The ACB file means Atom CueSheet Binary file.
Multiple waveform data are encoded in the format that can be played back with CRI Atom library, added playback parameters to them, and packed into a single file.
File Structure
ACB file contains the following data elements:
Cue information (Sound is played back by specifying the Cue.)
The more Cues are contained in ACB file, the more memory is needed for data loading.
In this case, separate it into small ACB files, and change the CueSheet when using it.