[MPlayer-users] xvmc in MPEG4 Re: MPlayer-users Digest, Vol 18, Issue 11

[Rich Felker]

On Wed, Jun 08, 2005 at 05:21:02PM +0300, Jouni.Lohikoski at iki.fi wrote:
> >    6. Re: about -vo xvmc and -vc ffmpeg12mc, mplayer options (sinan ,)
> > On 6/7/05, RC <rcooley at spamcop.net> wrote:
> > > xvmc only works with MPEG-1/MPEG-2 videos.
> 
> Would it be difficult to make it work also for MPEG4?
> Would some kind of transcoder codec change MPEG4-type of workload to
> MPEG2-type and then use XVMC, and still save lots of CPU cycles ?

No, it would use 3x as many cpu cycles.

> I am not expert in MPEG-encoding algorithms, but isn't there same kind
> of IDCT and motion predicting done in MPEG2 and MPEG4 when decoding?

The problem is there are additional things in MPEG4 which cannot be
done efficiently with MPEG2 operations. If this weren't the case
there'd be no point in MPEG4, since it would be the same as MPEG2.

Rich