio product having a vmp extension.  I don't know of any third party converters, however you should be able to export the video file from your Vaio/Sony product itself.  It'll automatically create an mpeg video file for you.


Blackmagic RAW get Thumbnail in Windows Explorer Is there any known Plug In or similair which can show BRAW Thumbnails in Windows Explorer? Or does anyone know how one could write such an Plug In?

I've created a thumbnail provider available from here https://github.com/tom-gangemi/braw-thumbnail-provider/releases/tag/v1.0.

All you need to do is extract to your desired install location and run register.cmd.


Save export settings in Media Encoder I have an hour+ project in Premiere Pro that is a live performance of a musical group.  I've broken it up via Markers into 15 songs.  I then, mostly with a lot of "by hand", exported the 15 songs to Media Encoder and it produced 15 videos.  The catch is, the project is "mostly" done but I will likely want to go back and tweak things here and there.

Is there a way to save the 15 export settings as a single unit?  They are all exactly the same except for the in and out points and the output file name.  Or... perhaps there is some type of automation that I can use with Media Encoder so I can have an external "script" that would fire up the exports.

If I right click on one of the jobs in the queue (that has completed), "Export Settings" is disabled.  Perhaps that is what I'm looking for?

Really, utopia would be if I could select a marker and say "Export" and it would pick up the title from the marker as well as the in and out points (i.e. the work area).

No there isn't.

You could nest each section from your master timeline into it's own timeline, from the in and out points of where your start marker to your next would be.

That is the only thing I could think of. You could still work off the master timeline provided you dont do any time shifts / move any content up or down the timeline.

Then you could batch out the sequences to AME and apply the pre-set to all of them at once for export.


Low action Kickstarter video with Nikon DSLR: do I need an external lens? I'm a complete video novice, who's only ever shot anything with his parent's handicam. I want to make a video for a Kickstarter project, and I want to do a good job.

The video will be very simple, with the camera completely still and only a couple of shots, likely all of them indoors.

I've been looking into renting a video capable Nikon DSLR for a couple of days, and I'm wondering, do I even need an externally attached lens? Will the camera be fine without one? What are the consequences of not using one?

If I do need a lens, what should I look for?

I just finished working with a company that has had several very successful Kickstarters.

IMHO, lighting and audio are more important than camera type for this type of video, as long as you have a pro-sumer camera that shoots decent 1080p HD.  Many successful campaigns have been shot on a DSLR with a stock lens.  If you want to buy an additional lens then your first lens should be a "nifty-fifty".

An external microphone is way more important than camera.

Here is the one piece of advice that was given to me by someone that has run mutltiple multi-million dollar Kickstarters.  Don't let someone that is dry and boring be the spokesperson for the video.

Of course the owner/CEO of the video wants to be in the video, but that's not always the best choice to be the talking head.  Instead use them in action scenes, Like at a workbench or a design table.

EDIT:
I re-read your post.  I assumed it came with a kit lens and you were wanting to know if you should upgrade the lens.  The poster above is correct, you have to have a lens. But what I don't understand is why are you going with such a high-end DSLR?

The camera you are looking at, the Nikon D7200D, is a great camera.  But it's also an overkill for what you need.  It's a 24MP camera that can shoot video at 60FPS.  HD video is only 1.8 MegaPixels and you only need 30FPS. For almost the same price as the rental of the body and lens you could buy an older model (refurbished or used) DSLR with a 50mm lens and own it.  This would give you time to learn how the lens AND the camera work since they are two different beasts.

Also because a DSLR is not primarily a video camera, it's actually a little bit more complex to setup for video.  Not ideal for a beginner.  A Pro-sumer HD video camera would be a better choice but it costs more.

So I would actually recommended, for a beginner, a camera with a built in lens.  Something like a Nikon Coolpix that shoots full 1080p.  You can definitely get one of those (factory refurbished) for less than what you would pay to rent the Nikon D7200D with a lens.

I know I'll probably get criticized for that recommendation.  But if you don't know how to use the D7200D, then you probably won't shoot anything better than would with a Coolpix.

Now all you need to do is learn 3 point lighting.  If you put a key-light on the back of your subjects head, then you will shoot something better than most other kickstarters.


Nested Sequence that plays fine alone shows up as entirely black in Master Sequence I'm running Adobe Premiere Pro on a Mac, and after benching a project for a while and now coming back to it, some of the nested sequences will play just fine in their timeline, but show up as audio with video blacked out in the master sequence timeline.

Here is what the nested sequence looks like playing from its own timeline:

Now here is what it looks like when used in the master sequence:

Notice how it appears as all black both in the source monitor and in the program monitor.

What is this and how do I fix it?

