Reading 16-bit/channel ProRes with VTDecompressionSession?

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Created Jan ’22

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I want to modify my long-standing fully operational commercial VTDecompressionSession-based QT movie reader to read ProRes files to produce 16-bit/channel data. Requesting kCVPixelFormatType_64ARGB VTDecompressionSessionCreate just crashes internally. With kCVPixelFormatType_48RGB, VTDecompressionSessionDecodeFrameWithOutputHandler results in a -12905 error status.

What are working methods to decode this data? I need RGB data out; I'm not interested in re-creating a YUV decoder pathway. I see AVAssetReaderTrackOutput discussing reading ProRes, but that would require a separate path and it seems to be more limited --- I need random access to frames, which VTDecompressionSession isn't good at either but at least I've worked that out.

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MirrorMan OP

Jan ’22

There's an unacknowledged kCVPixelFormatType_64RGBALE pixel type --- little-endian 64-bit, which does work without errors in VTDecompressionSessionCreate and VTDecompressionSessionDecodeFrameWithOutputHandler. Even more surprising, there's a kCVPixelFormatType_64RGBAHalf that produces half-floats.

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