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



On Sun, 2002-12-08 at 09:08,
a40e8119bbddbe7b3d281db117f19b32@interlinx.bc.ca wrote:
> On Sun, Dec 08, 2002 at 03:59:12AM +0500, Antonino Daplas wrote:
> > If you're seeing half the rate, then the CPU is either too slow, you're
> > sleeping too long, or mpeg processing takes a lot of time.
> 
> 29.97 is not half the rate.  You have to consider that each vsync that
> I am counting is a full _frame_ (i.e. two fields) from MPlayer.  We
> are only interested in knowing about the vsync that occurs after the
> two fields in the frame have been displayed, thus the half-rate.
> 
So you are not waiting for anything in between field 1 and field 2?  
That will not provide a steady picture. If you're going to show video, a
metronome has to be provided, either by the frontend (mplayer, capture
card) or by the backend (TV out hardware syncing on TV signal, driver
waiting for vsync). Since you let mplayer give you interlaced data,
you're giving up the metronome of the frontend for in-between fields,
which presumes that the backend has to provide it.  Unless the matrox
hardware automatically sync-flips to your TV signal, then the only
recourse is to wait for vsync (or do it's own timestamping) in between
field 1 and field 2.  So, mplayer gives you data at 30 fps, you still
need to wait for vsync in between frames + in between fields at a total
of 60 fps.

Tony



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