nesdev.org

I tried installing "Microsoft Visual Basic 6.0 Common Controls" from MS support site (searched for the error on the net) but that didn't fix it.

OK maybe my second method didn't work because I explained it backwards (I can't say how much hate when you have 1/2 chances of saying something wrong - I always end up saying the wrong thing no matter how much I think about it). When the pitch is decreasing, and the period increasing, you're doing ...

OK it might be stupid for me to ask it this way but did you try both techniques I mentioned ? At least of them should somewhat work I guess :roll: At worse, I think the frequency for a A note on a particular octave is $fd. Maybe you could fine-tune everything a bit up, so that it is something aroun...

Well I guess the test program I did isn't the best implementation of how to write the two period registers. In my actual audio engine it's just a pair of lda/sta instructions; lda periodLo sta $400a lda periodHi sta $400b which could easily be changed to; lda periodLo ldx periodHi sta $400a stx $400...

Writing dummy values doesn't seem to improve it at all, if anything it's worse. However I tried the switching-the-order-depending-on-direction idea like this; triVib: ldx toneIndex lda toneHi,x sec sbc oldHi beq @c bmi @down lda toneHi,x sta $400B sta oldHi @c: lda toneLo,x cmp oldLo beq @next sta $...

You mean why the waveform in your screenshot appears to jump back a few phase steps, rather than forward by a few as one would expect? No idea on that. Or perhaps why it occurs at different rates on different emulators? Granularity of them running their emulated APU, or possibly different initial t...

Damn! I think he's got it.

There's still an elephant in the room though.

At least on Windows, Nestopia appears to reset the phase or the DC-killer or both when emulation pauses and restarts. Sometimes a momentary pause occurs a few seconds after a ROM starts. Yep, I'm aware of that one (I think I posted a great big thread about it last year before someone mentioned the ...

Full code, ASM6 format; ;-------------------------------------------------------------------------------- ; iNES header ;-------------------------------------------------------------------------------- ; iNES identifier .BYTE "NES",$1a .BYTE $01 .BYTE $00 .BYTE %00000000, %00000000 .BYTE $...

And it gets even stranger. I thought the simplest way to test this would be to knock up a quick ROM that just does nothing but modulate the period of the triangle voice around period $0100. So I'm doing this in the NMI; triVib: lda #$81 sta $4008 lda #$00 sta $4009 ;vibrato speed = advance through t...

...it happens on the NES too.

I'm now officially freaking out. :S

What happens on a NES? Not had chance to try it yet. However, I started to suspect it was my Vibrato routine as it is a bit strange (table-based using a fractional pitch table) so I simulated Vibrato with an FX Table using my Sxx command (just adds a signed 8-bit value to the pitch every frame) lik...

Hmmmm. Scratch that : it does happen in FCEUX just infrequently.

You're probably writing a zero period to the triangle momentarily, so that it very quickly advances to a different phase, then writing some other period. That's the only way to change its phase like this, aside from an emulator bug. I first made sure that the zero period thing wasn't happening by d...

I can only test this in Nestopia (Mac) at the moment because of the fact that the ROM needs 32K SRAM support but I thought I'd see if anyone would care to speculate. I get this strange random clicking/popping coming from the triangle channel but only on a certain note and only when I'm doing vibrato...