[MPlayer-users] frame by frame play

[Ville Saari]

On Tue, Oct 12, 2004 at 10:09:46PM +0800, Jason Geng wrote:

> I am also interested in this. Where can I find more infomation about
> this patch?

I wrote such a patch about half a year ago and I also posted it here once
or twice. You can download it from:

    http://vs.iki.fi/mplayer/frameforward.patch

The patch is diffed against 1.0pre4, but I last used it on the CVS version
three weeks ago and it still applied fine, although with some offsets.

It only allows frame-stepping forward. If you hit the arrow keys while
mplayer is paused, it will advance to the next frame. Any other key will
unpause.

Frame-stepping backwards would be much more difficult to implement. This
patch is just a hack to set mplayer to automatically pause again after
it has played just one frame.

It may cause audio desync, because some audio drivers seem to be unable
to pause accurately and will actually overshoot some fraction of a second.
Normally the video will be played in fast-forward for a brief moment after
unpause to catch up, but if only one frame is played, the video can't
catch up and the audio advances further and further ahead each frame.
The end result might be tens of seconds of audio desync after final
unpause. Mplayer will compensate, but it looks quite funny.

But this only happens with some audio drivers. My Linux box has this
problem, but my PowerBook does not.

-- 
 Ville