Have you tried clearing all rendered caches? That would be my first guess.


resend headers NUT formats If I do this
ffmpeg -f dshow -video_size 720x480 -framerate 29.97 -i video="Roxio Video Capture USB":audio="Line (Roxio Video Capture USB)" -c:v mjpeg -c:a pcm_s16le -map 0:v -map 0:a -f fifo -fifo_format nut -drop_pkts_on_overflow 1 tcp://localhost:6600

I can connect to TCP from a player only once.  The NUT headers are in the FIFO and part of the video stream is dropped so I stay close to real-time, but if I disconnect I've lost the nut headers and no player will reconnect even though the TCP port is still sending data.  Is there any way, BESIDES USING MPEG Transport Stream, to resend the headers?

Although probably not best practice, this seems to do the trick:

Take a NUT file, same codec and dimensions;
ffmpeg -i nutfile1.nut -frames 2 -c:a copy -c:v copy -f nut nutheader.nut

And then a little piping hijinks:

nc 192.168.1.161 6600 | cat nutheader.nut - | ffmpeg -i pipe:0 -c:a copy -c:v copy -map 0:a -map 0:v -f fifo -fifo-format nut -drop_pkts_on_overflow 1 pipe:1 | nc -L -p 6601

You get a 'discontinuous DTS' when you connect the first time and headers are duplicated, but whatever.

And you get one 'packet damaged' when you start the standard input after the headers, but it immediately and with extremely low latency resynchronizes.


Good software for a simple, slide-show style video presentation? So we have to make a short video (Less than 5 minutes) for a leadership course as part of our degree. (Engineering)

We're not really video people, so we've decided to simple slide show style video (Using something like Prezi, so that it at least looks and feels somewhat proffesional) with some voice-overs (which we've already recorded.)

Can anyone offer any suggestions for a simple piece of video edition software that's free? I don't need anything too feature rich, just something that can let you mix visual with audio and is quick to learn?

(Also, as a quick aside, can someone suggest background music that's generic and vaguely inspiring?)

Edit:
Posted my own answer, but still chose Vladislav's answer because it was good. Also, Youtube Audio Library was awesome. Best background music ever. Thanks.

So, I ended up using Prezi to run a presentation and camtasia studio to record it and render it to the video file I needed. Both were 30 day free trials, so that worked out nicely.

I put all the audio in Prezi (It lets you add background music for the whole presentation as well as voice overs on a slide-by-slide basis) but I could have just easily have done it in camtasia.

I needed the voice overs for timing in the Prezi, which is why I did it that way, but there's nothing stopping you from just putting them in anyway, and removing the sound when it gets to camtasia, and putting them in as separate tracks. You'd probably have better control of volume, etc, that way.


Loop the first frame of a video and then play a selected portion of the video I would like to to play the first frame of an input video for 260 frames and then play frames 310–930 of the input video:

$ ffmpeg -i video.mp4 -i video.mp4 -filter_complex '
    [0:v]loop=loop=259:size=1:start=0[first-frame];
    [1:v]trim=start_frame=310:end_frame=930,setpts=PTS-STARTPTS[rest];
    [first-frame][rest]concat=n=2:v=1:a=0[output]
' -map [output] -c:v libx264 -crf 18 -y output.mp4

The above command produces the first frame of the input video for 260 frames as expected, but then continues with frames 0-620 of the input video followed by frames 310–930 of the input video.

When I drop the [first-frame] part, frames 310–930 of the input video are correctly produced:

$ ffmpeg -i video.mp4 -i video.mp4 -filter_complex '
    [1:v]trim=start_frame=310:end_frame=930,setpts=PTS-STARTPTS[rest];
    [rest]concat=n=1:v=1:a=0[output]
' -map [output] -c:v libx264 -crf 18 -y output.mp4

This is perhaps a timestamp problem, since the documentation for the concat filter clarifies that “for this filter to work correctly, all segments must start at timestamp 0.”

I am using the following version of ffmpeg:

$ ffmpeg -version
ffmpeg version 3.2.12-1~deb9u1 Copyright (c) 2000-2018 the FFmpeg developers
built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
configuration: --prefix=/usr --extra-version='1~deb9u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libebur128 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
libavutil      55. 34.101 / 55. 34.101
libavcodec     57. 64.101 / 57. 64.101
libavformat    57. 56.101 / 57. 56.101
libavdevice    57.  1.100 / 57.  1.100
libavfilter     6. 65.100 /  6. 65.100
libavresample   3.  1.  0 /  3.  1.  0
libswscale      4.  2.100 /  4.  2.100
libswresample   2.  3.100 /  2.  3.100
libpostproc    54.  1.100 / 54.  1.100

A shorter method is

ffmpeg -i video.mp4 -vf 'select=eq(n,0)+between(n,310,930),setpts=if(eq(N,0),0,(N+260)/FRAME_RATE/TB)' -map [output] -vsync cfr -c:v libx264 -crf 18 -y output.mp4


How to distribute multiple clips on the timeline, by Date and the time of the first one? I have an existing project in Adobe Premiere 2017 and I would like to import multiple clips in it.

