PCM-Effects

Manipulate, transform and add effects to your PCM streams

This package simplifies the process of manipulating PCM streams.

Using this package with discord.js is possible, as it was originally made for usage in discord bots.

Supported PCM stream type

• [x] s8
• [x] u8
• [x] s16le
• [ ] s16be
• [ ] u16le
• [ ] u16be
• [ ] s32le
• [ ] s32be
• [ ] u32le
• [ ] u32be

Usage example

import PCMEffects from 'pcm-effects';//Importing the module

//--- Create a ffmpeg process to get a PCM stream ---//
const ffmpeg = child_process.spawn('ffmpeg', [
	'-i', ANY_INPUT_OR_STDIN,
	'-analyzeduration', '0',
	'-loglevel', '0',
	'-f', 's16le',//Required : set the PCM stream type
	'-ar', '48000',//Sample rate: not useful for PCM-Effects, but may need be to changed depending on the use case (ex: Discord voice require 48000Hz)
	'-ac', '2',//Force the input to be in stereo
	'pipe:1'//Redirect the output to stdout
], {
	shell: false,
	windowsHide: true
});
//---//

//--- PCM-Effects ---//
const pcm = new PCMEffects("s16le");//Create a new instance of PCM-Effects
pcm.setVolume(1);//Change the volume, can be changed during playing
pcm.setDistortion(1);//Change the distortion, can be changed during playing
ffmpeg.stdout.pipe(pcm);//Redirect the output of ffmpeg to the input of the PCM-Effects class
//---//

//--- Using the output in Discord.js ---//
const prism = require('prism-media');
const { createAudioResource } = require('discord.js');

const encoder = new prism.opus.Encoder({channels: 2, rate: 48000, frameSize: 960});//Encode the PCM stream in Opus format
pcm.pipe(encoder);//Pass the PCM-Effects stream to the encoder
let resource = createAudioResource(encoder, {inputType: "opus"});//Create a Discord.js audioResource
//You can now use this resource in Discord.js (see https://discordjs.guide/voice/audio-resources.html)
//---//

API

PCMEffects.Merge(type, ...streams)

Merge two PCMEffects streams together, and return a new one with his own effects control.

Warning : The first stream should not interrupt transmission, because frames are synced based on it. If this stream cease to emit, sound of the others streams will not be processed

Example :

const pcm1 = new PCMEffects("s16le");
const pcm2 = new PCMEffects("s16le");
const new_pcm = PCMEffects.Merge("s16le", pcm1, pcm2);

Arguments :

• type : The stream type. Possibles values are listed in Supported PCM stream type
• streams : An indefinite list of PCMEffects streams

new PCMEffects(type)

Initialize the PCM.

The returned class extends Transform, the class is also a readable and a writable stream.

Example : const pcm = new PCMEffects("s16le")

Arguments :

• type : The stream type. Possibles values are listed in Supported PCM stream type

pcm.setVolume(level)

Set the volume of the stream.

This setting can be changed at any moment

Example : pcm.setVolume(2)//The volume is double as original

Arguments :

• level : Volume level. This value multiplies the actual volume (0.5 play at half the volume, 2 double it)

pcm.setDistortion(level)

Set the distortion of the stream.

This setting can be changed at any moment

Example : pcm.setSaturation(60)//The volume is double as original

Arguments :

• level : Distortion threshold in percent. The volume is limited to this threshold

Help and disclaimer

To have a preview of this module working, take a look at the discord bot BaBot (Source code).

I'm far from being expert in programming and, especially in this package, my code is dirty and buggy.

But feel free :

• To report any issues in this Github repo
• To make code changes
• To contact me for any questions or suggestions : Theirémi#4835, BaBot server