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

[a40e8119bbddbe7b3d281db117f19b32@interlinx.bc.ca]

On Sun, Dec 08, 2002 at 02:29:32PM +0500, Antonino Daplas wrote:
> 

[ disclaimer: I am no expert at all on G400 hardware.  My statements
come solely from what I have learned from an expert or two ]

> So you are not waiting for anything in between field 1 and field 2?  

No.  Not as far as my tests show.

> 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.

From what I have been told, you can give the G400 a field interlaced
frame (a frame with both fields in it) and it will display the first
field, and then the second field, timed properly to the vsyncs.  I
don't see a need for the front-end to wait for a vsync between those
fields.  The video card does the work of making sure they are
displayed one after the other while the front-end goes on th prepare
the next field interlaced frame for the vsync that occurs after the
2nd field is displayed.

Please correct me if there is something wrong with what I am
understanding.

b.

-- 
Brian J. Murrell

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