I already have the primary camera in sync with the Audio, and I would like to bring the secondary camera consisting of multiple clips which are not continous (there are time gaps between them).

By knowing that the video 123.MOV created at 1:39 PM should be at minute 7:55 on my timeline, and after making sure it is in sync with the audio, I want the other ones to be set in sync as well, adding the timestamps between the Created Date on the timeline.

I am not sure if Timecode helps here, but I am wondering if there is a way to import them in the project with the time gaps between them and then I will be able to select them all and sync them at once.

How can I do that?

In Davinci Resolve, I would solve this problem by creating a multicam clip using Timecode as the method for synchronization and keeping clips organized by camera.  This will create a multicam clip with only a single camera, but each clip spaced out according to its timecode.  If you like, the multicam clip can then be decomposed in place and converted into a compound clip, preserving the spacing between the video clips.  You can then place the single compound clip to start at 7:55 and all the rest of the clips inside the compound clip (or multicam clip if you didn't convert to compound clip) should line up as expected.


Photoshop CC video render has no sound On Photoshop CC 2015.0.0 I can play my video and hear the camera audio soundtrack. When I render the resultant MP4 has no sound. My movie consists of Nikon .MOV files, and some text overlays and is 35 minutes long. Render settings are shown below.

What am I missing?

[Edit] Preset options shown below.

The "Adobe Media Encoder" drop-down also contains Photoshop Image Sequence (which will save a series of JPEGs).

Adobe released Photoshop CC 2015.0.1 this evening and it seems to have fixed the problem. (I had tried again with a short clip and couldn't get any sound.)

So, unfortunately, I don't really know what the problem was, but this patch seems to have fixed it.


What is/are the best free tool/tools for editing my videos? I need to complete 4 specific tasks on my videos.

Stabilize.
Crop to Anamorphic
Convert resolution up or down to 720p
Convert to mp4 (H.264)

Can someone point my in the right direction to the best free tools to complete these tasks?  I'm using Handbrake to do all my -> mp4 conversion.  I've tried VDUB with DeShaker and Mercelli (not free) for stabilization.  Mercelli only lets me output to wmv or mpg but it compresses and creates a lot of pixelation in the process.  Not to mention it crashes more then Windows 95.  DeShaker is ok, but if the person taking the video moves around at all, it distorts and bends a lot in the background.  I can crop to anamorphic from Handbrake but it doesn't let me scale the videos up to 1280x720.  Is there a good free tool that will do all of these?

Any help would be appreciated.

Thanks
-Craig

You can download a FREE 30 trail version of Vegas Pro 11 from Sony.

http://www.sonycreativesoftware.com/download/trials/vegaspro

I've have Vegas Pro 10 and I have used these features: Stabilize, Convert resolution down to 720p, and convert (render) to MP4.

I never convert resolution up, it just looks terrible (see my comments above).

By "Crop to Anamorphic", I am assuming you mean to convert 4:3 to 16:9, I have not tried this with Vegas as all my originals are already 16:9 HD. So you might want to google for that part.

If you go this route search YouTube for tutorials on each item as it will speed up your learning curve considerably.

Caution: if you want to take a 4:3 SD video and make it into a 720p 16:9 HD it's just gonna look terrible. Why? Because you are asking the software to expand the resolution, this never looks good. It's ok to reduce resolution say go from 1920 X 1080 and step it down to 720p, that's just fine, but when you try to go the other way you are asking the software to essentially make up material that is not there.


Marker animation trigger from parent composition Is it possible to trigger animation from parent comp layer? I have been trying this expression with my basic coding skills but couldn't make it work.

n = comp("myparentComp").layer("myLayer").marker.key(time);
if(time < marker.key(n).time){ n=n-1;
}
if(n==0){ n=1
}
t=time-marker.key(n).time;
thisProperty.valueAtTime(t)

Totally possible, but there are some problems with your expression.

n = comp("myparentComp").layer("myLayer").marker.key(time);

In this line n is going to return a marker key object. However the last part of the line uses the current time in the method marker.key(time). This won't work. The marker.key() function expects an int referring to the number of the marker (1-indexed, so the first marker is marker.key(1), because WTF adobe). A marker key has a time property, which is probably where you're getting confused. Also then you're treating n as if it's an integer, and you use a variable marker without declaring it or giving it a value.

If you want the animation to trigger on the first marker, it should look like this:

var marker1time = comp("myparentComp").layer("myLayer").marker.key(1).time;
if(time < marker1time){
  t = 0; //hold the animation until the first marker
} else {
    t=time-marker1time; //will start at 0 at the point where time == marker1time
}
thisProperty.valueAtTime(t);

Some basic JS tutorials would probably help. I recommend the w3Schools ones, they're web-design focused, but almost all JS tutes are.


what are the elements of a lavaliere mic system? I'd like to buy 4 lavaliere mics for my video recording, and I need some education about lav setups.

