[Ffmpeg-devel] Re: [PATCH] wav tag

[Michael Niedermayer]

Hi

On Wed, Mar 01, 2006 at 04:05:13PM +0100, Baptiste COUDURIER wrote:
> M?ns Rullg?rd wrote:
> > Baptiste COUDURIER said:
> > 
> >>Michael Niedermayer wrote:
> >>
> >>>[...]
> >>>
> >>>rejected, a muxer MUST always honor codec_tag, the bug is that codec_tag is
> >>>blindly copied from the demuxer to the muxer context
> >>>
> >>
> >>All right. Shouldn't codec_tag be blindly copied ? We have to in case of
> >>an unrecognized fourcc, no ? We got here a fourcc collision between
> >>formats. How can that be fixed ?
> > 
> > 
> > WAV doesn't use fourcc.  It uses a 16-bit integer.  Some form of mapping
> > is required.
> > 
> 
> Yes, atm WAV muxer uses codec->codec_tag if it is set. MOV demuxer sets
> fourcc as codec_tag. Where correct remapping should be done when using
> stream copy ?
> 
> Since michael said remapping in wav muxer was wrong, maybe I misunderstood ?

iam not sure which method is best, just that your solution is not ok

maybe the codec_tag-codec_id-... table should be available through AVFormat*
that way an application like ffmpeg could check 
if the codec_tag is supported -> copy codec_tag
else if the codec_id is supported -> codec_tag=0
else just copy codec_tag and warn user

[...]

-- 
Michael