[maemo-developers] N800 & Video playback

From: Daniel Stone daniel.stone at nokia.com
Date: Wed May 2 12:39:34 EEST 2007
On Wed, May 02, 2007 at 09:16:01AM +0300, ext Siarhei Siamashka wrote:
> On Tuesday 01 May 2007 20:49, Siarhei Siamashka wrote:
> > Results with unpatched xserver and some more explanations can be found in
> > [3]. 
> > Yes, now N800 is faster than Nokia 770 for video output performance at 
> > last :)
> Well, still not everything is so good until the following bug gets fixed:
> https://maemo.org/bugzilla/show_bug.cgi?id=1281
> The patch for optimized Xv performance will not help to watch widescreen
> video which triggers this tearing bug. If you see tearing on the screen, you
> should know that the YUV420 color format conversion optimization patch 
> does not  get used at all and xserver most likely uses a slow nonoptimized
> YUV422 fallback code with software scaling.

Indeed.  And the reason the code is there is because Hailstorm can only
downscale at fixed ratios (half and one-quarter), and even then, it
locked up when we tried.  Similarly, the display controller's
downscaling didn't work, either.  So we can optimise the fallback path,
but you'll still be screwed by sending 16bpp (instead of 12bpp) through

> Fixing this bug is critical for video playback performance. I hope it will be
> solved in the next version of N800 firmware too. But it we get some patch to
> solve this problem for testing earlir, that would be nice too.

The only patch is optimising that function, really.  Even if we did work
out a way to make Hailstorm happy, you can still only scale at those
exact multiples, which doesn't make it a viable general solution.

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