Re: Regarding Quartz Composer vs Core Image vs GLSL

For the record, should others need/want to know, thanks to an off list email hint from Raphael Sebbe, I was able to narrow it to:

adding this code right after I called QTOpenGLTextureContextCreate for my QT movie playback.

// this turns off any weird colorspace conversions and thus extra overhead.

QTVisualContextSetAttribute(textureContext,kQTVisualContextWorkingColorSpaceKey, CGColorSpaceCreateWithName(kCGColorSpaceGenericRGBLinear));

QTVisualContextSetAttribute(textureContext,kQTVisualContextOutputColorSpaceKey, CGColorSpaceCreateWithName(kCGColorSpaceGenericRGBLinear));

All of my QCRenderers also now use kCGColorSpaceGenericRGBLinear as well, and I am seeing much better frame rates, very close to QC editor and Jitter. Thanks, and hope this is helpful to others.

Im still not 100% convinced this is an ideal solution (or, in fact, what the QC Editor is doing), but that is mostly because my understanding is far from complete.

Ill investigate further, and hope list recipients do not mind the monologue. Thank you,

On May 21, 2008, at 11:20 PM, vade wrote:

1) how can I procedurally disable color correction for Core Image within my App? I see nothing obvious in the developer documentation for this, but could be missing something conceptually... or just have missed it :)

2) is there meaningful overhead by using a Quartz Composer patch with a CIKernel patch in it, rather than biting the bullet and compiling my CIKernels as Core Image Units and loading them / using them are Core Image units natively? (IE, skip the whole QC patch step, just load a CIUnit and use it?)

3) should I be expecting similar performance with Core Image for video processing as I get with GLSL shaders?

I appreciate any insight, Im a bit confused and disappointed by my apps performance, especially when trying to follow the best practices and not seeing any real boost.

Thanks in advance,
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References:
	>Regarding Quartz Composer vs Core Image vs GLSL - a performance question (From: vade <email@hidden>)

Re: Regarding Quartz Composer vs Core Image vs GLSL - a performance question