Hello.
I am attempting to understand some performance behavior I am seeing in
my application. For starters my application :
1) uses display link for my main rendering timer
2) uses CVBufferRefs as input keys for images of type QCImage for
speed (to lessen any conversion over head) (I use this with quicktime
playback).
3) uses shared openGL contexts to display multiple views of my main
output (for preview windows, my app is a live video tool)
4) uses Quartz Composer patches with the Core Image Kernel language
patches for most of effects/compositing.
My understanding is that points 1 and 2 are best practices for
performance. Point 3 is necessary should I want to use my
CVOpenGLBuffer/texture to be displayed elsewhere (ie: another open gl
context/window/view), now, Point 4 is where my knowledge is somewhat
lacking.
I am seeing what is under my impression very poor framerates when
doing simple compositing between two QT movies. For example, mixing
two 24fps photo jpeg movies that are 854x480 pixels :
in my app : ~ 30fps
In QC Editor ~ 30fps
Within another environment, with the exact same CIKernel code (but
within a GLSL shader) I get a solid 60fps. (the environment being
Cycling 74's Jitter ).
However, if I enable the private uncorrectedCoreImage color option
within the QC editor, I can also get 60FPS.
My questions are,
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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