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Re: 1 movie only on my ATI 9800?

On Nov 30, 2004, at 8:32 PM, Glenn Anderson wrote:

I am finding the opposite, decompressing 1920x1080 Photo JPEG QuickTime movies to a 32bit ARGB GWorld/texture is slightly faster than to a '2vuy' GWorld/texture on a single 1.8GHz 1st gen G5 with an FX 6800 GT.

How can YUV->RGB possibly be faster than no conversion at all? Even if you get the GPU to do an overlay the pixels have to come back to the CPU side prior to texturing.

Apple's Photo-Jpeg does have a 'lossless' mode that could be RGB, but I don't recall what color-space it uses. If you are using that, and it is RGB, then it will be faster to use ARGB. I don't think I've ever run across 'lossless' Jpeg though, so outside that specific case YUV will be much, much faster.

I suspect you will find the problem was the 32bit GWorld you were using was allocated by QuickDraw or QuickTime, so did not have a baseAddr aligned to 32 bytes and/or rowBytes that is a multiple of 32 bytes

I allocate my own buffer, and that buffer is also used in processing by the CPU. I've never seen ARGB pixel formats perform better than YUV for video sources.

glPixelStorei(GL_UNPACK_CLIENT_STORAGE, GL_TRUE) and glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_STORAGE_HINT_APPLE, GL_STORAGE_CACHED_APPLE) gives the best performance.

Yes, but there is a caveat with client_storage. If you do process the pixels after the QT decompression and before texturing, then client_storage can become a problem. QT and GL aren't synchronized in any way so it's quite possible and even very likely that artifacts will occur with client_storage enabled. Tasking QT after the texturing calls does help, but it's much more difficult to design a processing chain in that order, and in my case the render code was already in place. The problem gets worse the faster the processing code, which is pretty frustrating to see after writing a ton of blazing Altivec only to have to turn off a vital GL feature to prevent unpleasant visuals.

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References: 
 >Re: 1 movie only on my ATI 9800? (From: Lorenzo <email@hidden>)
 >Re: 1 movie only on my ATI 9800? (From: chris clepper <email@hidden>)
 >Re: 1 movie only on my ATI 9800? (From: Glenn Anderson <email@hidden>)



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