I imagine that wireless mics would be easier to manage, but they probably cost more. I imagine I would need the wireless mics, and a receiver for each.  I'd also need a 4-track digital recorder. Or does each lav mic include a digital recorder? Finally, I'd need a way to transfer the audio files to my computer as either MP3 or WAV files. (Synching them with video should be simple; I'll use a clapperboard.)

Most wireless lavalier microphones for video recording use are sold as single receiver + transmitter packages. I believe you can get receivers that take more than one input, but they are designed for AV production use (e.g. stage shows and so on) and are mains-powered and expensive. So if you want wireless you'll probably have to buy four transmitter + receiver sets. Wired microphones are certainly cheaper, but lapel mics and cables are problematic if your subjects want to move around. If they're not moving around, then maybe you don't need lapel mics.

Edit Someone has recently sent me a link to these Sony Bluetooth microphones, which look like a great low-budget option. You'd use them just like normal wireless transmitter / receiver units.

Audio recorders usually come with built-in microphones, but microphones don't usually come with recorders, if that makes sense. Given that digital recorders are fairly cheap these days it is tempting to use four recorders worn by each of the subjects with a wired Lavallier microphone, rather than four wireless sets, but the downside to that is that you can't set levels or monitor the input, so if there are problems you won't know until you get to the edit suite. And given that lapel mics are prone to such things as clothing noise or the subject accidentally hitting them you could end up with problems.

As far as your recorder goes, you could either get a four track recorder, such as a zoom H6, or a mixer to mix the four tracks into a stereo signal which then gets sent to a stereo recorder. Recording four discrete channels gives you the advantage of being able to re-mix the audio at a later date, and to edit around overlapping dialogue, but obviously it's going to cost more.

From the recorder transferring to the computer is trivial, most record onto CF cards or such like, and the recordings can be transferred via a card reader or often via USB. Synching is also easy, even without the clapper board: editing software such as Final Cut Pro X and Adobe Premiere can synch audio tracks automatically.


Add image under the video with ffmepg I want to extend basic usage of watermark and put it under the video.
That means. I have input video 720x480 and image 720x20.
On output i want to have video 720x500 where video aspect is preserved and positioned to top and image is added to bottom.

input video

|--------------------------|
|                          |
|                          |
|                          |
|          720*480         |
|                          |
|                          |
|                          |
|--------------------------|

input image

|--------------------------|
|          720x20          |
|--------------------------|

output video

|--------------------------|
|                          |
|                          |
|                          |
|          720*480         |
|                          |
|                          |
|                          |
|--------------------------|
|          720x20          |
|--------------------------|

Thanks

Use the vstack filter:

ffmpeg -i video.mp4 -i image.png -filter_complex vstack output.mp4

If the image is not the same width as the video then resize it with the scale filter:

ffmpeg -i video.mp4 -i image.png -filter_complex "[1:v]scale=320:-1[bottom];[0:v][bottom]vstack" output.mp4


How can I transcode a PAL-formatted videotape in the United States? A friend has come into possession of a VHS tape whose video is encoded in the PAL standard. He would like to play this tape back and record the output into some format that he can easily play back in the United States - either NTSC video, or some digital format. He can't just play it in a common local NTSC VCR, as he hears sped-up sound and sees no video.

What equipment would be required to do this, and are there any other considerations that need to be taken into account, such as power adapters?

You need two things - a PAL VCR and a digital video converter than can speak PAL. The last one I bought (in 2005) was software configurable for (or could autodetect) PAL and NTSC, and several that show up on Amazon appear to be both PAL and NTSC compatible. It looks like VCRs that are PAL compatible are available on both Amazon and EBay.

When acquiring a VCR, pay attention to its power supply requirements. I haven't purchased a VCR in over a decade, so I have no general advice on what to expect. However, if the VCR expects 220-240 V and/or 50 Hz, then you will need an inverter in order to use it in North America (120V @ 60Hz).

Edit: Once you've digitally captured the video, you should be able to play it on a PC or most mobile devices. If you really need to transcode it to NTSC, then something like VLC or Apple's Compressor should do the trick.


VLC Alternative for fine review media with possibly frames control and detailed codec informations Some people around the web say that VLC is the cinderella of the video players, they say it make too much automatically picked video filters and conversions that not decode properly the media in the best way.

While I'm not sure about what this persons are talking about the reason why I use VLC is without doubt the capability of being able to play audio/video with almost every codec and in whatever container without extra setup even by running just VLC in portable mode from a folder.

The same folks suggests XMBC but I don't need a full screen remote style video player, what I would like instead is a program capable of:

play practically everything without codec installation
fine playback controls to move across frames and keyframes ( a nice interface )
fast and handy codec informations to read in "one sight" Container, Streams, their Codecs and Bitrate used, then all the other useful info
if there are uncertain condition like a color conversion or something like that have a menu that allows you to try various options without force the user to have a certain choice.
free but highly appreciated OPEN SOURCE and MULTIPLATFORM
well optimized
No fancy Skins, possibly no skin support at all, this is to be intended as pro users program we like the os standard windows.

