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

Måns Rullgård mru
Wed Sep 21 22:29:40 CEST 2005

M?ns Rullg?rd <mru at inprovide.com> writes:

> 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?

Oh, and I'm obviously looking into a fix for lavf to detect this.

M?ns Rullg?rd
mru at inprovide.com

More information about the ffmpeg-devel mailing list