Questions regarding SNES sound system

[tomaitheous]

Well, at the very least you should be able to do FM modulation with two sine waves. You could change the volume of the modulator to change the depth. I'm not very familiar with FM synthesis so I don't know what all it can do. I guess the general (complete?) lack of SNES games with FM synthesis means this isn't that viable.

2 operators allows for poor sounds like for example Adlib can do... 4ops is much more fun and with some effort you can get really nice sounding instruments. Most instruments I've made sound almost like my Yamaha's MIDI. Best part is that each instrument is less than 32bytes.

Except Adlib uses a sterilely produced sound tone for the carriar and operator. The SNES DSP is already using a very complex waveform. More complex than what even 4 operators can deliver form FM synths. It would akin to having one channel's final output of the 2612 modulate another channel entirely. But the DSP is already working with complex waveforms, so I don't see a real need for this. Stuff like vibrato/LFO and sweeps can be handle SPC700 processor.

[johannesmutlu]

for what i do know the genesis has actualy 10 soundchannels whereass 4 were originaly intended for sms games but they can do all work simonteniousely in md modes.
channel 6 can can do 8bit pcm samples i guess at 54 khz.
the snes has 8 digital soundchannels,those samples are in 4bit brr format,but those samples are decoded,reconstructed into 16bit 32khz,will the guessian filter does remove annoying noise but sadly also futher reduces the quality,the annalogue lowpass filter gives a nice mega bass sound and remove extra noise but also sadly eliminate even more hich freq,s,will the 4bit samples are upsampled to 16bit to compensate degradation,you will end up with a somewhat flatty,muffed sound,trough voices sounds can be fairly okey but sometomes
voices sounds more like they were recorded behind bars/dours,even then they can be still scratchy or noisy if the recording was bad done.
but the best advantage of the snes chip is, it can also stream 100% true 16bit 32khz samples toobad a 3 minute audio track takes up more space then even the largest snes game.

[tomaitheous]

but the best advantage of the snes chip is, it can also stream 100% true 16bit 32khz samples toobad a 3 minute audio track takes up more space then even the largest snes game.

That's not the best advantage.

The advantage of the SNES sound setup is that it's not strictly limited to specific set of instrument sounds like a game system FM chip. It can have a huge range of sound; soft or muffled ... or not. And it can do complex 4 note chords via a single channel. That's the strengths and "best advantage" of sample based synth - with the SNES audio.


Also, if you're talking about the Genesis channel 6 DAC, you're not gonna get 54khz PCM playback. The chip busy/wait flag. You can't just simply brute write to the DAC and expect whatever frequency you hard coded the z80 to. You'll miss sample updates/writes. TmEE leaves it at a reasonable 20-26khz and does double writes to ensure he doesn't get a missed sample update.

[tepples]

The advantage of the SNES sound setup is that it's not strictly limited to specific set of instrument sounds like a game system FM chip. It can have a huge range of sound; soft or muffled ... or not.

At a substantial cost in ROM space, which was expensive in the Super NES era. And at a mild cost in loading time; notice how much faster The Lord of the Rings switches between areas when music is turned off (not that it isn't still a piece of poo). One thing samples alone can't do is make a timbre that varies slowly over time, unlike the duty cycle of a pulse channel (think SID, not NES), the amplitude of an FM operator, or the resonant frequency of a TB303 bass.

And it can do complex 4 note chords via a single channel.

I've been able to coax fifth, fourth, major third, and minor third intervals out of TFM (tracker for Genesis's FM chip) by running the operators in a 2+2 configuration. Then I can do a 4-note chord on two channels. Doing this in samples would require a lot of sample RAM.

[mic_]

out of TFM (tracker for Genesis's FM chip) by running the operators in a 2+2 configuration. Then I can do a 4-note chord on two channels.

Only channels 3 and 6 allow this on the YM2612 (Genesis FM chip), since they're the only two channels that can be configured so that each operator has its own frequency setting.
Unless you're able to achieve all the desired frequencies of your chord with the MUL and DT parameters.

[tepples]

Unless you're able to achieve all the desired frequencies of your chord with the MUL and DT parameters.

This is the case. Choices for MUL pairs are 2 and 3 (fifth), 3 and 4 (fourth), 4 and 5 (major third), and 5 and 6 (minor third), and a quick perusal through Wikipedia's article on just intonation will help you figure out why these work. These are also the valid choices for pairs when doing intervals on Game Boy channel 3.

[TmEE]

Only channels 3 and 6 allow this on the YM2612 (Genesis FM chip), since they're the only two channels that can be configured so that each operator has its own frequency setting.
Unless you're able to achieve all the desired frequencies of your chord with the MUL and DT parameters.

Only channel3 has freq per operator setting, 6th does not.