[directfb-dev] Re: Seeing "tearing" using mplayer dfbmga

[Denis Oliver Kropp <dok@directfb.org>]

Quoting Antonino Daplas (adaplas@pol.net):
> Some possibilites that can be considered:  
> 
> 1.  Direct rendering implies writing to the video memory directly, which
> is not just slow, but can be cached. In some hardware, you actually need
> to do a read of the video memory (even just one byte, just to flush the
> contents) to ensure that everything is in sync.  Especially true with
> MTRR.  MTRR accumulates all those little writes and after a certain
> threshhold, burst write everything at once.

Writing to the video memory is even faster than writing to system
memory on my P3 800 system with a G400 AGP. However, reading from video
takes ten times as long as reading from system memory.
Also I don't think that caching is the cause as the amount of data is
fairly big.

> 4.  Which is why we really need an AGP surface in DirectFB for things
> like video :)

Yes, we really need that, but I'm too lazy to refactor the surface manager
stuff for such an extension.

-- 
Best regards,
  Denis Oliver Kropp

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