mts: MTS discontinuities prevent video from playing when streaming over HLS

[Alan Noble]

We are using hls.js to play and we sometimes get zero PTS value warnings and other warnings mid-stream.

I added an clip period (cp) option to vidgrind's m3u output mode to generate clips of an arbitrary period, i.e.,

http://vidgrind.appspot.com/play?ma=00:00:00:00:00:01&pn=V01&output=m3u&cp=50

When the MTS is returned as a single file to the hls player we still get this warning:

[warn] > missing video frame(s) on first frag, appending with gap 0

You can play HLS at the following URL:

http://vidgrind.appspot.com/static/play.html?http://vidgrind.appspot.com/play?ma=00:00:00:00:00:01&pn=V01&output=m3u&cp=50

The underlying MTS file is: http://vidgrind.appspot.com/play?ma=00:00:00:00:00:01&pn=V01&ts=1545359624,1545359674

This is 50s of video taken from testTimestamped.ts, starting from the first PMT record. Records prior to the first PMT were discarded.

VLC will play this file, but there are many warnings, notably:

ts warning: discontinuity received 0x0 instead of 0x7 (pid=0)

vlc.log attached.

[Alan Noble]

This is likely due to discontinuities in the MTS data. VLC reports such discontinuities but carries on regardless, but hls.js croaks.

[Saxon Milton]

This was addressed in PR #9 on iotsvc, however work needs to be done on revid such that the discontinuity indicator is set when a discontinuity occurs.