nesdev.com

I've spent some time over the last several days going over the VRC7 patch set with the CopyNES VRC7 tuner. This is about as close as I can get; some patches appear to be exact, but many have very minute differences which I could not reconcile. Also, there are many factors which make an exact match very hard; vibrato/tremolo don't synch with the note, so patches which use them are a bit variable, and there are some other random factors which seem to affect the onset of the note that I don't understand, but again they make some patches sound slightly different each time (just in the onset of the tone though).

This is an incremental improvement on the patch set quietust posted a few years ago. This would have taken a lot more time if it weren't for the prior work of kevtris and quietust, especially on the VRC7 tuner tool.



Hardware recording of patch comparison:
http://rainwarrior.ca/projects/nes/vrc7_rainwarrior_patch_test.flac
(Pairs of tones are built-in first, custom second, each at three pitches, when all patches are done, the entire test is repeated at low volume.)

The USB CopyNES host I used is available here:
https://github.com/bbbradsmith/usbcopynesblue

There are some minor source code changes to the VRC7 tuner tool; the modulator volume range is fixed (only went to 32 instead of 64), and saving files is fixed, as well as adding keyboard shortcuts Q/W/E to play the tones. I haven't uploaded a build with the fixed tool, but the source code fixes are in at that repository.


Edit: attached source code an NES/NSF for the test.

For anyone who is curious what the differences are, here's the changes in my new set, vs quietust's old one:

quietust.vrc7 > rainwarrior.vrc7:

patch 1:
Modulator output: 4 > 5
Modulator attack: 8 > 11
Modulator decay: 13 > 8
Carrier attack: 15 > 8
Carrier sustain: 1 > 2

patch 2:
Modulator output: 5 > 19
Feedback: 6 > 5
Modulator attack: 9 > 13
Modulator decay: 9 > 8
Carrier attack: 9 > 13
Modulator sustain: 6 > 2

patch 3:
Modulator output: 16 > 8
Feedback: 2 > 0
Modulator decay: 0 > 10
Carrier decay: 12 > 10
Modulator sustain: 3 > 2

patch 4:
Modulator rate scaling: 0 > 1
Modulator output: 29 > 24
Modulator attack: 9 > 7
Modulator decay: 15 > 8
Modulator sustain: 2 > 3

patch 6:
Carrier sustain: 9 > 15

patch 7:
Modulator output: 28 > 29

patch 8:
Modulator attack: 14 > 12
Carrier attack: 8 > 7
Carrier release: 5 > 7

patch 9:
Modulator sustain: 1 > 0
Modulator rate scaling: 0 > 1
Modulator output: 31 > 37
Modulator attack: 8 > 4
Modulator decay: 6 > 15
Carrier attack: 4 > 7
Modulator sustain: 2 > 0

patch 10:
Modulator output: 31 > 18
Modulator attack: 14 > 9
Modulator decay: 4 > 9
Modulator sustain: 1 > 4
Modulator release: 1 > 0
Carrier sustain: 1 > 0

patch 11:
Modulator level scale: 0 > 1
Modulator output: 43 > 41
Carrier level scale: 1 > 0
Feedback: 5 > 7
Modulator attack: 11 > 15
Modulator decay: 4 > 3
Carrier decay: 1 > 5
Modulator sustain: 2 > 10
Modulator release: 4 > 7
Carrier sustain: 15 > 1
Carrier release: 4 > 2

patch 12:
Modulator rate scaling: 0 > 1
Modulator output: 17 > 13
Modulator attack: 9 > 6
Carrier attack: 9 > 7
Carrier decay: 6 > 5
Modulator sustain: 1 > 2

patch 13:
Modulator attack: 8 > 10
Modulator decay: 2 > 3
Carrier attack: 10 > 9
Modulator sustain: 3 > 15
Modulator release: 1 > 7
Carrier release: 1 > 2

patch 14:
Modulator multiplier: 2 > 1
Carrier vibrato: 0 > 1
Carrier multiplier: 2 > 3
Modulator output: 13 > 12
Feedback: 2 > 0
Modulator attack: 12 > 9
Modulator decay: 3 > 4
Carrier attack: 7 > 10
Modulator sustain: 2 > 3
Carrier release: 5 > 6

patch 15:
Modulator output: 14 > 13
Modulator attack: 10 > 11
Modulator sustain: 4 > 5

I haven't compared side-by-side with actual recordings yet... but it sounds great to me at first listen!

Nice work. :)

Just realized I never published the ROM/NSF of the test, or its source code. Added to OP.

I found a few sustain, decay and release values are slightly off according to the waveforms in the patch test recording (internal patch first, approximated second). The set is very close, of course— I found only three instances one point off.

It was in the process of updating my emulator that I made the following adjustments to achieve close results to the h/w recording:

Patch #1:
Carrier decay 2 > 1
Carrier sustain 2 > 3
$"03 21 05 06 B8 81 42 37"

Patch #14:
Carrier release 6 > 7
$"61 63 0C 00 94 AF 34 07"

Patch #15:
Carrier release 7 > 8
$"21 62 0D 00 B1 A0 54 18"

(Also: thanks for your work, rainwarrior.)