I'll just keep talking to myself here. Perhaps I'll save someone from the same incredible frustration later.
Turns out that my problems with mangled and out-of-order frames can occur on all platforms and operating systems --- just because you have CVBufferRetain'd a buffer and then called CVPixelBufferLockBaseAddress on it doesn't mean that you own it or that nothing bad will happen to it. No, that would be too logical.... I just added a sleep into my code so that I hold on to the retained and locked buffer from a single frame (say frame 20) for a while before copying the data out of it. Meanwhile I continue to read the rest of the movie, then come back to read out the data from frame 20. Surprise! I get a completely different much later frame.
Further study of the headers in CoreVideo shows that there is a kCVPixelBufferPoolMaximumBufferAgeKey --- it seems that after a while, the buffer pool just assumes you're done with a frame and "takes it back" !!!!!!! I'm sure this sounded like a helpful feature to somebody late one night after a few beers, but this has absolutely no place in a complex multithreaded system. None. But it is on by default.
So, for the trick question of the day-----how can I get to the BufferPool setup to turn it off. Again, I'm working mainly from the QTPixelBufferVCTToCGImage sample. The CreatePixelBufferContext seems to be in the right area but I need to talk to the POOL creation and the value type is a bit dicey looking (perhaps a 0.0, not a CFNumber?)
Still waiting for someone to tell me why my callback can get called with no movie time at all, for some movies.
Russ
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