BRR looping and sample directory

[psycopathicteen]

Say I want to have 2 instrument samples, a square and a triangle wave.

Is this currect?

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directory:
dw square
dw square
dw triangle
dw triangle

square:
db $00,$00,$00,$00,$00,$00,$00,$00,$00
db $02,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff

triangle:
db $00,$01,$23,$45,$67,$89,$ab,$cd,$ef
db $02,$fe,$dc,$ba,$98,$76,$54,$32,$10

I am hearing sounds, but neither sound like a square nor a triangle, and one has a different pitch than the other.

Am I messing this up anywhere?

[ccovell]

I know next to nothing about BRR, but isn't SNES sample data 16-bit?

[psycopathicteen]

Found my mistake.

"range" bits had to not be 0, and the "end" bit had to be set on the last sample chunk.

[mic_]

This is what I use (I got it from Memblers' NSF player):

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; 50% square
.DB $b3,$88,$88,$88,$88,$77,$77,$77,$77

And if you want it with twice the period:

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.DB $b2,$88,$88,$88,$88,$88,$88,$88,$88,$b3,$77,$77,$77,$77,$77,$77,$77,$77

and so on.

isn't SNES sample data 16-bit?

It's 4-bit.

[psycopathicteen]

Another question. I heard from many places that the SNES uses interpolation on the samples.

1) what kind of interpolation is it, and how is it calculated?

2) does it use interpolation on octaves higher than the sampled frequency?

[tepples]

I heard from many places that the SNES uses interpolation on the samples.

1) what kind of interpolation is it, and how is it calculated?

It's some sort of 4-tap "Gaussian interpolation", and it's calculated the way the bsnes source code says it's calculated. I still haven't been able to get someone to explain the precise difference between "Gaussian interpolation" and standard 4-tap cubic spline interpolation.

[psycopathicteen]

Here is another question. Is the Gaussian filter always the same, or does it vary depending on what note the channel is playing.

[Bregalad]

I admit the "guassian interpolation" is something I've yet to really understand.
However, I'm pretty sure it does some kind of anti-aliasing when downsampling (playing the sample at a higher rate than it's original rate, that is higher than 0x1000 in the freq regs), so that parasite low frequencies doesn't appear.