Bonus:

metadata full edit and managing
video proofing with gamut warnings and settings like photoshop for display in rec 709 or other color spaces
if the video is in a RAW supported format es: RED, CinemaDNG, ArriRAW would be nice have some minor extra controls to shift the exposure during the play and check also for clipped areas with red (highlights) and blue (blacks)

In short a VLC with Steroids for media review, able to show you all the flaws and things to check after you exported a video from your common tools/apps.

Would be cool if a program like this would exists :)

PS: Vlc has a codec info windows, but it could be improved, also the bitrate is not calculated in the same better way of ffprobe. Also vlc have not a nice and handy frame browsing interface, it also doesn't allow stuff like scrubbing on the timebar holding shift like you do in VirtualDub and so on. I'm searching for a program that offer the best sides of all this softwares.

I haven't used VLC as my primary player since 2007. I switched over initially to KMPlayer and then Potplayer. Potplayer allows fairly flexible splitter and codec assignment for decoding. It also sports a whole host of video and audio processing filters. In fact, I believe that one can use Avisynth filters to process the video during playback, too.


Can I clean up Premiere Pro CS6 preview files like this? I did a test with a small Premiere Pro CS6 project and discovered that for each change I made to an effect Premiere generated a completely new preview file and stored that alongside the old file ( which was apparently trash at this point )

Eg I did a rotation change and rendered a section and it created a preview file. I repeated this process and it made a second file. I would have expected it to overwrite the original because when I deleted all the preview files and generated a new preview it only ended up with a single preview file ( seemingly the same file as the last created ) — so I'm concluding that it would never use the previous 4 files yet it didn't delete them or give me an option to.

The reason I did this is that the preview files folder in my main project is 15GB in size; and I'm assuming much of this is trash based on the above. So I moved it out of the project folder pending deletion and generated a new set of preview files for the project, which which came out around 8Gb - and it seems to work fine.

My questions is:

Is there any problem with this method of regaining space other than it takes time to regenerated the preview. I mainly am curious because I haven't seen a reference to this technique anywhere; and also because I wonder why Adobe didn't add a button to purge and regenerate preview files (at least that I've seen) since it's fairly straightforward and reclaims back so much space.

You can delete Render files by going:
Sequence > Delete Render Files

Or by using third-party programs.


Generating numbers counting up with fix poisition for units In After Effects, I am trying to programmatically generate numbers that count up. But when the numbers start counting up, it is pushing the units to the right.

How I can make units position fixed (right aligned)?

Here is the code I'm using:

startT = 0;
endT = 8;
beginVal = 143;
endVal = 50143;
t =Math.round(linear(time,startT,endT,beginVal,endVal));
t += "";
t.replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1 ");

Not sure if this is what you mean, but can't you just set your text object to Align right in the Paragraph tab?  So all the text is right aligned.  That way the units won't jump around.


Lossless HDCP stripper? Is there a product that allows you to strip HDCP from HDMI and that does not loose quality?

Yes. The companies Spatz-Tech, HDFury and Faroudja have products with that functionality in their portfolio. But there are selling restrictions in many countries.


AE - is there a way to import images via list and add random position to them? I use After Effects CS6,

I need to add a lot of pictures inside my comp,

they need to have random position
(if I could set the "range of the randomness" that would be great)

is there any way to do that ?

and I'm not looking at a wall image plugin (with these plugins, all pic are in the same plane, but I need randomness on the Z-axis too)

I'm trying to make something similar to the TV Show Person of Interest: how the AI has multiple image when "we" are inside "his mind". link to img

I have already done a big part of it manually, but it just takes too long to do it with new packs of images.

Thanks.

Dump all your images into your timeline. Select one and alt-click the stopwatch on the position property, to add an expression. You need to write a javascript expression that returns an array of 3 numbers that will randomly position the image within the comp. This will do it:

seedRandom(index, timeless = true);
var x = random(thisComp.width);
var y = random(thisComp.height);
var z = random(thisComp.width);
[x, y, z]

IF you right-click the position property and choose copy expression only, you can then paste it to all the other images in your comp and they will scatter to randomly fill a cube the size of your comp (and as deep on the z axis as the width of your comp).

How it works

(read this if you want to be able to hack it to your own needs)

The seedrandom function sets the random seed for the random number generator, and we give it two parameters, index meaning the layer number, and timeless=true. By using the layers' index to generate the random number, each layer will have a different set of coordinates. Timeless=true means that the random number doesn't change over time.

var x = Math.random(thisComp.width) sets the variable x to have a random value somewhere between 0 and the width of the comp. If you wanted this to be a different value you could type in a number instead of thisComp.width. All three variables are set the same way.

