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



Quoting Ville Syrj?l? (syrjala@sci.fi):
> On Mon, Dec 09, 2002 at 02:58:42PM +0100, Denis Oliver Kropp wrote:
> > The following only applies to the specified circumstances:
> > If you specify DSLF_READ you will lock the system memory instance, but
> > write only goes into video memory directly (surfaces.c: 490). And after
> > writing to video memory you never will get the system instance again.
> 
> Yes I noticed :) I was messing about with the locking stuff and was
> wondering why on some occasions things were hideosly slow. After I found
> the reason in the surface code things were much better. But what I still
> don't understand that even when mplayer claims that it will only write to
> the surface I really must use DSLF_READ or the performance will drop.
> Apparently it's better to copy the frame in one big chunk rather than
> decode it directly to video memory.

You can create a system only surface and blit from that, it will save a
hw blit after copying the data to video memory as it then already is written
to right location by the CPU.

> > > Perhaps we should just let the programmer worry about the signal and keep
> > > the DirectFB part very simple. So we just need a new DSFLIP_ASYNCHRONOUS
> > > (from the calling process' pov) And possibly a new layer capability flag
> > > DLCAPS_ASYNCHRONOUS_FLIP or something like that.
> > 
> > What about DSFLIP_ONSYNC and DSFLIP_WAIT.
> > The old DSFLIP_WAITFORSYNC could be defined as DSFLIP_ONSYNC | DSFLIP_WAIT.
> > The only combination that wouldn't make sense is DSFLIP_WAIT without
> > DSFLIP_ONSYNC.
> 
> Could work. Do you think we should still have a new layer capability flag?

Yes, but maybe we should call it "defered" because that would be clear
from any point of view.

-- 
Best regards,
  Denis Oliver Kropp

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