78 lines
3.7 KiB
Markdown
78 lines
3.7 KiB
Markdown
# Super Nintendo Entertainment System (SNES)/Super Famicom
|
|
|
|
the successor to NES to compete with Genesis, packing superior graphics and sample-based audio.
|
|
|
|
its audio system, developed by Sony, features a DSP chip, SPC700 CPU and 64KB of dedicated SRAM used by both.
|
|
this whole system itself is pretty much a separate computer that the main CPU needs to upload its program and samples to.
|
|
|
|
Furnace communicates with the DSP directly and provides a full 64KB of memory. this memory might be reduced excessively on ROM export to make up for playback engine and pattern data. you can go to window > statistics to see how much memory your samples are using.
|
|
|
|
some notable features of the DSP are:
|
|
- pitch modulation, meaning that you can use 2 channels to make a basic FM synth without eating up too much memory.
|
|
- a built in noise generator, useful for hi-hats, cymbals, rides, effects, among other things.
|
|
- per-channel echo, which unfortunately eats up a lot of memory but can be used to save channels in songs.
|
|
- an 8-tap FIR filter for the echo, which is basically a procedural low-pass filter that you can edit however you want.
|
|
- sample loop, but the loop points have to be multiples of 16.
|
|
- left/right channel invert for surround sound.
|
|
- ADSR and gain envelope modes.
|
|
- 7-bit volume per channel.
|
|
- sample interpolation, which is basically a low-pass filter that gets affected by the pitch of the channel.
|
|
|
|
Furnace also allows the SNES to use wavetables (and the wavetable synthesizer) in order to create more 'animated' sounds, using less memory than regular samples. this however is not a hardware feature, and might be difficult to implement on real hardware.
|
|
|
|
# effects
|
|
|
|
- `10xx`: set waveform.
|
|
- `11xx`: toggle noise mode.
|
|
- `12xx`: toggle echo on this channel.
|
|
- `13xx`: toggle pitch modulation.
|
|
- `14xy`: toggle inverting the left or right channels (x: left, y: right).
|
|
- `15xx`: set envelope mode.
|
|
- 0: ADSR.
|
|
- 1: gain (direct).
|
|
- 2: linear decrement.
|
|
- 3: exponential decrement.
|
|
- 4: linear increment.
|
|
- 5: bent line (inverse log) increment.
|
|
- `16xx`: set gain (00 to 7F if direct, 00 to 1F otherwise).
|
|
- `18xx`: enable echo buffer.
|
|
- `19xx`: set echo delay
|
|
- goes from 0 to F.
|
|
- `1Axx`: set left echo channel volume.
|
|
- this is a signed number.
|
|
- 00 to 7F for 0 to 127.
|
|
- 80 to FF for -128 to -1.
|
|
- setting this to -128 is not recommended as it may cause echo output to overflow and therefore click.
|
|
- `1Bxx`: set right echo channel volume.
|
|
- this is a signed number.
|
|
- 00 to 7F for 0 to 127.
|
|
- 80 to FF for -128 to -1.
|
|
- setting this to -128 is not recommended as it may cause echo output to overflow and therefore click.
|
|
- `1Cxx`: set echo feedback.
|
|
- this is a signed number.
|
|
- 00 to 7F for 0 to 127.
|
|
- 80 to FF for -128 to -1.
|
|
- setting this to -128 is not recommended as it may cause echo output to overflow and therefore click.
|
|
- `1Dxx`: set noise generator frequency (00 to 1F).
|
|
- `20xx`: set attack (0 to F).
|
|
- only in ADSR envelope mode.
|
|
- `21xx`: set decay (0 to 7).
|
|
- only in ADSR envelope mode.
|
|
- `22xx`: set sustain (0 to 7).
|
|
- only in ADSR envelope mode.
|
|
- `23xx`: set release (00 to 1F).
|
|
- only in ADSR envelope mode.
|
|
- `30xx`: set echo filter coefficient 0.
|
|
- `31xx`: set echo filter coefficient 1.
|
|
- `32xx`: set echo filter coefficient 2.
|
|
- `33xx`: set echo filter coefficient 3.
|
|
- `34xx`: set echo filter coefficient 4.
|
|
- `35xx`: set echo filter coefficient 5.
|
|
- `36xx`: set echo filter coefficient 6.
|
|
- `37xx`: set echo filter coefficient 7.
|
|
- all of these are signed numbers.
|
|
- 00 to 7F for 0 to 127.
|
|
- 80 to FF for -128 to -1.
|
|
- make sure the sum of these is between -128 or 127.
|
|
- failure to comply may result in overflow and therefore clicking.
|