The UMSVideoDecoderMClass class is a metaclass that defines the class methods for children of the UMSVideoDecoder base class. In particular, UMSVideoDecoderMClass specifies creation methods for UMSVideoDecoder objects.
To learn more about the UMSVideoDecoderMClass class, see:
For introductory information, see MetaClass Objects.
To avoid name collision on defines, integer values have been captured as enumeration lists. The set of valid values from an enumerated list can vary with the application. The detailed method descriptions describe the valid or possible values for the specific use. The enumerated lists that are defined for this object are listed as follows:
enum ReturnCode { Success, Failure, FatalUMSError, NoConfigObject, AliasNotFound, PropertyNotFound, InvalidClassName, NotAChild, UnsupportedFormat, MemoryError };
This method returns an instantiated child of the UMSVideoDecoder class as determined by the from_format and to_format parameters. The particular child returned depends upon interaction with a UMSConfig object.
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For certain Error Codes, more specific information can be obtained from the error_string parameter.
The VideoDecoderMClass uses the configuration file to determine that subclass of the VideoDecoder class to instantiate. The make_by_transformation method first attempts to find an alias that matches the concatenation of TO and the to_alias parameter. If this is found, it checks the video_format_qualifier property of each clause until it finds one that matches the from_alias parameter. The CLASS_UMSVideoDecoder property indicates that particular VideoDecoder subclass to instantiate.
TORGB8Dither: video_format_qualifier "IBMUltimotion" CLASS_UMSVideoDecoder "UMSUMVideoDecoder" *NEXT: video_format_qualifier "IBMMotionJPEG" CLASS_UMSVideoDecoder "UMSJPEGVideoDecoder" *NEXT: video_format_qualifier "IBMRTV2" CLASS_UMSVideoDecoder "UMSRTV2VideoDecoder" *NEXT: video_format_qualifier "IBMRTV21" CLASS_UMSVideoDecoder "UMSIndeoVideoDecoder"
For introductory information, see MetaClass Objects.