question: What is the relationship between resolution, frame height and width, data rate and file size?
comment: > What is the relationship between resolution, frame height and width... Aspect Ratio is the numerical way of expressing the difference between the width and height of an image. For instance, an image with a resolution of 1920x1080 has an Aspect Ratio of 1.78:1, meaning it is 1.78 times wider than tall; this is also sometimes expressed as "16:9". Every resolution is tied to a specific Aspect Ratio, i.e. 1080p will *always* have an aspect of 1.78:1. However, this rule doesn't remain true "in reverse", which is to say that a given Aspect Ratio isn't tied to any one specific resolution. For instance, an image captured at 3840x2160 has double the amount of both horizontal and vertical resolution that 1080p offers, but the aspect ratio remains at 1.78:1, and likewise, 720p also yields a 1.78:1 asepct, it's simply a matter of maintaining the ratio as resolution goes up or down. For the sake of comparison, old "square TVs" (they aren't actually perfectly square) have an AR of 1.33:1, and the "defacto standard" for motion pictures was 1.85:1 for many decades, although other filming standards exist as well. > But then why are some videos of the same resolution (and approximately same duration) so different in file size? Different codecs reduce video size to different degrees and using different methods, so depending on how the video was encoded, you can maintain common resolution while file sizes change. > I am guessing it has got to do with the data rate, but how does it actually work? Data rate (bitrate) can be a *part* of it, but it's not the entire story; it is possible for a given codec to use more aggressive or less aggressive compression than another comparable codec without the bitrate changing. So, it's possible for 2 videos to both be encoded at 1080p at the same bitrate, but with one using more aggressive/less efficient compression that will visibly degrade video quality and/or cause issues like mpeg blocking, etc... Essentially, compression scheme, resolution, and bitrate all effect how video quality works independently of one another. There were some interesting DVD releases marketed under the name "Superbit" that omitted bonus material in lieu of using the additional disc space to encode at a higher bitrate. The resolution and encoding scheme didn't change, but they were able to realize improved A/V quality through the use of a higher than normal bitrate. > If I have a 1920x1080 video with an initial data rate of 8160 kbps and send it through a file converter such that it has a new lower data rate, does it affect the video quality in any way? Yes, as bitrate drops, so does video quality, but whether the difference is noticeable depends on specifics not addressed here. > Can it still be considered 1080p? Yes, if a video file has a resolution of 1920x1080 and is "progressive" (non-interlaced), it is a 1080p image regardless of anything else.
passages: Section::::Video frames.:Viewing distance.
  
  The key parameter to determine the lowest resolution still satisfactory to viewers is the viewing distance, i.e. the distance between the eyes and the monitor. The total resolution is inversely proportional to the square of the distance. If d is the distance, r is the required minimum resolution and k is the proportionality constant which depends on the size of the monitor;
  
  Since the number of lines is approximately proportional to the resolution per line, the above relation can also be written as
   Where :
  
  "vSPI" is the vertical SPI
  
  "hSPI" is the horizontal SPI (can be considered the same as vSPI if not specified specifically)
  
  "area" is the squared area of the scanned document in inches²
  
  "color depth encoding" is the number of bits used to encode a given amount of color information (256 colors=8; 65'536 colors=16; 16million colors=24)
  
  Remember that this will give raw data bytes, images are almost always compressed when saved to disk using lossless (like PNG, TIFF) or lossy image formats (like JPEG).
  
  Section::::See also.
  
  BULLET::::- dots per inch
  
  BULLET::::- pixels per inch
  
  BULLET::::- lines per inch
   where n is the number of lines. That means that the required resolution is proportional to the height of the monitor and inversely proportional to the viewing distance.
  
  Section::::Video frames.:Moving picture.
   BULLET::::- Display resolution is the number of distinct pixels in each dimension that can be displayed. For a given display size, maximum resolution is limited by dot pitch.
  
  BULLET::::- Dot pitch is the distance between sub-pixels of the same color in millimeters. In general, the smaller the dot pitch, the sharper the picture will appear.
  
