Thanks, but from what I've seen, this approach is heavily oriented towards vanilla consumer TV-playback applications. QTVisualContextCopyImageForTime is quite specific that only a limited range of frames can be passed in, with no backwards travel. That makes it useless for me----I need (procedural non-event-driven) random access on demand---it's OK to be a bit more efficient for frame-by-frame forward playback, but random frame access is required for pro applications. With an intra-frame codec like ProRes, there should be very little penalty for random access above the disk access time.
Le 14 juin 08 à 19:44, Russ a écrit :
> My app retrieves the decompressed images from QT movies as fast as
> possible (>realtime), and I have long-standing working code using
> GetMoviePict and QDPictDrawToCGContext. However, performance is poor
> and when I look at it with Shark it is clear why --- the codec is
> only a small portion of the time per frame....
>
> Is there a more efficient access path? Ideally I'd want to be able
> to supply recycled storage for the codec to render the image into
> directly....
This sample code may give you some starting points about the modern
way to extract image from a Movie:
http://developer.apple.com/samplecode/QTPixelBufferVCToCGImage/listing1.html
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