使用AudioCapturer開發(fā)音頻錄制功能

import audio from '@ohos.multimedia.audio';
import fs from '@ohos.file.fs';

const TAG = 'AudioCapturerDemo';

export default class AudioCapturerDemo {
  private audioCapturer = undefined;
  private audioStreamInfo = {
    samplingRate: audio.AudioSamplingRate.SAMPLE_RATE_44100,
    channels: audio.AudioChannel.CHANNEL_1,
    sampleFormat: audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE,
    encodingType: audio.AudioEncodingType.ENCODING_TYPE_RAW
  }
  private audioCapturerInfo = {
    source: audio.SourceType.SOURCE_TYPE_MIC, // 音源類型
    capturerFlags: 0 // 音頻采集器標志
  }
  private audioCapturerOptions = {
    streamInfo: this.audioStreamInfo,
    capturerInfo: this.audioCapturerInfo
  }

  // 初始化，創(chuàng)建實例，設置監(jiān)聽事件
  init() {
    audio.createAudioCapturer(this.audioCapturerOptions, (err, capturer) => { // 創(chuàng)建AudioCapturer實例
      if (err) {
        console.error(`Invoke createAudioCapturer failed, code is ${err.code}, message is ${err.message}`);
        return;
      }

      console.info(`${TAG}: create AudioCapturer success`);
      this.audioCapturer = capturer;
      this.audioCapturer.on('markReach', 1000, (position) => { // 訂閱markReach事件，當采集的幀數(shù)達到1000時觸發(fā)回調
        if (position === 1000) {
          console.info('ON Triggered successfully');
        }
      });
      this.audioCapturer.on('periodReach', 2000, (position) => { // 訂閱periodReach事件，當采集的幀數(shù)達到2000時觸發(fā)回調
        if (position === 2000) {
          console.info('ON Triggered successfully');
        }
      });

    });
  }

  // 開始一次音頻采集
  async start() {
    let stateGroup = [audio.AudioState.STATE_PREPARED, audio.AudioState.STATE_PAUSED, audio.AudioState.STATE_STOPPED];
    if (stateGroup.indexOf(this.audioCapturer.state) === -1) { // 當且僅當狀態(tài)為STATE_PREPARED、STATE_PAUSED和STATE_STOPPED之一時才能啟動采集
      console.error(`${TAG}: start failed`);
      return;
    }
    await this.audioCapturer.start(); // 啟動采集

    let context = getContext(this);
    const path = context.filesDir + '/test.wav'; // 采集到的音頻文件存儲路徑

    let file = fs.openSync(path, 0o2 | 0o100); // 如果文件不存在則創(chuàng)建文件
    let fd = file.fd;
    let numBuffersToCapture = 150; // 循環(huán)寫入150次
    let count = 0;
    while (numBuffersToCapture) {
      let bufferSize = await this.audioCapturer.getBufferSize();
      let buffer = await this.audioCapturer.read(bufferSize, true);
      let options = {
        offset: count * bufferSize,
        length: bufferSize
      };
      if (buffer === undefined) {
        console.error(`${TAG}: read buffer failed`);
      } else {
        let number = fs.writeSync(fd, buffer, options);
        console.info(`${TAG}: write date: ${number}`);
      }
      numBuffersToCapture--;
      count++;
    }
  }

  // 停止采集
  async stop() {
    // 只有采集器狀態(tài)為STATE_RUNNING或STATE_PAUSED的時候才可以停止
    if (this.audioCapturer.state !== audio.AudioState.STATE_RUNNING && this.audioCapturer.state !== audio.AudioState.STATE_PAUSED) {
      console.info('Capturer is not running or paused');
      return;
    }
    await this.audioCapturer.stop(); // 停止采集
    if (this.audioCapturer.state === audio.AudioState.STATE_STOPPED) {
      console.info('Capturer stopped');
    } else {
      console.error('Capturer stop failed');
    }
  }

  // 銷毀實例，釋放資源
  async release() {
    // 采集器狀態(tài)不是STATE_RELEASED或STATE_NEW狀態(tài)，才能release
    if (this.audioCapturer.state === audio.AudioState.STATE_RELEASED || this.audioCapturer.state === audio.AudioState.STATE_NEW) {
      console.info('Capturer already released');
      return;
    }
    await this.audioCapturer.release(); // 釋放資源
    if (this.audioCapturer.state == audio.AudioState.STATE_RELEASED) {
      console.info('Capturer released');
    } else {
      console.error('Capturer release failed');
    }
  }
}