[MPlayer-users] per-frame seeking in AVI files

[Felix Buenemann]

On Wednesday, 6. February 2002 01:41, Lars Damerow wrote:
> | audio buffering is made at 3 places: demuxer, codec and soundcard.
> | we cannot control soundcard, cannot seek backward in demuxer and
> | depending on audio format, maybe we cannot control buffering of codec.
> | so it's near to impossible.
> |
> | for short term backward seek, we could perserve last N seconds of decoded
> | audio, keep resetting audio device and with some luck and well working
> | audio driver it may work...  anyway i don't know what is 40ms audio chunk
> | playback good for. you'll hear only ticks, no sound...
>
> For us, silent frame-stepping would be perfect. Single frame stepping
> really only make sense when the movie is paused, anyway.
>
> So how about this: if frame-stepping is only enabled when the sound is
> paused, the hack you described earlier would work just fine for our
> purposes, and once your TODO list is shortened, would work for backward
> steps as well. Then, once the movie is unpaused, MPlayer could seek the
> audio to the right place in the same way it would when the user had done a
> 10-second or 10-minute seek. Would that take care of the A-V syncing
> issues?

Just looking at hardware dvd standalones and stuuf, they always do single 
frame stepping without sound (and IMHO go into pause mode first, too).

So for MPlayer, how about this:
user goes into pause mode, this will switch behaviour to frame stepping and 
we disable audio while in pause/frame-stepping mode. We can simply change 
key-meanings in this mode from +/-10sec to +/-1frame and +/-1min to +/-1sec 
and page up/down to +/-10sec.
Now user wants to go on playing the movie normally, then we can simply 
reenable audio, do a seek to the next available keyframe and resync the audio.

Btw. it should be pretty easy to add an osd display state, which displays 
current frame instead of the osd timer.

Hmm and thinking 'bout pixar, a mentioning of MPlayer in the movie-credits 
would be cool ;)

-- 
Best Regards,
	Atmos
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