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

[Måns Rullgård]

Bill May <wmay at cisco.com> writes:

> 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.

That's only for DVD.  In general, private stream 1 can contain
anything.  In this case it contains raw ac3 audio, no substreams or
such things.

What is the exact origin of this file?  DVB typically uses MPEG-TS,
but this is MPEG-PS.  Has it been remuxed?  What software did you use
to grab it?

-- 
M?ns Rullg?rd
mru at inprovide.com