audio scripts

blob_buffer_audio.js

// 录音数据是共享内存的，所以在一个回调事件内是有效的
// 下一个回调事件内则会把上一份数据覆盖
const f32 = event.inputBuffer.getChannelData(0);
// 复制一份内存数据
const f32Ret = new Float32Array(f32);


// 把一个音频文件切片，分次上传
this.http.get('http://local.yuanfudao.ws:3000/assets/rec-001.wav', {
    responseType: 'blob'
}).pipe(
    switchMap(blob => {
        const fileSize = blob.size;
        console.log('fileSize: ', fileSize);
        let start = 44;
        const blobList = [];
        while(start < fileSize) {
            const end = start + 5000 > fileSize ? fileSize : start + 5000;
            blobList.push(blob.slice(start, end));
            start = end;
        }
        return zip(...blobList.map(item => new Observable(observer => {
            const reader = new FileReader();
            reader.onload = (e: any) => {
                const base64=(/.+;\s*base64\s*,\s*(.+)$/i.exec(e.target.result)||[])[1];
                observer.next(base64);
            }
            reader.readAsDataURL(item);
        }) as Observable<string>
        ))
    }),
    tap((base64Arr: string[]) => {
        console.log('tap tap', base64Arr);
        this.wsSubject.next({type: 1, text: 'xxx', params: {audioType: 'pcm'}});
        let index = 0;
        const length = base64Arr.length;
        const timer = setInterval(() => {
            console.log('setInterval', index);
            if (index < length) {
                this.wsSubject.next({type: 2, packet: base64Arr[index], packetIndex: index});
                index ++;
            } else {
                clearInterval(timer);
                this.wsSubject.next({type: 3});
            }
        }, 500);
    }),
    catchError(e => {
        console.log('eeee', e);
        return of(null);
    })
).subscribe();

// 合并多批次的数据为一个Float32Array
// 并把Float32Array转成Int16Array
private transArr32to16WithStep(bufferArr: Float32Array[][]) {
    const f32ArrArr = bufferArr.map(b => b[0]); // 取单声道的数据
    const totalLength = f32ArrArr.reduce((len, f32) => len + f32.length, 0);
    const f32Arr = new Float32Array(totalLength);
    let offset = 0;
    for (let i = 0; i < f32ArrArr.length; i++) {
        f32Arr.set(f32ArrArr[i], offset);
        offset += f32ArrArr[i].length;
    }
    const int16Arr = new Int16Array(totalLength);
    for (let i = 0; i < totalLength; i++) {
        let s = Math.max(-1, Math.min(1, f32Arr[i]));
        s = s < 0 ? s * 0x8000 : s * 0x7FFF;
        int16Arr[i] = s;
    }
    return int16Arr;
}

// 把Int16Array转成wav文件
// 其实就是加上了wav文件头
private getWavFileFromBuffer(buffer16: Int16Array) {
  console.log('buffer16 length', buffer16.length);
  const size = buffer16.length;
  const sampleRate = 16000;
  const bitRate = 16;

  // 编码数据 https://github.com/mattdiamond/Recorderjs https://www.cnblogs.com/blqw/p/3782420.html https://www.cnblogs.com/xiaoqi/p/6993912.html
  const dataLength = size * ( bitRate / 8 );
  const buffer = new ArrayBuffer(44 + dataLength);
  const data = new DataView(buffer);

  let offset = 0;
  const writeString = function(str) {
      for (let i = 0; i < str.length; i++, offset++) {
          data.setUint8(offset, str.charCodeAt(i));
      };
  };
  const write16 = function(v) {
      data.setUint16(offset, v, true);
      offset += 2;
  };
  const write32 = function(v) {
      data.setUint32(offset, v, true);
      offset += 4;
  };

  /* RIFF identifier */
  writeString('RIFF');
  /* RIFF chunk length */
  write32(36 + dataLength);
  /* RIFF type */
  writeString('WAVE');
  /* format chunk identifier */
  writeString('fmt ');
  /* format chunk length */
  write32(16);
  /* sample format (raw) */
  write16(1);
  /* channel count */
  write16(1);
  /* sample rate */
  write32(sampleRate);
  /* byte rate (sample rate * block align) */
  write32(sampleRate * (bitRate / 8));
  /* block align (channel count * bytes per sample) */
  write16(bitRate / 8);
  /* bits per sample */
  write16(bitRate);
  /* data chunk identifier */
  writeString('data');
  /* data chunk length */
  write32(dataLength);
  // 写入采样数据
  for (let i = 0; i < size; i++, offset += 2) {
      data.setInt16(offset, buffer16[i], true);
  };

  console.log(data.buffer);

  const blob = new Blob([data.buffer], { type: 'audio/wav' })
  const blobUrl = URL.createObjectURL(blob);
  // @ts-ignore
  document.querySelector('#audio-node-hgm').src = blobUrl;
  const link = document.createElement('a');
  link.href = blobUrl;
  link.download = 'hello1.wav';
  document.body.appendChild(link);
  link.dispatchEvent(new MouseEvent('click', {
      bubbles: true,
      cancelable: true,
      view: window
  }))
}

// 使用btoa编码buffer到base64
const buffer16 = new ArrayBuffer(buffer32.length * 2);
const base64String = btoa(String.fromCharCode(...new Uint8Array(buffer16.buffer)));
// 使用第三方库编码
import {encode} from 'base64-arraybuffer'
const base64String = encode(buffer16);
// 使用FileReader Api读取buffer
const blob = new Blob([buffer]);
const reader = new FileReader();
reader.onloadend = (e: any) => {
    // @ts-ignore
    const base64 = (/.+;\s*base64\s*,\s*(.+)$/i.exec(reader.result) || [])[1];
}
reader.readAsDataURL(blob);