[Kdenlive-devel] moved here from kde-multimedia (was Re: Multimedia Frameworks)

[Christian Berger]

Am Freitag, 25. Oktober 2002 23:05 schrieben Sie:
> On Friday 25 Oct 2002 9:28 pm, Christian Berger wrote:
> > Am Freitag, 25. Oktober 2002 21:21 schrieben Sie:
> > > The realisation that I have had recently is that if you are going to
> > > make a preview, you might as well ask the cutter to do it. If you
> > > don't, then you have to effectively duplicate a cutter within the
> > > GUI, and you will also have a great amount of inconsistancy between
> > > what the preview is and what the final output will be.
> >
> > True, but generating a preview frame takes a lot of time anyhow, so
> > the overhead of moving it around is minimal.
>
> Not necessarily. If you have a video card that can perform realtime
> transitions and effects (for instance, the Matrox RT2500) then throwing
> the preview from one part of memory to another will be an unacceptable
> drag on performance.

Well first of all supporting such cards will take quite a long time, and 
second, we could still make somekind of parameter telling the cutter where 
to overlay the image. Maybe the cutter could tell the GUI wether it's able 
to "grab" an image, "overlay" an image to a certain area on the computer's 
screen, or "display" an image on another monitor (like a VCR)

> Another point I can draw from the Matrox card example is that some
> hardware can draw to the screen in hardware, and "overlay" the video
> window on top of video output of the computer. The only place where we
> know the optimal way to display video onscreen is from within the
> (potentially hardware accelerated) cutter.

I once had an MPEG card working like that (yes a special card just for 
MPEG1, worked quite well on my 486). Well that's my idea from above, the 
cutter should then tell the GUI what it can do and how much cost is 
involved. For example if you have a timeline with thumbnails, the only way 
of doing this is the "grab" function. A VCR for example might be able to 
grab a frame, but verry high costs are involved. If a card features 
overlay it might have verry low costs associated with it.

I personaly doubt moving an image around in memory is _THAT_ consuming. 
Just think of that Sinclair guy, he moved images around on a Z80 50 times 
per second.

> Cheers,
> Jason

Servus 
  Casandro

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