6.4.4 Stereo playback

PCM stream playback can be performed in stereo. Note that stereo playback uses twice as much memory as monaural as shown below. Since the buffer size specified by the playback start command parameter is the number of samples for one channel, prepare an area twice that actually.

6.4.5 Support for playback frequencies other than 44.1KHz

SCSP always plays back waveform data at a frequency of 44.1KHz, so if you want to play waveform data at other frequencies, use the pitch parameter. For example, when playing back half of 22KHz, it will be played at twice the pitch as it is, so if you play back with half the playback pitch, it will play at the original pitch.

Since the pitch can be up to ± 8 octaves (OCT) and further divided into 1024 steps (FNS) in one octave, any frequency can be supported within this accuracy range. If the sampling frequency is known in advance, calculate the pitch (OCT and FNS values) in advance using the pitch calculation method in the next section. By giving this pitch as a parameter when playing a PCM stream, the frequency at the time of sampling can be reproduced as it is.