[FFmpeg-trac] #4158(undetermined:new): Audio Stream loss after codec change

[FFmpeg]

#4158: Audio Stream loss after codec change
-------------------------------------+-------------------------------------
             Reporter:  jimbob       |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:  Dolby,       |               Blocked By:
  Stereo, Audio, Surround Sound,     |  Reproduced by developer:  0
  Closed Captioning                  |
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 We are using ffmpeg to transcode live mpeg2 streams from satellite
 receivers to MP4 streams. Unfortunately reproducing the bug will be
 extremely difficult without a similar setup that we have.
 How to reproduce:
 {{{
 % ffmpeg -vsync 1 -i "udp://239.xxx.xxx.xxx:yyyy?overrun_nonfatal=1" -vf
 yadif -map 0 -c:a copy -vcodec libx264 -b:v 5000k -bufsize 12000k -g 60
 -preset superfast -f mpegts
 "udp://239.zzz.xxx.xxx:yyyy?pkt_size=1316&ttl=10"

 ffmpeg -version
 ffmpeg version 2.4.2 Copyright (c) 2000-2014 the FFmpeg developers
 built on Oct 30 2014 21:43:28 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
 configuration: --prefix=/home/user/ffmpeg_build --extra-
 cflags=-I/home/user/ffmpeg_build/include --extra-
 ldflags=-L/home/user/ffmpeg_build/lib --bindir=/home/user/bin --extra-
 libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-
 libfreetype --enable-libmp3lame --enable-libtheora --enable-libvorbis
 --enable-libvpx --enable-libx264 --enable-nonfree --disable-ffplay
 libavutil      54.  7.100 / 54.  7.100
 libavcodec     56.  1.100 / 56.  1.100
 libavformat    56.  4.101 / 56.  4.101
 libavdevice    56.  0.100 / 56.  0.100
 libavfilter     5.  1.100 /  5.  1.100
 libswscale      3.  0.100 /  3.  0.100
 libswresample   1.  1.100 /  1.  1.100
 libpostproc    53.  0.100 / 53.  0.100
 }}}

 Container: Mpeg2
 Audio Codec: Normally AC3.

 What we have been able to notice is with channels that change their audio
 format from Stereo to Dolby or vice versa: ffmpeg appears to drop the
 audio channel all together (Like it is muted muted or non-existent). We
 are able to listen to the Closed Captioning PID stream through out this
 whole time: this is likely because the enm source does not change format.
 Silencedetect and Volumedetect filters do not indicate that any problem
 exists with the volume on the output stream. However we have to restart
 the stream in order for it to start working again. Picture quality is
 phenomenal.

 For example: we're pulling a channel down from one of the various Movie
 Central's (It affects them all), after a few days to a week the audio will
 just stop working. We have been unable to identify exactly when it happens
 as we are unable to watch TV for days on end. We have ruled out that it is
 not our deployment: it's not our Set Top Boxes, or our delivery network.
 We have ruled out the source of the video stream and our set top boxes by
 using muticast capable computers and software.

 We suspect that it happens when a relatively new movie is played on this
 channel, it doesn't appear to affect movies from the early 2000's or
 older. (As we have gone through the program output for this specified time
 and looked through the channels. We have been unable to identify one
 particular movie that does it.)

 Volumedetect shows correct dB, Silencedetect does not detect any silence
 of the audio.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4158>
FFmpeg <https://ffmpeg.org>
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