qtdemux: stbl_index is valid from 0 onwards
qtdemux: stbl_index is valid from 0 onwards

It indicates the last sample parsed, not the next one to parse.
As it starts in -1, any value from 0 onwards means that it has
some valid data.

shelsonjava/gst-plugins-good,froggatt/gst-plugins-good-m,StreamUtils/gst-plugins-good,GStreamer/gst-plugins-good,BigBrother-International/gst-plugins-good,BigBrother-International/gst-plugins-good,GStreamer/gst-plugins-good,BigBrother-International/gst-plugins-good,hizukiayaka/gst-plugins-good,Kurento/gst-plugins-good,froggatt/gst-plugins-good-m,kittee/gst-plugins-good,vatavuserban/gst-plugins-good,Kurento/gst-plugins-good,GStreamer/gst-plugins-good,GrokImageCompression/gst-plugins-good,rawoul/gst-plugins-good,shelsonjava/gst-plugins-good,rawoul/gst-plugins-good,Kurento/gst-plugins-good,chamois94/gst-plugins-good,sebras/gst-plugins-good,GrokImageCompression/gst-plugins-good,rawoul/gst-plugins-good,froggatt/gst-plugins-good-m,shelsonjava/gst-plugins-good,ikonst/gst-plugins-good,kittee/gst-plugins-good,BigBrother-International/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,kittee/gst-plugins-good,StreamUtils/gst-plugins-good,stfl/gst-plugins-good,stfl/gst-plugins-good,sebras/gst-plugins-good,StreamUtils/gst-plugins-good,Kurento/gst-plugins-good,StreamUtils/gst-plugins-good,ikonst/gst-plugins-good,froggatt/gst-plugins-good-m,kittee/gst-plugins-good,shelsonjava/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,hizukiayaka/gst-plugins-good,vatavuserban/gst-plugins-good,chamois94/gst-plugins-good,hizukiayaka/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,sebras/gst-plugins-good,vatavuserban/gst-plugins-good,chamois94/gst-plugins-good,Kurento/gst-plugins-good,rawoul/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,stfl/gst-plugins-good,chamois94/gst-plugins-good,GrokImageCompression/gst-plugins-good,hizukiayaka/gst-plugins-good,pexip/gst-plugins-good,stfl/gst-plugins-good,ikonst/gst-plugins-good,ikonst/gst-plugins-good,GStreamer/gst-plugins-good,GrokImageCompression/gst-plugins-good,sebras/gst-plugins-good,vatavuserban/gst-plugins-good,pexip/gst-plugins-good