Audio Stream loss after codec change
|Reported by:||Jim||Owned by:|
|Blocking:||Reproduced by developer:||no|
|Analyzed by developer:||no|
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
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.
Change History (10)
comment:1 by , 9 years ago
|Keywords:||Dolby Stereo Audio Surround Sound Closed Captioning removed|
|Priority:||important → normal|
comment:4 by , 8 years ago
|Status:||closed → reopened|