proper settings for spc -> mp3?

Just to clarify: The higher quality/frequency/bitrate settings in SNESAmp have nothing to do with upsampling, they affect the mixing process itself. Think of it as playing an old 3D game on the latest 3D hardware and thus being able to choose higher display resolutions, more and better AA etc. The textures (instrument samples) and the game scenes (music score) don't change, but some may like the improved processing.

However if you want to convert SPC files and want to claim it to sound like the real SNES you should pick the "like SNES" DSP setting, this disables all the additional flexibility that emulation can offer.

Jam it back in, in the dark.

Well, the author of SNESAmp is the same as the one for SNESAPU. The SNES' sound unit comprises of the SPC700 CPU and the DSP it controlls. The SPC700 by itself makes no sound but just executes the program in the SPC files. The DSP makes the sound and can be implemented in a more loose way, and that's how the mixing can be improved. SNESAmp has these features since I bugged the author to do so, such features can be implemented as long as mixing is done in some hardware (i.e. most gaming systems except N64, GBA and afaik PSP which do sound in software). There is no docs except this basic one: SNESamp > SNES sound module If you don't want to believe me you can look at the sources of SNESAmp/SNESAPU.

There's nowhere I can't reach.

No, no, no. You still didn't get it. Think of synthesizers/DSP units like MIDI alike units, the unit sending the music commands (SPC700 in the SNES case) doesn't have to know the mixing rate or process, it's completely irrelevant to sending any music commands. As long the emulated synthesizer/DSP hardware is able to interpret all incoming commands correctly the mixing is irrelevant and doesn't need to stick to the original spec, this is how SNESAPU can and does allow for higher quality settings, and this can be implemented in any emulation of hardware synthesizers. Abstraction allows for flexibility. The interfaces to synthesizers/sound DSPs are already abstracted by their very purpose, they are not every world CPUs needing one to stick to ticks and cycles to work.

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