[Theora-dev] Theora camera/fast computers
giles at xiph.org
Tue Mar 22 17:39:05 PST 2005
On Tue, Mar 22, 2005 at 05:14:39PM -0700, Andrey Filippov wrote:
> What exactly effects did you notice about the noise? Maybe there are some
The noise level (including the chroma subsampling artifacts) is pretty
high, but doesn't change between frames in the static parts of the
scene. That, the resolution, and watching it at 7 fps, gives it a really
interesting 'frozen in time' feeling.
> This will come. Currently when there is no restriction to the frame rate
> placed (in a web interface when the frame rate input field is blank or 0)
> systems tries to run sensor as fast as possible. With the default sensor
> clock of 48MHz and required "margins" around the used window of
> (1280+4)*(1024+4) it all results to that frame rate. It is possible to
> program the sensor clock and also change "virtual frame" of the sensor by
> adding invisible rows and/or columns.
So it just works out that way? Interesting. How fast can the sensor go?
And can you bin the pixels to read out the full frame at lower
> What about dual-CPU systems? Is it possible to load them properly? What
> about Intel - do they have any advantages? I'm trying to build a demo
> system that could handle the stream even if it will be rather expensive -
> I don't think I have much choice here.
Well, that's not existing software. IF you bought a dual 3 GHz Xeon, AND
Ruik gets a good speedup with the idct, AND some simple paralellization
scheme works, THEN you might hit 30 fps by mid April. I guess you'll get
to find out!
I'd experiment with paralellization first to see what scales the best.
Off the top of my head you could try: serial stream decode but parallel
frame reconstruction (best for smp) or entirely parallel decode dropping
anything outside the crop (might work on a cluster of mac minis).
> I'm trying to be able to demonstrate the camera at it's best :-). BTW, I
> made a clip of the falling water droplets on a narrow frame of 1280x64
> pixels at 360fps.
Cool! Put that one online. :)
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