S-DSP/Noise: Difference between revisions

Revision as of 00:33, 12 June 2023

Noise clock table

Hardware noise on the SNES is generated by a 15-bit linear feedback shift register. [1] Note that the noise sampling frequency is the perceived pitch (due to overtones) even though it is double (Nyquist) that of the fundamental.

Value	Sampling Frequency	Pitch
00	0 Hz	off
01	16 Hz	C0 - 38¢
02	21 Hz	E0 + 33¢
03	25 Hz	G0 + 35¢
04	31 Hz	B0 + 7¢
05	42 Hz	E1 + 33¢
06	50 Hz	G1 + 35¢
07	63 Hz	B1 + 35¢
08	83 Hz	E2 + 12¢
09	100 Hz	G2 + 35¢
0A	125 Hz	B2 + 21¢
0B	167 Hz	E3 + 23¢
0C	200 Hz	G3 + 35¢
0D	250 Hz	B3 + 21¢
0E	333 Hz	E4 + 18¢
0F	400 Hz	G4 + 35¢
10	500 Hz	B4 + 21¢
11	667 Hz	E5 + 20¢
12	800 Hz	G5 + 35¢
13	1.0 kHz	B5 + 21¢
14	1.3 kHz	E6 - 24¢
15	1.6 kHz	G6 + 35¢
16	2.0 kHz	B6 + 21¢
17	2.7 kHz	E7 + 41¢
18	3.2 kHz	G7 + 35¢
19	4.0 kHz	B7 + 21¢
1A	5.3 kHz	E8 + 9¢
1B	6.4 kHz	G8 + 35¢
1C	8.0 kHz	B8 + 21¢
1D	10.7 kHz	E9 + 25¢
1E	16 kHz	B9 + 21¢
1F	32 kHz	B10 + 21¢

References

@@ Line 1: / Line 1: @@
 Noise clock table
-Note that the noise sampling frequency is the perceived pitch (due to overtones) even though it is double (Nyquist) that of the fundamental.
+Hardware noise on the SNES is generated by a 15-bit [https://www.eetimes.com/tutorial-linear-feedback-shift-registers-lfsrs-part-1/ linear feedback shift register]. [1]  Note that the noise sampling frequency is the perceived pitch (due to overtones) even though it is double (Nyquist) that of the fundamental.
 {| class="wikitable"
@@ Line 74: / Line 74: @@
 === References ===
 * https://archive.org/details/SNESDevManual/book1/page/n174
+* [1] https://github.com/ares-emulator/ares/blob/master/ares/sfc/dsp/dsp.hpp#L76
 [[Category:Audio]]