renderer CALayer via CARenderer into CGLContext (off screen)
renderer CALayer via CARenderer into CGLContext (off screen)
- Subject: renderer CALayer via CARenderer into CGLContext (off screen)
- From: John Clayton <email@hidden>
- Date: Thu, 25 Dec 2008 23:58:31 +0100
Hi All,
I've got a question re: CARenderer and rendering. Its probably best
to express first what I want to achieve, and then what I'm doing to
try and get there - maybe someone has a better idea and can point me
in the correct direction.
What I want to achieve:
- render each frame of a CALayer into a pixel buffer so I can feed
that into an quicktime ICM quicktime compression session
- the compression session requires CVPixelBuffer instances for each
frame
so, the approach I've so far taken is this: have the CALayer render
into a CGLContext by using the CARenderer class. I'm stuck here
though because I'm not sure where to go from here. I've rendered into
the context, but how do I get the image out of the context? I feel
I'm missing something - i.e. the connection between a context and the
actual image, for example: should I render into a texture or a pixel
buffer - in this case, pixel buffer feels like the right answer.
I reckon what I want to achieve is the following (correct me if I'm
wrong/crazy though):
1. create a pool of pixel buffer objects (lets say 5 for this example)
2. take a pixel buffer object from the pool and attach it to the
CGLContext
3. render a single frame using the CARenderer
4. feed the pixel buffer to ICM
5. goto (2) if there are still some available pixel buffer objects in
the pool
Or am I completely missing the point?
Thanks
--
John Clayton
Skype: johncclayton
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