使用AudioRenderer開發(fā)音頻播放功能

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

const TAG = 'AudioRendererDemo';

export default class AudioRendererDemo {
  private renderModel = undefined;
  private audioStreamInfo = {
    samplingRate: audio.AudioSamplingRate.SAMPLE_RATE_48000, // 采樣率
    channels: audio.AudioChannel.CHANNEL_2, // 通道
    sampleFormat: audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE, // 采樣格式
    encodingType: audio.AudioEncodingType.ENCODING_TYPE_RAW // 編碼格式
  }
  private audioRendererInfo = {
    content: audio.ContentType.CONTENT_TYPE_MUSIC, // 媒體類型
    usage: audio.StreamUsage.STREAM_USAGE_MEDIA, // 音頻流使用類型
    rendererFlags: 0 // 音頻渲染器標志
  }
  private audioRendererOptions = {
    streamInfo: this.audioStreamInfo,
    rendererInfo: this.audioRendererInfo
  }

  // 初始化，創(chuàng)建實例，設(shè)置監(jiān)聽事件
  init() {
    audio.createAudioRenderer(this.audioRendererOptions, (err, renderer) => { // 創(chuàng)建AudioRenderer實例
      if (!err) {
        console.info(`${TAG}: creating AudioRenderer success`);
        this.renderModel = renderer;
        this.renderModel.on('stateChange', (state) => { // 設(shè)置監(jiān)聽事件，當(dāng)轉(zhuǎn)換到指定的狀態(tài)時觸發(fā)回調(diào)
          if (state == 2) {
            console.info('audio renderer state is: STATE_RUNNING');
          }
        });
        this.renderModel.on('markReach', 1000, (position) => { // 訂閱markReach事件，當(dāng)渲染的幀數(shù)達到1000幀時觸發(fā)回調(diào)
          if (position == 1000) {
            console.info('ON Triggered successfully');
          }
        });
      } else {
        console.info(`${TAG}: creating AudioRenderer failed, error: ${err.message}`);
      }
    });
  }

  // 開始一次音頻渲染
  async start() {
    let stateGroup = [audio.AudioState.STATE_PREPARED, audio.AudioState.STATE_PAUSED, audio.AudioState.STATE_STOPPED];
    if (stateGroup.indexOf(this.renderModel.state) === -1) { // 當(dāng)且僅當(dāng)狀態(tài)為prepared、paused和stopped之一時才能啟動渲染
      console.error(TAG + 'start failed');
      return;
    }
    await this.renderModel.start(); // 啟動渲染

    const bufferSize = await this.renderModel.getBufferSize();
    let context = getContext(this);
    let path = context.filesDir;
    const filePath = path + '/test.wav'; // 使用沙箱路徑獲取文件，實際路徑為/data/storage/el2/base/haps/entry/files/test.wav

    let file = fs.openSync(filePath, fs.OpenMode.READ_ONLY);
    let stat = await fs.stat(filePath);
    let buf = new ArrayBuffer(bufferSize);
    let len = stat.size % bufferSize === 0 ? Math.floor(stat.size / bufferSize) : Math.floor(stat.size / bufferSize + 1);
    for (let i = 0; i < len; i++) {
      let options = {
        offset: i * bufferSize,
        length: bufferSize
      };
      let readsize = await fs.read(file.fd, buf, options);

      // buf是要寫入緩沖區(qū)的音頻數(shù)據(jù)，在調(diào)用AudioRenderer.write()方法前可以進行音頻數(shù)據(jù)的預(yù)處理，實現(xiàn)個性化的音頻播放功能，AudioRenderer會讀出寫入緩沖區(qū)的音頻數(shù)據(jù)進行渲染

      let writeSize = await new Promise((resolve, reject) => {
        this.renderModel.write(buf, (err, writeSize) => {
          if (err) {
            reject(err);
          } else {
            resolve(writeSize);
          }
        });
      });
      if (this.renderModel.state === audio.AudioState.STATE_RELEASED) { // 如果渲染器狀態(tài)為released，停止渲染
        fs.close(file);
        await this.renderModel.stop();
      }
      if (this.renderModel.state === audio.AudioState.STATE_RUNNING) {
        if (i === len - 1) { // 如果音頻文件已經(jīng)被讀取完，停止渲染
          fs.close(file);
          await this.renderModel.stop();
        }
      }
    }
  }

  // 暫停渲染
  async pause() {
    // 只有渲染器狀態(tài)為running的時候才能暫停
    if (this.renderModel.state !== audio.AudioState.STATE_RUNNING) {
      console.info('Renderer is not running');
      return;
    }
    await this.renderModel.pause(); // 暫停渲染
    if (this.renderModel.state === audio.AudioState.STATE_PAUSED) {
      console.info('Renderer is paused.');
    } else {
      console.error('Pausing renderer failed.');
    }
  }

  // 停止渲染
  async stop() {
    // 只有渲染器狀態(tài)為running或paused的時候才可以停止
    if (this.renderModel.state !== audio.AudioState.STATE_RUNNING && this.renderModel.state !== audio.AudioState.STATE_PAUSED) {
      console.info('Renderer is not running or paused.');
      return;
    }
    await this.renderModel.stop(); // 停止渲染
    if (this.renderModel.state === audio.AudioState.STATE_STOPPED) {
      console.info('Renderer stopped.');
    } else {
      console.error('Stopping renderer failed.');
    }
  }

  // 銷毀實例，釋放資源
  async release() {
    // 渲染器狀態(tài)不是released狀態(tài)，才能release
    if (this.renderModel.state === audio.AudioState.STATE_RELEASED) {
      console.info('Renderer already released');
      return;
    }
    await this.renderModel.release(); // 釋放資源
    if (this.renderModel.state === audio.AudioState.STATE_RELEASED) {
      console.info('Renderer released');
    } else {
      console.error('Renderer release failed.');
    }
  }
}