[Ffmpeg-devel] An MPEG2/AC3 audio that ffmpeg cannot properly identify (or play)
Thu Sep 22 02:34:00 CEST 2005
Thank you, I guess the reason directshow and the recent version of
MPlayer work is because they have some heuristic that tries to determine
the correct audio codec to apply in case the substream value is invalid
or does not match the stream. I also guess that ffmpeg does not do it,
or maybe it does have some advanced mechanism to guess the proper audio
codec and I am just not aware of it?
Bill May wrote:
> Ronen Mizrahi wrote:
>> 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:
> 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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