[MPlayer-dev-eng] MIPS and colorspace conversion

[D Richard Felker III]

On Tue, Dec 16, 2003 at 04:27:21PM -0800, Josh Green wrote:
> I wrote this list just recently about getting higher performance with an
> FPU-less 400MHz MIPS board. I did some profiling with mplayer on a P-II
> 366 laptop, and disabled MMX in mplayer to try get the same code path
> (report at end of email). The summary of this test is essentially what I
> was told before, that the colorspace conversion (to the fbdev) is likely
> killing most of the CPU time.
> 
> I've looked over the macros for creating the yuv2rb_c_* routines, but I
> have yet jumped into the MIPS assembler to see if any optimization can
> be done (I doubt much can be gained there, but I will check out the
> assembler output for that routine).
> 
> Before seeing about assembler optimization for the mips, I wanted to ask
> if anyone knows of a good quality video format that could be played with
> mplayer that has native BGR output? Looking through the codecs.conf it
> appears there are lots of codecs that have BGR output, but I didn't find
> one that I could encode to easily, to see if colorspace conversion could
> be done away with.

No, there are no codecs that use BGR and get decent compression,
because BGR is a very inefficient space to work in. If you want to
experiment, you could use huffyuv or lossless mjpeg in BGR mode, but
the bitrates you need with these will be 10-50x what you'd need with
mpeg4.

> Thanks in advance for any ideas about how I can get some decent
> resolution video (640x480 or larger) to play on this thing :) Cheers.

Optimize yuv2rgb_c_16 or be content with black&white output. (Writing
a fast grayscale YUV to BGR converted is trivial! :)

Rich