[Ffmpeg-devel] [PATCH] xan_dpcm in MPlayer + libavformat

[Michael Niedermayer]

Hi

On Sat, Nov 18, 2006 at 06:02:50PM +0000, M?ns Rullg?rd wrote:
> Diego Biurrun <diego at biurrun.de> writes:
> 
> > On Sat, Nov 18, 2006 at 03:20:24AM +0100, Michael Niedermayer wrote:
> >> 
> >> On Fri, Nov 17, 2006 at 05:17:58PM -0800, Mike Melanson wrote:
> >> > Diego Biurrun wrote:
> >> > >IIUC MPlayer falls back on codec_id if codec_tag is not set.  The
> >> > >problem is that these AVI files mark the xan_dpcm audio as 0x1 (or was
> >> > >it FourCC Axan + TwoCC 0x1 Roberto?), which is PCM.  I don't think there
> >> > >is a way to support this without hacks..
> >> > 
> >> > Right. The people (Origin) that developed this format never applied with 
> >> > Microsoft for a specific codec ID; they didn't mean for these files to 
> >> > be played in general media players. They have codec ID 0x0001 (usually 
> >> > reserved for PCM). There is data elsewhere in the AVI file indicating 
> >> > 'Axan'. All written up here:
> >> 
> >> AVCodecContext.stream_codec_tag i assume, and i would appreciate it if
> >> someone would remove this dirty "if video is xan then audio is so too"
> >> hack and instead add Axan to riff.c and check both stream_codec_id and
> >> codec_id
> >
> > Dunno if I understood you correctly (probably not), but here is a patch
> > that contains the hack a bit more based on your suggestion to check
> > stream_codec_tag.  It's better than it was before at least.
> 
> What is the meaning of stream_codec_tag?  The official microsoft docs
> are rather fuzzy on this topic.

hmm the way i interpret them is that the normal fourcc/twocc specifies the
format and the fccHandler/stream_codec_tag specifies the prefered
implementation which should be used to decode it
now if my interpretation is correct and i think so (the text isnt so fuzzy)
then this has little to do with what people put into these fields ...

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
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