Re: Video Overlay on C3200

On Monday 12 March 2007 11:18, Tim Chick wrote:
> > > On Fri, Mar 02, 2007 at 01:53:34PM +0000, Tim Chick wrote:
> > > You mean by say doubling every pixel? I guess this would be just about
> > > possible, but how would it help? Everything gets better (because of DMA
> > > load) in lower resolution. Why not just swap res?
> >
> > No I mean for people playing DivX files coming from Bittorrent backup
> > systems which seem to use 512x384 or 640x480 quite commonly.
>
> I did some investigation with the files Graeme sent me for testing. They
> were 16:9 format around 640 pixels wide.
>
> I also discovered that only the mpeg1 and mpeg2 code has significant arm
> optimisations - the mpeg4 stuff is using plain c versions, so I suspect
> with a bit of work it would be possible to get these large files to play.

I looked into it further, and did some experiments with the cacko mplayer.

The cacko mplayer is compiled with iwmmxt - you need this to get the MPEG4 arm 
assembler. I did not realise the h263 function was being used for h264, along 
with some of the other stuff iwmmxt implements.

So we just need to build for iwmmxt. When I tried this it crapped out, so I 
rebuilt just that file with -mcpu xscale, which produced a binary which 
causes alignment traps which are not fixed up.

Building for iwmmxt will not quite get us there I suspect - the cacko mplayer 
was significantly better when overclocking - it appeared to be the sdram 
which was the bottle neck (no real surprise). Increasing the cpu clock did 
not make much difference, but setting 520/160/130 got the video decode going 
with about 25% of the cpu to spare - enough for the video copy and audio 
decode (I did my tests with cropped video and audio turned off)

Has anyone built a working iwmmxt mplayer for OZ?

Thanks,
Tim


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