Re: live video texture -> frame rate

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Orad Hi-Tec Systems (orad_u++at++netvision.net.il)
Wed, 23 Oct 1996 07:10:39 +0300


Meiner wrote:
>
> Hello,
>
> I'm trying to use live-video-textures within a performer-application. The
> video-signal
> comes from crystaleyes-cameras through the siriusboard into an ONYX with RE2.
>
> The video-texture-stuff bases upon the 'vidtotex.c'-example coming with the
> videolibrary
> for the sirius-board.
>
I don't think vidtotex from SGI runs realtime, but...

> Now, the problem is, that the framerate is going down to 20Hz when I'm using the
>
> videotextures. I'm getting the videosignal noninterlaced, so it should be
> possible to
> get a framerate of 50/60Hz.
>
> The bottleneck seems to be the GL's 'subtexload'. I found it very surprising
> that the frame
> rate stays the same, no matter if I grab 1024x1024 or 1024x512 pixels from the
> siriusboard.
>

Video textures in RE2 require *very* special care

1. Use 1024x256, even if you have PAL (yes, you loose the last 32=576/2-256 lines)
2. Use RGB5 internal texture format (PFTEX_RGB_5 in performer, GL_RGB5_EXT
     in OpenGL, TX_RGB_5 in IrisGL)
3. Make sure your video source, Sirius, *and* graphics (DG) are all in sync.
4. Make the subtexload the last GL command (after the drawing, before the next
     vertical sync)
5. If the time you issue the subtexload is later than 11 ms after the start of
     the frame, you can forget about real-time. (This is for PAL, NTSC is about 8.5 ms)
6. If NTSC, you'll have to get some late Sirius patch for 5.3, or use 6.2

> So if anybody has an idea, ...

Buy an iR.
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