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ImageMagick DPX files and OpenGL Pixel Buffer Objects

I keep OpenGL Pixel Buffer Objects on because for the most part it makes using stacks much faster. For some reason, though, when I include DPX files created with ImageMagick (6.7.4-0 according to the metadata, DPX v2) in a Stack, using OpenGL Pixel Buffer Objects slows to an incredible crawl. GPU memory doesn't go nuts, but I get around 1.2 FPS (2K files). Turning off OpenGL PBO gives me about 20fps. Any idea what's going on here?

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    Alan Trombla

    Hi Dennis,

    It's unfortunately pretty impossible to tell in advance whether PBOs will help or hurt for a particular texel format on a particular card (although they much more often help than hurt).  In this case, it's likely that the texel format for the DPX is a bad fit for PBOs.  Can you include a screen grab of the ImageInfo widget for one of these DPX files ?

    Cheers,

    Alan

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    Dennis Serras

    I have to revise slightly. The problem comes when I combine one of the ImageMagick DPX files with a Nuke DPX with a composite mode. If I play them in sequence, they're fine, though RV freezes when switching between them momentarily. I've attached the two ImageInfos.

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    Dennis Serras

    PS Thanks, Alan!

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    Dennis Serras

    OK, checked on my Mac version, which is 3.12.15 on a 2011 MBP, and I do NOT have this problem. I have the problem on my Windows 64bit PC with dual NVidia boards (Quadro 2000 & Quadro 600) which has 3.12.12. So I don't know if its fixed on Mac or newer version.

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    Alan Trombla

    Hi Dennis,

    Thanks for the Image Info screen shots, I don't see anything there that might cause the problem you're seeing.

    BTW, the momentary freeze you mention is because the files are different resolutions and hence need different size PBOs.  There's a small hiccup when the new PBO is allocated and for files this big it's big enough to notice in playback.

    I'd recommend trying with the latest version (3.12.16 available from our downloads page) before we dig too deeply into it.

    Cheers,

    Alan

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