使用AudioRenderer开发音频播放功能

import audio from '@ohos.multimedia.audio'; 
import fs from '@ohos.file.fs'; 
import common from '@ohos.app.ability.common'; 
import { Context } from '@ohos.abilityAccessCtrl'; 
  
const TAG = 'AudioRendererDemo'; 
  
export class AudioRendererHelper { 
  
  static instance = new AudioRendererHelper() 
  private context: Context; 
  private renderModel: audio.AudioRenderer | undefined = undefined; 
  private audioStreamInfo: audio.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 audioRendererInfo: audio.AudioRendererInfo = { 
    usage: audio.StreamUsage.STREAM_USAGE_VOICE_COMMUNICATION, 
    rendererFlags: 0 
  }; 
  
  private audioRendererOptions: audio.AudioRendererOptions = { 
    streamInfo: this.audioStreamInfo, 
    rendererInfo: this.audioRendererInfo 
  }; 
  
  
  // 开始一次音频渲染 
  async start(name: string,context:  Context = null ) { 
  
  
    this.context = context; 
    this.renderModel = await audio.createAudioRenderer(this.audioRendererOptions); 
  
  
    if (this.renderModel !== undefined) { 
      let stateGroup = [audio.AudioState.STATE_PREPARED, audio.AudioState.STATE_PAUSED, audio.AudioState.STATE_STOPPED]; 
      if (stateGroup.indexOf((this.renderModel as audio.AudioRenderer).state.valueOf()) === -1) { // 当且仅当状态为prepared、paused和stopped之一时才能启动渲染 
        console.error(TAG + 'start failed'); 
        return; 
      } 
      await (this.renderModel as audio.AudioRenderer).start(); // 启动渲染 
  
      const bufferSize = await (this.renderModel as audio.AudioRenderer).getBufferSize(); 
  
      let path = this.context.filesDir; 
      const filePath = path + name; // 使用沙箱路径获取文件，实际路径为/data/storage/el2/base/haps/entry/files/test.wav 
      console.info("*****************************************") 
      console.info(filePath) 
      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); 
  
      class Options { 
        offset: number = 0; 
        length: number = 0 
      } 
  
      for (let i = 0; i < len; i++) { 
        let options: Options = { 
          offset: i * bufferSize, 
          length: bufferSize 
        }; 
        let readsize = await fs.read(file.fd, buf, options); 
  
        // buf是要写入缓冲区的音频数据，在调用AudioRenderer.write()方法前可以进行音频数据的预处理，实现个性化的音频播放功能，AudioRenderer会读出写入缓冲区的音频数据进行渲染 
  
        let writeSize: number = await (this.renderModel as audio.AudioRenderer).write(buf); 
        if ((this.renderModel as audio.AudioRenderer).state.valueOf() === audio.AudioState.STATE_RELEASED) { // 如果渲染器状态为released，关闭资源 
          fs.close(file); 
        } 
        if ((this.renderModel as audio.AudioRenderer).state.valueOf() === audio.AudioState.STATE_RUNNING) { 
          if (i === len - 1) { // 如果音频文件已经被读取完，停止渲染 
            fs.close(file); 
            await (this.renderModel as audio.AudioRenderer).stop(); 
            if ((this.renderModel as audio.AudioRenderer).state.valueOf() === audio.AudioState.STATE_STOPPED) { 
              console.info('Renderer stopped.'); 
            } else { 
              console.error('Stopping renderer failed.'); 
            } 
          } 
        } 
      } 
    } 
  } 
  
  // 停止渲染 
  async stop() { 
    if (this.renderModel !== undefined) { 
      // 只有渲染器状态为running或paused的时候才可以停止 
      if ((this.renderModel as audio.AudioRenderer).state.valueOf() !== audio.AudioState.STATE_RUNNING && (this.renderModel as audio.AudioRenderer).state.valueOf() !== audio.AudioState.STATE_PAUSED) { 
        console.info('Renderer is not running or paused.'); 
        return; 
      } 
      await (this.renderModel as audio.AudioRenderer).stop(); // 停止渲染 
      if ((this.renderModel as audio.AudioRenderer).state.valueOf() === audio.AudioState.STATE_STOPPED) { 
        console.info('Renderer stopped.'); 
      } else { 
        console.error('Stopping renderer failed.'); 
      } 
    } 
  } 
  
  // 销毁实例，释放资源 
  async release() { 
    if (this.renderModel !== undefined) { 
      // 渲染器状态不是released状态，才能release 
      if (this.renderModel.state.valueOf() === audio.AudioState.STATE_RELEASED) { 
        console.info('Renderer already released'); 
        return; 
      } 
      await this.renderModel.release(); // 释放资源 
      if (this.renderModel.state.valueOf() === audio.AudioState.STATE_RELEASED) { 
        console.info('Renderer released'); 
      } else { 
        console.error('Renderer release failed.'); 
      } 
    } 
  
  
  } 
} 
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