[Live-devel] MP4 Video Startup Issue

[Warren Young]

On Aug 23, 2018, at 1:13 PM, Bill Barnett <Bill.Barnett at jasniksolutions.com> wrote:
> 
> We are looking for help to determine why the first 7 to 10 seconds of mp4 data video is not displayed in most instances.

Tell whoever wrote that interface that “NTSC” and “720p” are incompatible terms.

As to your question, it’s obvious from the I-frame interval settings combined with the frame rate.  The -f flag you gave tells it to select the 10 fps stream, which only puts out a fresh I frame every 10 seconds, given 100 frame GOPs and 10 fps.  Until you get a closed GOP and a fresh I frame, the decoder can’t begin decoding, lacking references for most of the delta frame data.

If you want low latency video, you must use a shorter GOP.  That will require a higher encoding bit rate to get equivalent perceived quality.  TANSTAAFL.