DVI IMA ADPCM
According to the XAnim multimedia application, there are two variants of DVI IMA ADPCM, both of which are encoded and decoded with the IMA ADPCM algorithm. The original variant encodes the top nibble of a byte first, then the bottom nibble. The revised variant has the opposite encoding order.
[IMA ADPCM] and [Microsoft IMA ADPCM] are both the same codec, an implementation of the IMA/DVI ADPCM standard, the only difference being encapsulation around the ADPCM data. The [IMA ADPCM] standard did not specify RIFF/WAV file headers, while the [Microsoft IMA ADPCM] implementation does.