Re: Video Overlay on C3200

> > 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.

Unfortunately they need about 130% of the CPU to *just* decode MPEG4 to YV12, 
so there is little I can do in my display driver to get them working. They 
will play if you get mplayer to drop the resolution during decode, but the 
results are pretty horrible.

eg
mplayer -vo pxa -vm -lavdopts lowres=1 -noslices big_file.avi

I had a dig around in the mplayer code. I think the lowres option looks so bad 
is that it is not fully implimented in the libavcodec code.

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. When I 
get a chance I'm going to look at the libavcodec stuff, to implement some of 
the functions in arm assembler, but don't hold your breath! I imagine it will 
also be needed to overclock the zaurus. With standard clock rates the audio 
needs about 10%, and the video driver something like 20% at these 
resolutions, so we have 70% of the cpu left, which would mean doubling the 
speed of the existing code!

Graeme, do you think you could chuck my latest driver code into monotone?

Thanks,
Tim


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