  BULLET::::- Refresh rate is the number of times in a second that a display is illuminated. Maximum refresh rate is limited by response time.
   The following table show how pixel density is supported by popular image file formats. In the second column, "length" refers to horizontal and vertical size in inches, centimeters, etc., whereas "pixel" refers only to the number of pixels found along the horizontal and vertical dimension. The cell colors used do not indicate how feature-rich a certain image file format is, but what density support can be expected of a certain image file format. Often-used image file formats that do not support pixel density are added for counter-example purposes.
   TVL is defined as the maximum number of alternating light and dark vertical lines that can be resolved per picture height. A resolution of 400 TVL means that 200 distinct dark vertical lines and 200 distinct white vertical lines can be counted over a horizontal span equal to the height of the picture. For example, on monitor with 400 TVL, 200 vertical dark lines can be counted over width on monitor (Note that the of monitor height is used rather than the of whole monitor width).
   Section::::Overscan amounts.
  
  There is no hard technical specification for overscan amounts for the low definition formats. Some say 5%, some say 10%, and the figure can be doubled for title safe, which needs more margin compared to action safe. The overscan amounts are specified for the high definition formats as specified above.
  
  Different video and broadcast television systems require differing amounts of overscan. Most figures serve as recommendations or typical summaries, as the nature of overscan is to overcome a variable limitation in older technologies such as cathode ray tubes.
   For transmission, there is a physical connector and signal protocol (see List of video connectors). A given physical link can carry certain display standards that specify a particular refresh rate, display resolution, and color space.
   BULLET::::- Frame rate is identified as number of video frames per second. For interlaced systems, the number of frames per second should be specified, but it is not uncommon to see the field rate incorrectly used instead.
  
  If all three parameters are used, they are specified in the following form: "[frame size][scanning system][frame or field rate]" or "[frame size]/[frame or field rate][scanning system]". Often, frame size or frame rate can be dropped if its value is implied from context. In this case, the remaining numeric parameter is specified first, followed by the scanning system.
   BULLET::::- 580×480 : Super VHS, Hi8, LaserDisc
  
  BULLET::::- 700×480 : Enhanced Definition Betamax, Analog broadcast limit (NTSC)
  
  BULLET::::- 768×576 : Analog broadcast limit (PAL, SECAM)
  
  BULLET::::- Digital
  
  BULLET::::- 500×480 : Digital8
  
  BULLET::::- 720×480 : D-VHS, DVD, miniDV, Digital Betacam (NTSC)
  
  BULLET::::- 720×480 : Widescreen DVD (anamorphic) (NTSC)
  
  BULLET::::- 720×576 : D-VHS, DVD, miniDV, Digital8, Digital Betacam (PAL/SECAM)
  
  BULLET::::- 720×576 : Widescreen DVD (anamorphic) (PAL/SECAM)
  
  BULLET::::- 1280×720 : D-VHS, HD DVD, Blu-ray, HDV (miniDV)
  
  BULLET::::- 1440×1080 : HDV (miniDV)
  
  BULLET::::- 1920×1080 : HDV (miniDV), AVCHD, HD DVD, Blu-ray, HDCAM SR
  
  BULLET::::- 1998×1080 : 2K Flat (1.85:1)
   BULLET::::- Gamut is measured as coordinates in the CIE 1931 color space. The names sRGB or AdobeRGB are shorthand notations.
  
  BULLET::::- Aspect ratio is the ratio of the horizontal length to the vertical length. Monitors usually have the aspect ratio , , or .
  
  BULLET::::- Viewable image size is usually measured diagonally, but the actual widths and heights are more informative since they are not affected by the aspect ratio in the same way. For CRTs, the viewable size is typically smaller than the tube itself.
   The exact width is determined by taking the definition of the time required for an active line in PAL or NTSC, and multiplying it by the pixel clock of 13.5 MHz of Digital SDTV. PAL is exactly 52μs, so it will equate to exactly 702 pixels.
   B/G/I/K television system signals (usually used with PAL colour encoding) transmit frames less often (50 Hz), but the frame contains more lines and is wider, so bandwidth requirements are similar.
  
  Note that a "discernible line" forms one half of a cycle (a cycle requires a dark and a light line), so "228 cycles" and "456 lines" are equivalent measures.
  
  Section::::System resolution.
   The act, process, or capability of distinguishing between two separate but adjacent parts or stimuli, such as elements of detail in an image, or similar colors.
  
  Section::::R.:Resolution (horizontal).
  
  The amount of resolvable detail in the horizontal direction in a picture. It is usually expressed as the number of distinct vertical lines, alternately black and white, which can be seen in a distance equal to picture height.
  
