Inquiry: Using Pitch Modulation outside of SNES development?

[Norrin_Radd]

Hello, it's been a very long time since I posted here last, but after an exhausting search on the internet, I feel like I have to bow down to the masters of this stuff and humbly ask for help.

Note: TL;DR? Skip to "My Question"


My situation:

I write chiptunes and synth music, and recently I have been tasked with creating SNES music and sound effects for an upcoming project.


My philosophy on achieving this:

I want to take the aspects of SNES music I like, but apply my own song writing strategies to them. Sometimes this means I need to break or bend limitations, but always in the pursuit of the song writing. For me, the first snag in the song writing process and my creativity is shot. It makes it very hard to work for other people unless I can follow the path of least resistance. Because of this, I have historically preferred to use samples, and essentially gauge how closely I stay to the limitations in reference to how much it will completely kill my will to write. Whether or not that bothers people, I can't say I really worry about it any more (it used to bother me). I enjoy being able to go my own way just a little, but to balance it with having solid knowledge base of why the sounds are nostalgic or enjoyable in the first place. I never want to end up sounding like a youtube "8bit remix". You know the ones...


My dilemma:

While I have no issue ripping tagging and tuning SNES samples thanks to things like SPCTool. I had recently discovered that it also has a DSP Register Editor window which lets me actually research very key aspects of the sound. Such as the FIR settings and the actual value of the delay\ms.

However it was not until this very evening when I was ripping the sounds from Live A Live that I first noticed the Pitch Modulation check box being ticked, and hearing what it sounded like in the last track in the SPC called "Fall of the Demon King".

That sound... That amazing sound. This sound is used in all kinds of sound effects on the SNES, most notably for me is with the "Voice of Lavos" track from Chrono Trigger (and all throughout that game, really).


My question:

Is there a way to utilize this Pitch Modulation to create my own original sound effects using my own samples? Either in code, or rigging up something close. The ideal solution for me would be an application or even a VST that just applies SNES brand pitch modulation to a wav file exactly as easily as SPCTool can with that tick box, and spits out an effected wav file for use in things like Cubase or Modplug. Does anyone know of any such application tool or VST\processor?

And, if such a tool does not exist, can anyone tell me how this effect is achieved in technical terms, so that I might try to fabricate some signal chain of VSTs to process a sound in a similar way? Assuming such a thing is even remotely feasible.

I would love to hear my own voice ran through this hellish processor, as well as all sorts of tones. Something to tie the modern back in to the old.


Conclusion:

If you read this far, I appreciate your time. I am up so late that my eyes are stinging, but I wanted to get this question out there so that I would be able to sleep tonight, rather than lie awake wondering. If anyone has any info that could help me, it would be very much appreciate. Though, I must pre-warn you that my technical experience is deeply limited. I am good a fiddling with applications and song writing, but when it comes to the technical stuff, I am not only hopeless, but drastically out of time to be able to learn it all. Worst case scenario, I record some sounds and convert them to brr. But if I can get that Pitch Modulation going, that would be such a secret weapon of cool sound creation... I get so excited just wondering what stuff could sound like.

[kp64]

"Fall of the Demon King".
That sound... That amazing sound.

https://www.youtube.com/watch?v=MPciBloeOrc

I dont know anything about digital audio , so maybe this is technically impressive, but personally I don't consider this a pleasant sound.

[Norrin_Radd]

Context helps, I suppose. This is not the best use of Pitch Modulation, but the effect is basically an attempt at a demon screaming in defeat. I hear that sound and I wonder how it could be harnessed to create more tailored sounds, such as the Lavos scream, or even if it could be utilized musically for interesting sounds.

Consider that the sound you are hearing in Live A Live is mostly generated from a single channel plain square wave that quickly pitch slides up, holds, then slowly pitch slides down. The only difference is that Pitch Modulation is turned on. If you turn it off, all you hear is a square wave (I know this because SPCTool allows me to turn it off and hear what it sounds like without Pitch modulation). How you go from square wave, to a simulation of a demon screaming is very intriguing to me, and I wonder how else the sound could be done. What other instruments could be manipulated. What other sounds could be experimented with.

The best example of Pitch Modulation and what it can do would still be this, which is mostly made up of the very same choir samples used throughout the entire game, only with clever used of Pitch Modulation applied. If you get this from choir sounds, what the heck else might we find? I would love to find out.

https://www.youtube.com/watch?v=S_2KCMu5lj0

[lidnariq]

SNES Pitch modulation is a special limited form of ordinary frequency modulation. It's just that rather than modulating with a sine wave (as one usually thinks of FM), you can have an arbitrary (albeit BRR compressed) modulator.

Nocash describes the algorithm in his documentation, but it's a little bit cryptic. Have you ever played with Max/MSP or with PureData? Implementing this is a relatively simple patch.

If you look at the FFT of something that's been frequency-modulated by a sine wave, you get a Bessel function. More complex modulator → more complex frequency smearing.

[Norrin_Radd]

Is that all it is? Do you know if the BRR sample is the one actually modulating itself then? Since it's just a toggle on the SNES, I am curious as to what it means when you actually flick that toggle. Where does the modulator come from to modulate this carrier?

I did some preliminary searching on the internet, and to my surprise, I can't find a VST that allows you to modulate a wav using another wav. I guess because the result is usually pretty gnarled, but still, the potential to apply it as a vocal processor at the very least seems unbelievably tantalizing, and I can't believe it hasn't been done already. Unless of course it has. I will pester some of the forums on KVRAudio and see if anyone has any suggestions on that front.

As for the SNES front, thanks for the links and the suggestions. I am not sure I will be able to make sense of the SNES spec docs in order to construct any form of an accurate SNES Pitch Modulation. But I might just be able to hobble together something roughly similar using Pure Data. Though I have very little time to learn this tool, and implement these techniques, I'll give it my best shot, for now.

Edit for progress report:

I managed to rig up a solution to create new SNES sounds that sound all demented like that Chrono Trigger Lavos sound. Essentially, I load up SNESGSS and add my own SNES approved looped samples. Then create my sequence of pitch shifts up and down. Then I Export that file as an SPC file which I open in SPCTool where I can turn on Pitch Modulation and Noise. From there, I hit record in Cubase to record the output as I fiddle with the knobs and sliders of SPCTool to create some of the movement. At that point, I can attempt to splice the sounds into a usable sound effect from within Cubase.

This is not an ideal solution, but it is the closest I can come to being able to do what I want. This is my life...