Hello list,
I'm having a hard time writing movie files.
What I'm doing;
I'm getting uncompressed YUV 422 frames from an IIDC camera through the Sequence Grabber / SGDataProc.
The Sequence Grabber is configured for record mode, with preview of frames and writing to file disabled (since I'll be doing that)
- SGSetChannelUsage set to seqGrabRecord but not seqGrabPlayDuringRecord
- SGSetDataRef is set up with a dummy dataref and with seqGrabDontMakeMovie
I'm sending all frames from the SGDataProc to an ICM decompression session, previewing them through Core Image, compressing them through an ICM compression session.
At last, writing them to a new movie file <<<< here's the problem!
Here's how I'm doing the writing:
- creating a new dataref with QTNewDataReferenceFromFullPathCFString
- creating the movie with CreateMovieStorage
- setting up the video track and media (NewMovieTrack and NewTrackMedia with VideoMediaType... BeginMediaEdits)
- adding the samples with AddMediaSample2, all needed information like the ImageDescription and sample duration are comming from the ICMEncodedFrameRef (I'm letting the ICM compression session compute the sample durations)
All of the above is working, but AddMediaSample2 fails as soon as the file reaches 2 GB if capturing over an AFP share - when using the sequence grabber to write the file there is not such a limitation.
Also, when using the sequence grabber to write uncompressed (YUV422) samples, activity monitor reports as much as 40MB/s throughput. When using my custom writer, throughput never gets above 20MB/s - what is actually limiting my frame rate.
I really dont know what Im doing wrong: what is the Sequence Grabber doing differently?
Regards, Mark
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