[Mplayer-users] Re: new things in CVS
steve at daviesfam.org
Tue Jun 5 18:13:59 CEST 2001
> send _now_ your feature requests (here, to the list, for discussion)!
My request is about VSYNC-synchronization on the video output - for xv
output at least.
I may be being hopeful - I know that this is something that is only just
now coming in X itself...
Here's the background:
I'm using mplayer for the display side of my "media box" project.
I'm using the CVS version of mp1e for recording, using V4L2 (thanks to
pointers on this list).
My output will generally be to PAL Video - for now I'm using a Voodoo3
video output; later I might use some other card if I can find one which
support XVideo and interlaced output and low enough clocks for PAL video
rates - then I'll use a VGA->RGB SCART cable that I've made; this should
be better quality than the bt869 chip on the Voodoo3.
One common factor in this is my phyiscal display refresh must be 25Hz
(well - in two interlaced fields, of course). This is a requirement for
TV output. The captured video frame rate is 25Hz too - it was recorded
off broadcast television.
I'm getting really good results so far - but one thing I observe is that
mplayer's frame display is not locked to the screen refresh. Or, to put
it another way, mplayer doesn't wait till the vsync period before flipping
frames. There are two results:
- a picture "tear" is visible on faster moving sections where video
window is updated as the physical frame was displaying to the screen.
- a slight jerkiness is visible - especially on pans - caused I suggest
by the fact that some frames of the video are displayed more or less
than one exact display refresh - the result is a "jitter".
Now this issue is more or an issue for my application as my display
refresh rate is the same as my video frame rate. For output to a computer
monitor where your display refresh is much higher than your video frame
rate, the jitter will be much less noticable. Still, I want my media box
to be as good as possible so I'll try to work on this anyway.
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