[Ffmpeg-devel] libavcodec & XVMC

Ivan Kalvachev ivan
Thu Apr 21 18:45:22 CEST 2005

On Wed, 20 Apr 2005 09:24:55 -0600
Mike Melanson <mike at multimedia.cx> wrote:

> castet.matthieu at free.fr wrote:
> > Hi,
> > Selon Thomas Herrmann <ollo.diab at gmx.de>:
> > 
> > 
> >>Hi developers,
> >>
> >>I would like to understand the status of XVMC support in libavcodec. The
> >>configure script in the current CVS does not support the XVMC option, but
> >>still if one does set HAVE_XVMC_ACCEL=yes in config.mak the xvmc* files get
> >>build and linked into libavcodec.
> >>
> >>My question is, what is needed from the application side to get XVMC support
> >>out of libavcodec?
> >>
> > 
> > You could look how mplayer use it...
> > Xine support XCMC, but I don't know if they use ffmpeg for that...
> 	No, xine does not use XvMC via FFmpeg. Not sure about all the design 
> decisions behind it but this comes from xine's FFmpeg diff file for the 
> file avcodec.h:
> +/* FIXME: We cannot use ffmpeg's XvMC capabilities, since that would 
> require
> + * linking the ffmpeg plugin against XvMC libraries, which is a bad thing,
> + * since they are output dependend.
> + * The correct fix would be to reimplement the XvMC functions 
> libavcodec uses
> + * and do the necessary talking with our XvMC output plugin there. */
> +#undef HAVE_XVMC

I would be happy to hear what kind of changes are required.

I had taken an special care no XvMC functions to be used in libavcodec,
all you need are the XvMC headers. 
Linking libavcodec to XvMC lib is also output dependent and is plain wrong.
Linking XvMC with video decoder plugin is a matter of design.
MPlayer video output module is the one that uses XvMC functions.

So xine problem is xine problem. And it looks like "we do it our way" problem.

As You Wish
   Ivan Kalvachev

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