Contents

kVTDecompressionPropertyKey_AllowBitstreamToChangeFrameDimensions

A Boolean value that indicates whether a decoder is allowed to output buffers matching reduced frame dimensions in the bitstream rather than under-filling them.

Declaration

let kVTDecompressionPropertyKey_AllowBitstreamToChangeFrameDimensions: CFString

Discussion

This is an optional property only supported by video decoders for bitstream formats that have a provision for specifying output dimensions per-frame, such as AV1.

If a decoder doesn’t support this property or if the property value is set to kCFBooleanFalse, all decoded frames have the same dimensions as specified in the format description. In this case, if the bitstream changes the frame dimensions, the output buffer is padded to the dimensions specified in the format description.

When this property is set to kCFBooleanTrue, the decoder sets the dimensions of each output buffer to match the dimensions specified in the bitstream for that frame.

In all cases, output buffer dimensions will never exceed the dimensions specified in the format description.

In apps linked to SDK versions before this property was added, the AV1 decoder will behave as if this property is set to kCFBooleanFalse. Otherwise, value of this property defaults to kCFBooleanTrue where supported.

See Also

Decoder Behavior