music.playInstructions() missing?

Arcade Help
1

https://arcade.makecode.com/developer/sound#sound-instructions mentions a music.playInstructions() API, does that currently work?

For background, I wanted to try modifying a white noise effect. The playMelody API works using music.playMelody("~5 !200", 60), but it’s not very flexible.

I tried creating a sound instruction buffer, but got stuck trying to play it:

const mySound: Buffer = hex`0500010102027f7f00000101`;
music.playInstructions(mySound)

This shows an error in the editor: Property ‘playInstructions’ does not exist on type ‘typeof music’.

I poked around in pxt-common-packages/blob/master/libs/mixer/melody.ts , and it doesn’t look as if playInstructions(buffer) exists. There’s a queuePlayInstructions(when, buffer), but that’s apparently not exported?

Am I missing something, or is this currently not implemented?

As a side note, it seems that the noise output ignores the frequency. That seems by design for white noise, but it’s not very flexible. Would you be open to adding a simple square wave + pseudorandom selector combination, similar to what the 8-bit Atari POKEY chip used? See https://www.atariarchives.org/dere/chapt07.php for more discussion of that. Maybe expose this as a new implementation of the removed-but-still-documented metallic waveform? (See pxt-common-packages PR #875.)

2

Ah, sorry! I think you found the correct function and at some point we made it private.

Add this to your project to get it back:

namespace music {
    //% shim=music::queuePlayInstructions
    export function playInstructions(timeDelta: number, buf: Buffer) { }
}

The actual function is implemented in C++, that’s why there’s no body. The shim annotation tells the compiler to link things up correctly.

3

Thanks, that works perfectly. In case it helps someone else, here’s my current sound effect after some tweaking:

// ww = waveform
// ffFF = frequency, low byte first
// ddDD = duration in milliseconds
// vvVV = volume
// wwWW = end volume
// ggGG = end frequency 
//                          ww--ffFFddDDvvVVwwWWggGG
const mySound: Buffer = hex`050001010101111100000101`;
music.playInstructions(0, mySound)
4

Also, here’s some code you might find useful:

I wrote this a while ago. It’s a snippet of code to generate sound buffers with separate envelopes for amplitude and pitch. Press A to here a sound effect