Audio not working after broadcast dropped stream for couple of minutes

[mythtv@…]

Last week I recorded a show which the TV company accidentally screwed up the transmission so the first 10 minutes did not have any audio stream or zero channels as ffmpeg tells me after I split up the mpg into 10 minutes chunks.

From the silent 10 minutes chunk

    Stream #0.0[0x202]: Video: mpeg2video (Main), yuv420p, 720x576 [PAR 64:45 DAR 16:9], 8400 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0xbd3](fin): Subtitle: dvbsub
    Stream #0.2[0xbd4](swe): Subtitle: dvbsub
    Stream #0.3[0x1389](fin): Subtitle: [6][0][0][0] / 0x0006
    Stream #0.4[0x29e](swe): Audio: mp3, 0 channels

From a chunk with sound

    Stream #0.0[0x202]: Video: mpeg2video (Main), yuv420p, 720x576 [PAR 64:45 DAR 16:9], 8400 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x29e](swe): Audio: mp2, 48000 Hz, stereo, s16, 224 kb/s
    Stream #0.2[0xbd3](fin): Subtitle: dvbsub
    Stream #0.3[0xbd4](swe): Subtitle: dvbsub
    Stream #0.4[0x1389](fin): Subtitle: [6][0][0][0] / 0x0006

But in 24-fixes we'll never get back audio after these ten minutes when the audio comes back in the transmission.

I always record 2 minutes early and in those 2 minutes the audio works, so when I rewind to the beginning I still get no audio which I had when I started the recording.

I'll set minor prio on this as this was a human error on the TV company.

[markk]

Can you post the first 11 minutes or so of that recording? (or more importantly a clip that covers no audio to audio now transmitted).

Both master and 0.24/fixes should both handle that transition without issue - though the fact that the total number of streams hasn't changed may be confusing the decoder (or that its changing the audio from 0 channels to 2).

[mythtv@…]

Here is a gzipped clip, 18Mb.

​http://213.250.69.122/broken.mpg.gz

Hopefully it's good enough.

[markk]

Tested on 2 systems here (one with normal alsa stereo output and the other using HDMI audio).

There is no audio at first, a stream change is then detected about 5 seconds in and both systems then play audio as normal (although the audio stream is still reported as 0 channel).

Not sure if this is an ffmpeg update in trunk or some fix that Jean-Yves has added (or perhaps audio configuration/setup related) - so assignig to jya.

[JYA]

Can't reproduce in 0.27.1, audio comes back after a few seconds