From 1606eb57d2f7d70fa899f338c354d28ef1df49a7 Mon Sep 17 00:00:00 2001
From: Intel A80486DX2-66 <larry.holst@disroot.org>
Date: Fri, 29 Dec 2023 19:55:56 +0300
Subject: [PATCH] add js-programming/bytebeat-render.js

---
 js-programming/bytebeat-render.js | 113 ++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 js-programming/bytebeat-render.js

diff --git a/js-programming/bytebeat-render.js b/js-programming/bytebeat-render.js
new file mode 100644
index 0000000..3ac94d2
--- /dev/null
+++ b/js-programming/bytebeat-render.js
@@ -0,0 +1,113 @@
+/*
+Node.JS: Bytebeat generator
+
+Note: Calls `ffmpeg` to convert output raw audio to a WAVE file
+
+Warning: The current result is quick and dirty. Not for educational or
+production purposes.
+
+To-Do: Fix signed bytebeat and floatbeat
+To-Do: (cosmetic) Wrap the code before 81th column
+*/
+
+const { appendFileSync, unlinkSync, writeFileSync } = require("fs")
+const { tmpdir } = require("os")
+const { execSync } = require("child_process")
+const { basename } = require("path")
+
+let BUFFER_SIZE = 65536 // feel free to change this
+const LIGHTNING_MODE = false // disables sequential file write optimization, feel free to change this
+
+const SAMPLE_RATE = 8000 // feel free to change this
+const SECONDS = 30 // feel free to change this
+const CHANNELS = 1 // feel free to change this
+
+const FINAL_SAMPLE_RATE = 44100 // feel free to change this
+const FINAL_SAMPLE_RATE_CONVERSION = SAMPLE_RATE / FINAL_SAMPLE_RATE / CHANNELS
+const SAMPLES = SECONDS * FINAL_SAMPLE_RATE // feel free to change this
+const PRODUCT = SAMPLES * CHANNELS
+BUFFER_SIZE = LIGHTNING_MODE ? PRODUCT : BUFFER_SIZE
+
+const TYPE_BYTEBEAT = 0
+const TYPE_SIGNED_BYTEBEAT = 1
+const TYPE_FLOATBEAT = 2
+
+const SELECTED_TYPE = TYPE_BYTEBEAT // feel free to change this
+
+// for bytebeat
+const int = x => Math.floor(x)
+const abs = Math.abs
+const cbrt = Math.cbrt
+const cos = Math.cos
+const cosh = Math.cosh
+const floor = Math.floor
+const log = Math.log
+const log2 = Math.log2
+const PI = Math.PI
+const pow = Math.pow
+const random = Math.random
+const sin = Math.sin
+const sinh = Math.sinh
+const sqrt = Math.sqrt
+const tan = Math.tan
+const tanh = Math.tanh
+
+const generateAudio = t => {
+	t *= FINAL_SAMPLE_RATE_CONVERSION
+	return t&t>>8
+}
+
+const constrainValue = sample => {
+	switch (SELECTED_TYPE) {
+	case TYPE_BYTEBEAT:
+		return sample & 255
+	case TYPE_SIGNED_BYTEBEAT:
+		return ((sample + 127) & 255) - 128
+	case TYPE_FLOATBEAT:
+		return floor(sample * 127) + 127
+	}
+}
+
+const random_choice = choices => choices[Math.floor(Math.random() * choices.length)]
+
+const randomFileNameAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-"
+
+const generateRandomFileName = () => {
+	let res = tmpdir() + "/" + basename(__filename) + "_"
+	for (let i = 0; i < 64; i++)
+		res += random_choice(randomFileNameAlphabet)
+	return res
+}
+
+let t = 0
+
+let fileName = generateRandomFileName()
+writeFileSync(fileName, Buffer.alloc(0))
+
+// the loop of sequential file writing, created to ease load on RAM
+for (let buffer = 0; t < PRODUCT; buffer++) {
+	let audioData = new Uint8Array(BUFFER_SIZE)
+
+	let idx = 0
+	for (; idx < BUFFER_SIZE && t < PRODUCT; idx++) {
+		let sample = generateAudio(t)
+		if (sample.constructor === Array)
+			sample.forEach((sample, index) => {
+				audioData[CHANNELS * idx + index] = constrainValue(sample);
+			})
+		else
+			audioData[idx] = constrainValue(sample);
+		t++;
+	}
+
+	if (t >= PRODUCT) {
+		let truncatedArray = new Uint8Array(idx)
+		truncatedArray.set(audioData.subarray(0, idx))
+		audioData = truncatedArray
+	}
+
+	appendFileSync(fileName, Buffer.from(audioData.buffer))
+}
+
+execSync(`ffmpeg -f u8 -ar ${FINAL_SAMPLE_RATE} -ac ${CHANNELS} -i ${fileName} output_${+new Date()}.wav -y`)
+unlinkSync(fileName)