AudioCapturer录音+AudioRenderer播放音频？

Question

问题来源

根据AudioCapture示例代码实现录音功能，发现录音生成的.wav文件在windows上无法播放。

Answer 1

问题分析过程

首先按照官网文档，实现AudioCapture音频录制

import audio from '@ohos.multimedia.audio';
import fs from '@ohos.file.fs';
 
const TAG = 'AudioCapturerDemo';
let context = getContext(this);
 
let audioCapturer: audio.AudioCapturer | undefined = undefined;
let 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
}
let audioCapturerInfo: audio.AudioCapturerInfo = {
  source: audio.SourceType.SOURCE_TYPE_MIC, // 音源类型
  capturerFlags: 0 // 音频采集器标志
}
let audioCapturerOptions: audio.AudioCapturerOptions = {
  streamInfo: audioStreamInfo,
  capturerInfo: audioCapturerInfo
}
 
// 初始化，创建实例，设置监听事件
async function init() {
  audio.createAudioCapturer(audioCapturerOptions, (err, capturer) => { // 创建AudioCapturer实例
    if (err) {
      console.error(`Invoke createAudioCapturer failed, code is ${err.code}, message is ${err.message}`);
      return;
    }
    console.info(`${TAG}: create AudioCapturer success`);
    audioCapturer = capturer;
    if (audioCapturer !== undefined) {
      (audioCapturer as audio.AudioCapturer).on('markReach', 1000, (position: number) => { // 订阅markReach事件，当采集的帧数达到1000时触发回调
        if (position === 1000) {
          console.info('ON Triggered successfully');
        }
      });
      (audioCapturer as audio.AudioCapturer).on('periodReach', 2000, (position: number) => { // 订阅periodReach事件，当采集的帧数达到2000时触发回调
        if (position === 2000) {
          console.info('ON Triggered successfully');
        }
      });
    }
  });
}
 
// 开始一次音频采集
async function start() {
  if (audioCapturer !== undefined) {
    let stateGroup = [audio.AudioState.STATE_PREPARED, audio.AudioState.STATE_PAUSED, audio.AudioState.STATE_STOPPED];
    if (stateGroup.indexOf((audioCapturer as audio.AudioCapturer).state.valueOf()) === -1) { // 当且仅当状态为STATE_PREPARED、STATE_PAUSED和STATE_STOPPED之一时才能启动采集
      console.error(`${TAG}: start failed`);
      return;
    }
    await (audioCapturer as audio.AudioCapturer).start(); // 启动采集
    const path = context.filesDir + '/test.wav'; // 采集到的音频文件存储路径
    let file: fs.File = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE); // 如果文件不存在则创建文件
    let fd = file.fd;
    let numBuffersToCapture = 150; // 循环写入150次
    let count = 0;
    class Options {
      offset: number = 0;
      length: number = 0
    }
    while (numBuffersToCapture) {
      let bufferSize = await (audioCapturer as audio.AudioCapturer).getBufferSize();
      let buffer = await (audioCapturer as audio.AudioCapturer).read(bufferSize, true);
      let options: Options = {
        offset: count * bufferSize,
        length: bufferSize
      };
      if (buffer === undefined) {
        console.error(`${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 function stop() {
  if (audioCapturer !== undefined) {
    // 只有采集器状态为STATE_RUNNING或STATE_PAUSED的时候才可以停止
    if ((audioCapturer as audio.AudioCapturer).state.valueOf() !== audio.AudioState.STATE_RUNNING && (audioCapturer as audio.AudioCapturer).state.valueOf() !== audio.AudioState.STATE_PAUSED) {
      console.info('Capturer is not running or paused');
      return;
    }
    await (audioCapturer as audio.AudioCapturer).stop(); // 停止采集
    if ((audioCapturer as audio.AudioCapturer).state.valueOf() === audio.AudioState.STATE_STOPPED) {
       console.info('Capturer stopped');
    } else {
       console.error('Capturer stop failed');
    }
  }
}
 
// 销毁实例，释放资源
async function release() {
  if (audioCapturer !== undefined) {
    // 采集器状态不是STATE_RELEASED或STATE_NEW状态，才能release
    if ((audioCapturer as audio.AudioCapturer).state.valueOf() === audio.AudioState.STATE_RELEASED || (audioCapturer as audio.AudioCapturer).state.valueOf() === audio.AudioState.STATE_NEW) {
      console.info('Capturer already released');
      return;
    }
    await (audioCapturer as audio.AudioCapturer).release(); // 释放资源
    if ((audioCapturer as audio.AudioCapturer).state.valueOf() === audio.AudioState.STATE_RELEASED) {
      console.info('Capturer released');
    } else {
      console.error('Capturer release failed');
    }
  }
}

查看文档得知，AudioCapturer是音频采集器，用于录制PCM（Pulse Code Modulation）音频数据。很多播放器无法直接播放。把test.wav文件导出到电脑端，使用Audacity软件，文件-\>导入-\>原始数据，选择了编码，采样率，声道后导入。可以播放该音频。

