ICM_COMPRESS_GET

ICM_COMPRESS_GET_FORMAT

The ICM_COMPRESS_GET_FORMAT message is sent to a video compression driver to obtain the output format of the compressed data.

Parameters

dwParam1: Specifies a pointer to a BITMAPINFO data structure indicating the input format.
dwParam2: Specifies zero or a pointer to a BITMAPINFO data structure used to return the output format.

Return Value

If dwParam2 is zero, the driver returns the size of the output format. If dwParam2 is not zero, the driver returns a status value (either ICERROR_OK or an error status).

Comments

If dwParam2 is zero, the driver should only return the size of the output format.

If dwParam2 is nonzero, the driver should fill the BITMAPINFO data structure with the default output format corresponding to the input format specified for dwParam1. If the compressor can produce several formats, the default format should be the one that preserves the greatest amount of information.

For example, the Microsoft Video Compressor can compress 16-bit data into either an 8-bit palettized compressed form or a 16-bit true-color compressed form. The 16-bit format more accurately represents the original data, and thus is returned for this message.