[Ffmpeg-devel] An MPEG2/AC3 audio that ffmpeg cannot properly identify (or play)

Bill May wmay
Wed Sep 21 22:16:31 CEST 2005

Ronen Mizrahi wrote:
> Hi,
> I have an MPEG2 file recorded from an Australian DVB-T broadcast. When 
> running ffmpeg -i on it this is what I get:
> ffmpeg version 0.4.9-pre1, build 4723, Copyright (c) 2000-2004 Fabrice 
> Bellard
>  built on Sep  7 2005 17:43:26, gcc: 3.2.3 (mingw special 20030504-1)
> Input #0, mpeg, from 'd:\testmedia\Avril Lavigne test 2.MPG':
>  Duration: 577014:01:50.9, bitrate: N/A
>  Stream #0.0: Video: mpeg2video, 720x576, 25.00 fps
> Must supply at least one output file
> As you can see the audio stream is not identified, I know this is not 
> the latest build, but if I am not mistaken not much has changed with 
> regard ot mpeg2 and I tested also MPlayer and latest release of VLC and 
> both of them fail to play the audio. Mplayer Classic on the other hand 
> (as well as Windows Media Player or any other directshow based player) 
> can play the audio just fine.
> If you would like you can download a sample from:
> http://www.tversity.com/ffmpeg/test.mpg

The substream value is 0xb, instead of 0x80 to 0x90 which would
be required for AC3.  (substream is the value after the PES header),
values 0x80 to 0x90 indicate AC3, 0xa0 to 0xb0 indicate LPCM.

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