1、IM-ADPCM
2、MS-ADPCM
3. Pulse code modulation record
ADPCM stands for adaptive audio pulse coding.
The MSADPCM/IMADDPCM/PCM/PCM you mentioned are all recording coding formats. Waveform coding: the time domain signal is directly converted into digital coding, and the reconstructed speech waveform keeps the waveform shape of the original speech signal as much as possible. The basic principle of waveform coding is to sample analog speech at a certain rate on the time axis, and then quantize the amplitude samples hierarchically and express them with codes. Decoding is the opposite process, and the received digital sequence is decoded and filtered to restore to an analog signal. Generally, no adjustment is needed when recording.