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

John Donaghy johnfdonaghy
Mon Apr 24 17:50:13 CEST 2006

> I get the source width/height from AVCodecContext* catched as this:
> video_codec = avctx->streams[vidTrackId]->codec;

Thanks for that.

> >> 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?

> > Have to been able to play other HD dvr-ms files successfully?
That's good to know anyway.



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