The last line puts them into an array, which is what the position property needs.

To refine it you might want to use the guassRandom function instead of random - that will mean the images will cluster towards the centre, like a galaxy. You could also create a null and add three slider effects to it (in effects>expression controls). You could use them to control the width, height and depth of the cloud. To do that select the bit inside the random function that says thisComp.width, delete it and with the cursor inside the brackets grab the pick-whip (the little spiral near the expression twirl down) and drag it to the slider effect control.

The result should be that the line will now look like:

var x = gaussRandom(thisComp.layer("Null 1").effect("Slider Control")("Slider"));

Do that for all three dimensions using a different slider for each and once again copy the expression to all the layers. Now you can control how far they spread with the sliders, and even animate it, by animating your sliders, so for example they could all spread out from the centre over time.


Devices for slow-motion video recording I'm interested in shooting slow-motion videos of sports (eg. ping-pong, badminton; for analysis and such). After trying an iPhone camera I wish to get something higher quality/more crisp (ideally 1080p@240fps).
However, finding something decent at an affordable price-tag seems to be rather difficult. hispeedcams.com is a quite good source for this purpose. Here are some notable finds.
research
rather professional solutions (too expensive)

RED RAVEN "[...] 4.5K Full Format (FF) at up to 120 fps, or in 2K FF at 240 fps, [...]" (at $8,950.00 (USD), €9,030.00 (EUR), £7,970.00 (GBP))
Panasonic AG-DVX200 "120-fps Variable Frame Rate" ($3,795.00)
SONY NEX FS700 "120fps at 4K" ($3,499.00)

dedicated high speed cameras (more than needed)

edgertronic SC1 "- 701 fps @ 720p: Color 8GB DDR3 Install IR Filter - 400-675nm response" ($5,495.00)
chronos 1.4 "1,057fps [at] 1280x1024" (2,999.00$

action-cams (too limited): ("240fps at 720p and 120fps at [...] 1080p")

Sony FDR-X3000 ($348.00)
GoPro Hero 5 Black ($399.00)
Yi 4k+ ($339.98)

DSLM/MILC (which would also be nice as default photo cameras but don't have a optical TTL view finder)

Panasonic GH5 apparently 1080p@180fps (€ 1.999,00)
Sony A6500 1080p@120fps ($1,399.99)

It would be nice to have something more versatile than action-cams, but less expensive than those professional devices. As I don't want to shoot slow-motion only, cameras specially designed for that aren't really what I am looking for either.
This leads to the (still quite expensive) GH5 (or similar DSLM) and also to a few
questions:

What should I look for in gear for a beginner?
Is there something (DSLRs/DSLMs) in between (regarding price) GH5 and action-cams (similar to a6500) supporting slowmo ?

Some specifications mention that high-speed capture is only available for a few seconds

Is there always a maximum on how long can I capture slowmo if it is not noted?
If a camera is advertised with (eg.) 8sec 1000fps, at which rate could it record permanently then ?

note:
I have asked for DSLRs on photography already with comments mentioning the GH5 only - I can remove this partial question if it is not fitting
I have split off the SDI part-question here.

You may want to look into Sony's camcorder line (even legacy; like the NX5U).

The NX5U and I think even the FX1000 (which is an HDV Tape Format and can be had used on a place like ebay for under $1000) could do bursts of full 1080p 240+ for a "limited time".

If I remember correctly the FX1000 by sony could do 240 frames at for 10 seconds. It would buffer the video into internal memory; then queue the tape; then record to tape when the 10 seconds was up.

It was limited in terms of it's usefulness; but it sounds like based of what you want to use the slow motion capture for; it may be worth looking into to.

Burst cameras (even the iPhone now does this); will give you a higher frame rate, with limited record time for a much lower price than say going the RED route or Phantom Route.

Or you could rent a RED, RED Epic's will do 480FPS at 1K; and they can be rented cheap; as they are everywhere... and sit on the shelf most day's of the week by people who own them.


Frequency of refreshing for a green wall We are setting up a big cellar as a studio in which we will shoot with a green screen.
At this point we have two solutions:

Put in place a curtain which will be attached to a rail on the ceiling.
Paint directly the wall in green ( with the proper paint of course )

What do you think is the most practical?

Is there a risk to have chroma-key issues with the curtain?
If we opt for the paint, how often should we expect to have to refresh the paint?

Thank you for your help!

Practical or most effective?

Green Screen work demands the following optimazation points to have it be effective.

flat even lighting, no hot spots, no dark spots.
no shadows,
no reflections,
the lighting has to be bight enough to register the green correctly, aka no noise.

Additionally, to help avoid hot spots, plan on a fresh drywall/plasterboard for that wall and when fixing, ensure sunk and smooth plastered nails. This will help you get a consistent surface for the green.

