I've encountered more wiggliness from QuickTime. As mentioned, I am feeding SetMovieTime only the "interesting times" retrieved from the movie. But my QTVisualContextImageAvailableCallback is receiving DIFFERENT times for the frames. For example, 201 is the exact 'interesting time' but the image comes labeled as 200. So I put in a wiggle-room factor of +/-1 --- and that lets it read a fair number of movies.
But, I've discovered movies that fail immediately on the first frame. In one example, the interesting times are
0, 3, 23, 43, 63, ... --- the step between frames is nominally 20 with a timescale of 600, ie 30 fps
When my reader goes to read the frame 0, it does a SetMovieTime of 0 --- but the image callback occurs with a value of -17 !!! That is the time the frame would have had if it was evenly spaced relative the others, ie 3 - 20 = -17.
Reviewing the GetMovieNextInterestingTime documentation and sample code, it seems designed for timevalues >=0. But what I'm seeing makes me think maybe the first frame in a movie can have a negative timevalue, but it isn't being detected/reported right by GetMovieNextInterestingTime?
This is all very puzzling. I continue to expect to be able to read out exact timestamps from the movie using GetMovieNextInterestingTime, be able to feed them to SetMovieTime, and have those same exact timestamps be reported in the callback.
Russ
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