Pitch calculation method

Use the following formula to calculate the pitch. “OCT” is obtained from the table below, and “FNS” is obtained by substituting a value for “Fs”. “Fs” is the sampling frequency, for example 44.1 for 44.1KHz and 16 for 16KHz.

Calculation Formula


OCT value


Sampling frequency	5.5125KHz →	11.025KHz →	22.05KHz→	44.1KHz→	88.2KHz→
OCT value	-3	-2	−1	0	1

• For example, “OCT” and “FNS” when playing back samples sampled at 16 KHz are as follows. “OCT” is “-2” from the table, so “FNS” is 462 (1CEh).
  

  Therefore, the parameter “P7-P8: Pitch Word” for PCM stream playback is 71CEh.

6.4.6 Notes

Caution for continuous transfer
When transferring waveform data, avoid the long-term continuous transfer so that the sound CPU can operate. Note that this is given priority while the main system is accessing the sound memory, and the sound CPU cannot operate. If continuous transfer is required, divide it into transfer of about 1msec at the maximum. The sound CPU becomes operable by leaving a gap.

Notes on using DSP
When using DSP (effect) for PCM stream playback, mixer settings are required. When using DSP, prepare the necessary mixer data and issue the mixer setting command. Even if there is no sequence playback, the tone data for mixer settings is required.

  Remarks: One sample is the minimum unit data of PCM waveform data, and its size is the data width.
Depends on. It is 1 byte for 8 bits and 2 bytes for 16 bits. But
In the case of 4K samples, in the case of 8-bit PCM, it is 4096 bytes and 16 bits.
In case of PCM, it is 8192 bytes.