On Thu, 22 Mar 2007 14:45:12 +0200
Jan Knutar <[EMAIL PROTECTED]> wrote:
> On Thursday 22 March 2007 09:21, Vesa Solonen wrote:
>
> > Have you thought about the problem of runtime synchronizing of
> > vertical refresh to video frame/field rate? DVB and other externally
> > timed streams would need this, to be playable at synchronous/coherent
> > frame rate (50 or 60 Hz). On local files the playback timebase might
> > be video card, so this is not necessary.
>
> I believe video players usually use the sound card as timing source,
> otherwise they'd have to compensate for the difference between the sound
> card's clock and system/graphics clock by resampling the sound.
That's MPlayers way of doing. VLC uses the stream as clock source
when available, if not it uses the system clock and of course, compensates
for the drift in the audio stream. I don't know how xine does it,
but i assume that it either syncs to the system clock/stream (the VLC way)
or syncs to the audio output device (the MPlayer way).
The issue of stream synchronus playback can be entirely
solved in software and does not need to be done in hardware.
Unless you need A-V sync below 0.5*frame-time, then you need
at least a little bit information from the graphics card, when
the current image drawing is finished, but any half decend card
supports this.
Attila Kinali
--
Praised are the Fountains of Shelieth, the silver harp of the waters,
But blest in my name forever this stream that stanched my thirst!
-- Deed of Morred
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