  Section::::R.:Resolution, Limiting.
   Another qualifying parameter for a scanner is its "resolution", measured in pixels per inch (ppi), sometimes more accurately referred to as Samples per inch (spi). Instead of using the scanner's true optical resolution, the only meaningful parameter, manufacturers like to refer to the "interpolated resolution", which is much higher thanks to software interpolation. , a high-end flatbed scanner can scan up to 5400 ppi and drum scanners have an optical resolution of between 3,000 and 24,000 ppi.
   There are four basic display sizes for ATSC, generally known by referring to the number of lines of the picture height. NTSC and PAL image sizes are smallest, with a width of 720 (or 704) and a height of 480 or 576 lines. The third size is HDTV images that have 720 scan lines in height and are 1280 pixels wide. The largest size has 1080 lines high and 1920 pixels wide. 1080-line video is actually encoded with 1920×1088 pixel frames, but the last eight lines are discarded prior to display. This is due to a restriction of the MPEG-2 video format, which requires the height of the picture in luma samples (i.e. pixels) to be divisible by 16.
   BULLET::::- 8K UHD (7680 × 4320 progressive scan)
  
  Section::::Current standards.:Computer monitors.
  
  Computer monitors have traditionally possessed higher resolutions than most televisions.
  
  Section::::Current standards.:Computer monitors.:2000s.
  
  , 1024 × 768 eXtended Graphics Array was the most common display resolution. Many web sites and multimedia products were re-designed from the previous 800 × 600 format to the layouts optimized for 1024 × 768.
   Section::::Home and professional recording.:New standards: SuperBetamax and Extended Definition Betamax.:Comparison with other video formats.
  
  Below is a list of modern, digital-style resolutions (and traditional analog "TV lines per picture height" measurements) for various media. The list only includes popular formats. Note that listed resolution applies to luminance only, with chroma resolution usually halved in each dimension for digital formats, and significantly lower for analog formats.
  
  Equivalent pixel resolutions are calculated from analog line resolution numbers:
   Section::::Video standards.:Standard definition video.
  
  Standard definition rips have a resolution that is lower than high-definition video.
  
  Section::::Video standards.:Standard definition video.:DivX and Xvid for retail and bootleg sources.
   Section::::Video images.:Apple II.:High-resolution graphics (HGR).:File format.
   BULLET::::1. "Rec.601", a Rec.601-compliant value, which is considered the real pixel aspect ratio of standard-definition video of that type.
  
  BULLET::::2. "Digital", which is roughly equivalent to Rec.601 and is more suitable to use in Digital Video Editing software.
   The BMHD chunk specifies how the image is to be displayed and is usually the first chunk inside the FORM. It not only defines the image's height/width, but where it is drawn on the screen, how to display it in various screen resolutions and if the image is compressed. The content of this chunk is as follows:
  
  Section::::File format.:BODY: Image data.
  
  The BODY chunk is usually the last chunk in a file, and the largest.
   Section::::Measuring optical resolution.:EIA 1956 video resolution target.
  
  The EIA 1956 resolution target was specifically designed to be used with television systems. The gradually expanding lines near the center are marked with periodic indications of the corresponding spatial frequency. The limiting resolution may be determined by inspection. The most important measure is the limiting horizontal resolution, since the vertical resolution is typically determined by the applicable video standard (I/B/G/K/NTSC/NTSC-J).
  
  Section::::Measuring optical resolution.:IEEE Std 208-1995 target.
  
  The IEEE 208-1995 resolution target is similar to the EIA target. Resolution is measured in horizontal and vertical TV lines.
  
  Section::::Measuring optical resolution.:ISO 12233 target.
   Consider that a single frame in a DI project is currently from 9MB to 48MB large (depending upon resolution and colour-depth), whereas video refresh rate is commonly 24 or 25 frames per second (if not faster); any storage required for real-time playing such contents thus needs a minimum overall throughput of 220MB/s to 1.2GB/s, respectively. With those numbers, all the above requirements (particularly file contiguity, given nowadays storage performances) become strictly mandatory.
  
  Section::::External links.
   For full-frame 35 mm format (24 mm × 36 mm, 43 mm diagonal), a widely used CoC limit is "d"/1500, or 0.029 mm for full-frame 35 mm format, which corresponds to resolving 5 lines per millimeter on a print of 30 cm diagonal. Values of 0.030 mm and 0.033 mm are also common for full-frame 35 mm format.
  