g711

> A JavaScript Audio Codec for G711A/G711U/PCM. Pure javascript implements, no any other 3rd-party library required.

PCM to G711A

`` ts
export function alawFromPCM(data: Int16Array | Int8Array): Uint8Array;

`




G711A to PCM


` ts

export function alawToPCM(data: Uint8Array, bit?: number): Int8Array | Int16Array;

`


G711U to PCM


` ts

export function ulawToPCM(data: Uint8Array, bit?: number): Int8Array;

`


PCM to G711U


` ts
export function ulawFromPCM(data: Int16Array | Int8Array): Uint8Array;

export type NumChannels = 1 | 2;
export type SampleBits = 8 | 16;
export type SampleRate = 8000 | 11025 | 16000 | 22050 | 24000 | 44100 | 48000;

`


PCM to WAV


` ts
/**
* 编码wav，一般wav格式是在pcm文件前增加44个字节的文件头，
* 所以，此处只需要在pcm数据前增加下就行了。
*
* @param {DataView} bytes pcm二进制数据
* @param {number} sampleRate 输入采样率
* @param {number} numChannels 声道数
* @param {number} sampleBits 输出采样位数
* @param {boolean} littleEndian 是否是小端字节序
* @returns {ArrayBuffer} wav二进制数据
*/
export function encodeWAV(bytes: DataView, sampleRate?: SampleRate, numChannels?: NumChannels, sampleBits?: SampleBits, littleEndian?: boolean): ArrayBuffer;

`




DEMO

` js

const audioUrl = './8k_1_16.g711u'; // 8KHZ 单声道 16-bit
const res = await fetch(audioUrl);
const arrayBuffer = await res.arrayBuffer(); // byte array字节数组
const i16A = ulawToPCM(new Uint8Array(arrayBuffer),16)
const wavBuf = encodeWAV(new DataView(i16A.buffer), 8000, 1, 16) // 8KHZ 单声道 16-bit
// const wavBuf = encodeWAV(new DataView(i16A.buffer), 16000, 2, 16) // 16KHZ 双声道 16-bit
const ctx = new (window.AudioContext || window.webkitAudioContext())();
const audioBuffer = await ctx.decodeAudioData(wavBuf, decodeData => decodeData, err => console.error(err));
const source = ctx.createBufferSource()
source.buffer = audioBuffer; // 设置数据
source.loop = false; //设置，循环播放
source.connect(ctx.destination); // 头尾相连
source.start(0); //立即播放
``

参考 C++ 版，感谢！

https://github.com/dreamisdream/audioTransfromTools