When specifying ADPCM parameters in PlayIt_Open R5 is used to supply blocking information. This can just be the frames per block in which case PlayIt calculates the bytes per block (ie block alignment) from it.

From v1.59 bit 31 of R5 can be set in which case the remaining bits contains a pointer to a small table of two 32-bit words:

0 | frames per block
4 | bytes per block

PlayIt will only correctly calculate the bytes per block by itself if there are no wasted bits at the end of each block. This is mainly useful for Wave formats in which the two required parameters are specfied in the header eliminating any calculation requirements.

Note that when the auxiliary parameter is returned as information by various SWIs only the frames per block is returned and bit 31 is always clear.

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