A curtain if it can be expanded to be absolutely flat with out any wrinkles might work,
but I think this will be very troublesome.

Painting the wall with the appropriate paint would be more effective.

When to repaint?

Establish a base-line video test, that is repeatable, same lights, same object(s), same camera. Run this in your post production chroma-key video track before each production use, and it should be obvious if the paint needs to be refreshed.

Paint source:
http://www.tubetape.net/servlet/the-5/greenscreen-screen/Detail

Disclaimer: I have not used this paint, it comes with no recommendations.


Removing an overlay using green screen footage? Ive got the composition, available publically:

And a green screen of the overlay used given from the Sea of Thieves 'Creator Crew' program.

How can I use this to remove the overlay from the fireplace, and fill in from other frames something passable.

What you are looking for is called "Chroma Keying".

It works by sampling a color (in either 2D or 3D space, but you don't have to worry about that) and it, simply put, exchanges that color with the alpha channel - thus making the hue transparent. If you're working with Streamlabs OBS, regular OBS, After Effects or something similar, Chroma Keying is built into these programs. For a good result and knowledge about screen mattes, despill and other things to keep in mind while keying, check out the tutorials by andrew kramer.


After Effects : shortcut for next keyframe on current layer? I know about the J and K shortcuts for the previous/next (visible) keyframe on the timeline.
I was wondering if there was something similar to reach the previous/next keyframe on the current layer.
Seems it exists for Flash (Animate CC) but can't find anything about it in After Effects.

Any idea ?

Thanks !

I don't believe there is a shortcut for this.

Here are a couple of 'near alternatives' that might help:
1. The keyframe navigator arrows on the property will jump you from one keyframe to the next on that property alone.
2. Drag the playhead while holding shift to snap to keyframes.


Is it possible to drop some specific frames when comparing SSIM by ffmpeg? I would like to calculate the SSIM for two videos by ffmpeg: the original video and the distorted video.
The case is the distorted video was generated by some kind of GPU of android devices, and it might miss some frames, for example, the original video has 720 frames, meanwhile the distorted one has 718.
Suppose we know the specific indices of the frames that was drop(For example, by calculating the MSE_U frame by frame), how to calculate the SSIM by ignoring some specific frames of the original video?
For example, we have know that the index 3 and index 717 was not exists in the distorted one, in order to SSIM, we should ignore these frames from the original one.
I've read the post Comparing PSNR/SSIM of two videos with different fps/bit-depth , drop similar frames and FFmpeg - dropping duplicate frames , it seems that they are not applying to my specific case.

Use the select filter to drop unwanted frames.
This is the basic syntax:
ffmpeg -i distorted -i ref -filter_complex "[0]settb=AVTB,setpts=N[ds];[1]settb=AVTB,select='not(eq(n\,3)+eq(n\,717))',setpts=N[rf];[ds][rf]ssim" -f null -


After effects loop part of movie clip I have one movie clip and it has few events which I want to repeat for few times. I used this and similar other tutorial to achieve this. Ideally I tried following,

Select Clip and Pre-compose it (so that I can use that repeating
part independently. I have tried without pre-compose also and got
same result)
Right click > time > enable time-remapping
Goto the expression panel (alt click clock symbol)
Put expression as loopOut() and click outside
Create keyframe between between start and end of my desired clip part

However, this doesn't work. Can anyone tell me what I am doing wrong?

To better explain the my desired output, lets assume I have 5 min video clip (===) and I want part from 3 to 4 min (+++) to repeat 2 times.

  0 ====3+++4====5

So now my video should become 6 min with clip from 3 to 4 min repeated twice.

  0 ====3+++4+++5====6

I am using Adobe After Effects CC 2019.

LoopOut() loops after the last keyframe, and by default it loops all the keyframes. Unless you have a specific need to use expressions, this would be easier to achieve by just setting keyframes.

Once you have time remapping enabled, go to the 3 minute mark and add a keyframe.
Then go to the frame one frame before 4 minute mark and add another.
Select the last three keyframes (3 minutes, 4 minutes and 5 minutes in your example).
Copy them ctrlc.
Delete the last keyframe
Park the playhead one frame after the 4 minute keyframe and paste ctrlv. The 3 minute keyframe should be at the exact 4 minute mark. Since the timing of the subsequent keyframes is undisturbed, the video will run at the right speed.

Your keyframes should look like this:

0=====3+++④3+++④=====5 ←keyframes
0.....3....4....5....6 ←time

(the ④ indicates the frame one frame before the four minute mark)

for extra credit change the first 4 minute keyframe (the one that has the 3 minute keyframe right after it) to a hold keyframe (Right-click and Toggle Hold Keyframe). This is because if you have motion blur or frame blending on it can cause strangeness as the layer is "rewound" between the two keyframes.


Select some pixels from imported movie to duplicate and stretch In Photoshop if you want to stretch some part of an image you can use the marquee tool to select the pixels you want, use Ctrl+J to duplicate and then Ctrl+T to stretch it.

