General purpose PCM channel idea

[Weeppiko]

Currently the only way to play PCM data on TIC-80 it's through the Sound Registers, but the sound suffers a lot from this, since it is only able to play up to 1920hz and there is only 4 bits of depth, and on top of that there is also the fact that some flat lines are threated as noise, which makes it even worse to deal with. There was a mention about being able to poke to the sound registers during SCN to help with that but this was never really addressed.

So, I was thinking about how else it could be done, and the idea was to have only a small buffer in RAM (no pitch control or whatever) that would be fetched every frame and played back, e.g. having 128 bytes of samples would result in a sound quality of 7680hz, which is way better than what is currently possible, but still sounds retro enough, and can be used for any audio related stuff, like custom synths, ability to play voice clips for sfx, generative audio stuff, etc.

[nesbox]

I think it's a good idea, I implemented PCM support on this branch https://github.com/nesbox/TIC-80/tree/pcm, the binaries will be soon here https://github.com/nesbox/TIC-80/actions/runs/8402082845

Could someone test it and give us feedback?
To write to the PCM buffer please use poke(0x14E24, value) command.

[Weeppiko]

I did a small test with a saw wave and noticed it doesn't reach the bottom part of the phase, I suppose the value can be threated as a signed byte instead (-128 to 127)

[nesbox]

Please try to check the build from the main branch, because I already merged the PCM feature where I used 0-255 values.
Thanks.

[Weeppiko]

Sounded a bit quieter, but I think it is fine overall.

[nesbox]

A very simple example on JS to generate a sin wave using PCM

// script:js

let t=0
function TIC()
{
	cls(13)
	for(let i=0;i<128;i++)
		poke(0x14E24+i,(Math.sin(t*128+i)+1)*128)

	t++
}

[MineRobber9000]

So what sample rate are we talking about here? 128 samples per frame * 60 frames per second would indicate 7680Hz?

EDIT: nevermind, just read the original post. nice!

[Weeppiko]

In case anyone wondering how it sounds:
new_pcm.zip

[hanamileh-DEV]

This has just invalidated all my work on creating an aPCM that tries to produce the most perfect sound possible using sound registers ,_,

[Skeptim]

That doesn't make it any less of a feat ^^

[nesbox]

I don’t think this invalidated your awesome work, I think people won’t be able to load a lot of data into the PCM channel to play music, but it definitely increases the scope for creativity using generative audio and etc.