使用AudioRenderer播放PCM音频

AudioRenderer：用于音频输出的的ArkTS/JS API，仅支持PCM格式，需要应用持续写入音频数据进行工作。应用可以在输入前添加数据预处理，如设定音频文件的采样率、位宽等，要求开发者具备音频处理的基础知识，适用于更专业、更多样化的媒体播放应用开发。

示例代码

import audio from '@ohos.multimedia.audio';
import fs from '@ohos.file.fs';
 
const TAG = 'AudioRendererDemo';
 
let context = getContext(this);
let renderModel: audio.AudioRenderer | undefined = undefined;
let audioStreamInfo: audio.AudioStreamInfo = {
  samplingRate: audio.AudioSamplingRate.SAMPLE_RATE_48000, // 采样率
  channels: audio.AudioChannel.CHANNEL_2, // 通道
  sampleFormat: audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE, // 采样格式
  encodingType: audio.AudioEncodingType.ENCODING_TYPE_RAW // 编码格式
}
let audioRendererInfo: audio.AudioRendererInfo = {
  content: audio.ContentType.CONTENT_TYPE_MUSIC, // 媒体类型
  usage: audio.StreamUsage.STREAM_USAGE_MEDIA, // 音频流使用类型
  rendererFlags: 0 // 音频渲染器标志
}
let audioRendererOptions: audio.AudioRendererOptions = {
  streamInfo: audioStreamInfo,
  rendererInfo: audioRendererInfo
}
 
// 初始化，创建实例，设置监听事件
async function init() {
  audio.createAudioRenderer(audioRendererOptions, (err, renderer) => { // 创建AudioRenderer实例
    if (!err) {
      console.info(`${TAG}: creating AudioRenderer success`);
      renderModel = renderer;
      if (renderModel !== undefined) {
        (renderModel as audio.AudioRenderer).on('stateChange', (state: audio.AudioState) => { // 设置监听事件，当转换到指定的状态时触发回调
          if (state == 2) {
            console.info('audio renderer state is: STATE_RUNNING');
          }
        });
        (renderModel as audio.AudioRenderer).on('markReach', 1000, (position: number) => { // 订阅markReach事件，当渲染的帧数达到1000帧时触发回调
          if (position == 1000) {
            console.info('ON Triggered successfully');
          }
        });
      }
    } else {
      console.info(`${TAG}: creating AudioRenderer failed, error: ${err.message}`);
    }
  });
}
 
// 开始一次音频渲染
async function start() {
  if (renderModel !== undefined) {
    let stateGroup = [audio.AudioState.STATE_PREPARED, audio.AudioState.STATE_PAUSED, audio.AudioState.STATE_STOPPED];
    if (stateGroup.indexOf((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 (renderModel as audio.AudioRenderer).start(); // 启动渲染
    
    const bufferSize = await (renderModel as audio.AudioRenderer).getBufferSize();
    
    let path = context.filesDir;
    const filePath = path + '/test.wav'; // 使用沙箱路径获取文件，实际路径为/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);
    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 (renderModel as audio.AudioRenderer).write(buf);
        if ((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 ((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 (renderModel as audio.AudioRenderer).stop();
        }
      }
    }
  }
}
 
// 暂停渲染
async function pause() {
  if (renderModel !== undefined) {
    // 只有渲染器状态为running的时候才能暂停
    if ((renderModel as audio.AudioRenderer).state.valueOf() !== audio.AudioState.STATE_RUNNING) {
      console.info('Renderer is not running');
      return;
    }
    await (renderModel as audio.AudioRenderer).pause(); // 暂停渲染
    if ((renderModel as audio.AudioRenderer).state.valueOf() === audio.AudioState.STATE_PAUSED) {
      console.info('Renderer is paused.');
    } else {
      console.error('Pausing renderer failed.');
    }
  }
}
 
// 停止渲染
async function stop() {
  if (renderModel !== undefined) {
    // 只有渲染器状态为running或paused的时候才可以停止
    if ((renderModel as audio.AudioRenderer).state.valueOf() !== audio.AudioState.STATE_RUNNING && (renderModel as audio.AudioRenderer).state.valueOf() !== audio.AudioState.STATE_PAUSED) {
      console.info('Renderer is not running or paused.');
      return;
    }
    await (renderModel as audio.AudioRenderer).stop(); // 停止渲染
    if ((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 function release() {
  if (renderModel !== undefined) {
    // 渲染器状态不是released状态，才能release
    if (renderModel.state.valueOf() === audio.AudioState.STATE_RELEASED) {
      console.info('Renderer already released');
      return;
    }
    await renderModel.release(); // 释放资源
    if (renderModel.state.valueOf() === audio.AudioState.STATE_RELEASED) {
      console.info('Renderer released');
    } else {
      console.error('Renderer release failed.');
    }
  }
}

总结

AudioCapturer和AudioRenderer用于录制和播放录制PCM音频，适合有音频开发经验的开发者实现更灵活的录制和播放功能。

附件为Demo，实现了开始录制，停止录制，播放录音，暂停录音，停止录音功能。