I have a video recorded using a mobile phone in the vertical position and I want to do the same thing to repeat the sides of the video (it's a person talking and there's a painted wall behind him). Is it possible?

It is possible, but it might look a bit weird.  Video is constantly changing - even just a video of a wall will have noise in it, so static images tend to look a bit odd in comparison.  But Ii you stretch one pixel of the noisy moving image, you'll get lines of noise moving either side of your image, which might not look great either.

However, if you want to give it a go, duplicate your original image, use a mask to only show the edge that you want to extend, then adjust the scale in one dimension only (you'll need to click on the little link icon to only adjust the x-axis scale).

Alternatively, What many people do for a backdrop is to copy the image, scale it up to fill the screen, then blur, and darken it, and place it behind the original image.


Getting rid of a superimposed image? Is it possibile to cancel out an image superimposed on an another one if we know the overlaid image's alpha channel and pixel values?

It sounds like you're tying to remove a watermark from a copyrighted image.  The best way to do that is to pay the copyright owner for permission to use their image.


.wmv audio and .mov video out of sync I'm a total amateur at this video stuff.  I'm actually a web developer trying to create a video for work and I've run into a problem.  Hoping those of you who know stuff about videography can help me out. All of this to say, I apologize for the ignorance that follows:

I have video/audio recorded as .wmv and another video recorded as .mov.  I'm trying to overlap the .wmv audio with the .mov video.  It syncs up at the beginning of the video, but a few minutes in and it's off.  I have not cut the video yet except to line it up at the beginning.  I've successfully made a couple of basic videos like this in the past but I suspect it has something to do with the two different formats. I'm using Adobe Premiere Pro.  Google has no advice for me.  Does anyone know what I can do to fix this?

There are several possibilities here.  It could be that one device or both dropped frames and thus ended up out of sync, it could be a difference in frame rate or it could simply be that one or both devices have inaccurate internal clocks for recording.  Your best bet is to identify a point at the beginning and at the end of each video that should be the same.  Figure out the offset and then do a speed adjustment to one of the clips to make it line up with the other.

After you do this, the beginning and end should both match up, but you still want to make sure to watch the entire video closely to make sure it stays lined up the entire way through.  If the loss of sync was due to dropped frames rather than a difference in clock speed, the rate adjustment will not fix the problem and you'll see sync issues emerge somewhere in the middle of your video.

If it is due to loss of frames, there isn't a lot you can easily do to recover from the problem because you are missing the information that should be in those frames.  If it is an internal clock rate issue or an FPS issue, then there is a decent chance that the rate adjustment should fix it for you.


How to use ffmpeg to fade in/out a veriable frame rate video clip with unknown duration I have been looking for a way to use ffmpeg to downscale some MPEG-4 (Base Media / Version 2) video files recorded with a variable frame rate, adding fade in/out effects at the head and tail of each clip.

Based on the answer provided here, I've been using the following command line to add a 2 second fade/out effect on to my clips:

ffmpeg -i VID_1.mp4 -sseof -2 -copyts -i VID_1.mp4 -lavfi "[1]fade=out:s=0:d=2[tail];[0][tail]overlay,fade=in:s=0:d=2[overlay]; anullsrc,atrim=0:4[audiotail];[0][audiotail]acrossfade=d=2,afade=d=2[audio];[overlay]scale=640:-1[video]" -map "[video]" -map "[audio]" -vsync 2 -sws_flags gauss -c:v libx264 -crf 18 -preset slow -shortest -report -hide_banner VID_1_out.mp4

My questions:

I seem to get a lot of the following error lines in the report

cur_dts is invalid (this is harmless if it occurs once at the start per stream)

Is it normal?

In the resulting output video clip, the fade-in comes out less than 2 seconds (about 1 second), and there appears no fade out, just a black-out for the last four seconds. Where is my command line wrong?
The duration of the original clip is 24s640ms, the output file is longer by 2s022ms. Why additional 22 ms?

If I drop the -vsync 2 option, the output clip frame rate becomes exactly the same as that of the source video file. This, however doesn't deal away with the above issues.

This works here

ffmpeg -i VID_1.mp4 -sseof -2 -copyts -i VID_1.mp4 -lavfi "[1]fade=out:s=1:d=2[tail];[0][tail]overlay,fade=in:s=0:d=2,scale=640:-2[video];anullsrc,atrim=0:2.1[audiotail];[0][audiotail]acrossfade=d=2,afade=d=2[audio]" -map "[video]" -map "[audio]" -vsync 2 -sws_flags gauss -c:v libx264 -crf 18 -preset slow -shortest -report VID_1_out.mp4

With some videos, usually those with variable FPS, the fade filter only works with start frame as non-zero. Also, the anullsrc needs to be only slightly greater than the crossfade duration.