[Ffmpeg-devel] DVR-MS bug (MP2 decoding)

[Steve Lhomme]

John Donaghy wrote:
>>>> So I assume it's MP2 and not AC3.
>>> You're right, I looked at it in GraphEdit and on my machine it chooses
>>> my InterVideo audio decoder for this file rather than the regular MPEG
>>> Audio Decoder. The properties dialog for the Intervideo decoder calim
>>> it is '2 speaker mode, Dolby Sound compatible (as opposed to
>>> stereo/mono). It says the format is MPEG2 and the attributes are
>>> 16bit/48k/1ch. I wonder what is different about this audio stream that
>>> causes it to pick the Intervideo decoder - maybe the 'dolby' setting?
>> All I know is that it's not AC3. DScaler has an input type
>> MEDIATYPE_DVD_ENCRYPTED_PACK instead of MEDIATYPE_Audio, that could be
>> the difference.
> 
> I'm afraid I've got no more ideas about this. I looked at what the
> code was doing and the demuxer reports it as an mp2 stream which is
> presumably correct. Then the mp3 lib code makes a call to 'read_frame'
> which repeatedly calls 'decode_header' to try to find a valid header
> without success. libmad.a also fails in that it plays some strange
> noises instead of the real audio stream.
> 
> I'm curious though, does DScaler play dvr-ms files or did you convert
> the file first?

It decodes the original audio stream (presumably MP2) just fine. Maybe 
one day when I have time I'll try to compile DScaler and see what it's 
using. But not in the short term future...

Steve

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