- ADPCM playback notes Each ADPCM format maxes out at just under a specific limit. If you attempt to play at the limit or faster, the decoded audio exhibits jitter/artifact noise as if the DSP has signalled an output rate faster than it decode. Note that the maximum discovered is almost DOUBLE in some cases the maximum listed in Creative's official documentation. 4-bit ADPCM: Maximum just under 16KHz 2.6-bit ADPCM: Maximum just under 16KHz 2-bit ADPCM: Maximum just under 19KHz