# 快速多次点击按键，声音播放有卡顿的情况

#### 问题现象

在乐器模拟类应用中，点击不同的按键会发出不同的声音，当快速多次点击按键时，存在声音播放卡顿的情况。

#### 背景知识

SoundPool：提供短音频的播放能力，应用只需要提供音频资源来源，不负责数据解析和解码就可达到播放效果。其提供的接口函数如下：

| 函数名 | 描述 |
| --- | --- |
| load | 加载音频资源 |
| play | 播放音频资源 |
| stop | 停止播放音频资源 |
| setVolume | 设置音频流播放音量 |
| unload | 卸载音频资源 |

#### 问题定位

1.  在日志中搜索SoundPool::Play|SoundPool::SetVolume，查看点击两次按键时应用播放音频资源、设置播放音量的情况，如下可以看到应用播放音频资源两次，多次设置播放音量，由于播放音量变化无规律，变大又变小，导致音量忽高忽低，出现卡顿的情况。
    
    ```
    07-18 15:48:58.598   3033-6630    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::Play soundID::1 ,priority::1
    07-18 15:48:58.600   3033-6630    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::Play streamID::1
    07-18 15:48:58.631   3033-6631    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.950000, rightVolume:0.950000
    07-18 15:48:58.662   3033-6269    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.900000, rightVolume:0.900000
    07-18 15:48:58.693   3033-6617    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.850000, rightVolume:0.850000
    07-18 15:48:58.724   3033-6618    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.800000, rightVolume:0.800000
    07-18 15:48:58.753   3033-4149    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.750000, rightVolume:0.750000
    07-18 15:48:58.766   3033-6622    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::Play soundID::1 ,priority::1
    07-18 15:48:58.766   3033-6622    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::Play streamID::1
    07-18 15:48:58.783   3033-6619    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.700000, rightVolume:0.700000
    07-18 15:48:58.798   3033-6621    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.950000, rightVolume:0.950000
    07-18 15:48:58.814   3033-6623    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.650000, rightVolume:0.650000
    07-18 15:48:58.830   3033-6620    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.900000, rightVolume:0.900000
    07-18 15:48:58.845   3033-6624    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.600000, rightVolume:0.600000
    07-18 15:48:58.859   3033-6625    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.850000, rightVolume:0.850000
    07-18 15:48:58.875   3033-6628    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.550000, rightVolume:0.550000
    07-18 15:48:58.889   3033-6629    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.800000, rightVolume:0.800000
    07-18 15:48:58.905   3033-6630    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.500000, rightVolume:0.500000
    07-18 15:48:58.920   3033-6631    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.750000, rightVolume:0.750000
    07-18 15:48:58.935   3033-6269    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.450000, rightVolume:0.450000
    07-18 15:48:58.951   3033-6617    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.700000, rightVolume:0.700000
    07-18 15:48:58.966   3033-6618    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.400000, rightVolume:0.400000
    07-18 15:48:58.982   3033-4149    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.650000, rightVolume:0.650000
    07-18 15:48:58.997   3033-6622    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.350000, rightVolume:0.350000
    07-18 15:48:59.013   3033-6619    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.600000, rightVolume:0.600000
    07-18 15:48:59.028   3033-6621    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.300000, rightVolume:0.300000
    07-18 15:48:59.045   3033-6623    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.550000, rightVolume:0.550000
    07-18 15:48:59.060   3033-6620    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.250000, rightVolume:0.250000
    07-18 15:48:59.075   3033-6624    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.500000, rightVolume:0.500000
    07-18 15:48:59.089   3033-6625    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.200000, rightVolume:0.200000
    07-18 15:48:59.106   3033-6628    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.450000, rightVolume:0.450000
    07-18 15:48:59.120   3033-6629    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.150000, rightVolume:0.150000
    07-18 15:48:59.136   3033-6630    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.400000, rightVolume:0.400000
    07-18 15:48:59.152   3033-6631    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.100000, rightVolume:0.100000
    07-18 15:48:59.167   3033-6269    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.350000, rightVolume:0.350000
    07-18 15:48:59.182   3033-6617    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.050000, rightVolume:0.050000
    07-18 15:48:59.196   3033-6618    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.300000, rightVolume:0.300000
    07-18 15:48:59.228   3033-6622    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.250000, rightVolume:0.250000
    07-18 15:48:59.258   3033-6619    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.200000, rightVolume:0.200000
    07-18 15:48:59.287   3033-6621    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.150000, rightVolume:0.150000
    07-18 15:48:59.318   3033-6623    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.100000, rightVolume:0.100000
    07-18 15:48:59.349   3033-6620    C02B2F/com.exa...ion/SoundPool com.examp...lication  I     SoundPool::SetVolume streamID:1, leftVolume:0.050000, rightVolume:0.050000
    ```
    
2.  根据上述日志情况可在代码中搜索setVolume确认是否存在多次设置音量的情况，从以下示例可看到在播放音频资源时有调用setInterval设置的重复定时任务，设置不同的音量值，当音频未播放完时点击按钮会设置较高的音量值，引起音量跳变。
    
    ```
    import { media } from '@kit.MediaKit';
    import { audio } from '@kit.AudioKit';
    import { BusinessError } from '@kit.BasicServicesKit';
    import { common } from '@kit.AbilityKit';
    
    
    class VolumeController {
      streamId: number = 0;
      soundId: number = 0;
      duration: number = 0;
      interval: number = 0;
      volume: number = 0;
      soundPool : media.SoundPool | undefined = undefined;
      intervalNum: number = 0;
      volumeUnit: number = 0;
    
    
      constructor(streamId: number, soundId: number, duration: number, interval: number,
        soundPool : media.SoundPool | undefined = undefined, volume: number) {
        this.streamId = streamId;
        this.soundId = soundId;
        this.duration = duration;
        this.interval = interval;
        this.volume = volume;
        this.volumeUnit = volume / ( duration / interval );
        this.soundPool = soundPool;
      }
    
    
      start() {
        this.intervalNum = setInterval(() => {
          this.duration = this.duration - this.interval;
          if (this.duration <= 0) {
            // 当播放结束时，停止播放并清除定时器
            this.soundPool?.stop(this.streamId);
            clearInterval(this.intervalNum);
          } else {
            // 每次将音量减少一个volumeUnit单位
            this.volume = this.volume - this.volumeUnit;
            this.soundPool?.setVolume(this.streamId, this.volume, this.volume);
          }
        }, this.interval);
      }
    
    
      stop() {
        clearInterval(this.intervalNum);
      }
    }
    
    
    @Entry
    @Component
    struct VolumeControllerPage {
      soundPool : media.SoundPool | undefined = undefined;
      soundId: number = 0;
      streamId: number = 0;
      context = this.getUIContext().getHostContext() as common.UIAbilityContext;
      playParameters: media.PlayParameters = {
        loop: 0, // 循环3次。
        rate: audio.AudioRendererRate.RENDER_RATE_NORMAL, // 正常倍速。
        leftVolume: 0.5,
        rightVolume: 0.5,
        priority: 1, // 最低优先级。
      };
      volumeController?: VolumeController;
    
    
      aboutToAppear(): void {
        media.createSoundPool(8, {
          usage: audio.StreamUsage.STREAM_USAGE_MUSIC,
          rendererFlags: 0
        }, async (error: BusinessError, soundPool_: media.SoundPool) => {
          if (error) {
            return;
          }
          this.soundPool = soundPool_;
          let fileDescriptor = await this.context.resourceManager.getRawFd('50.AAC'); // 50.AAC为测试的音频文件，可替换
          this.soundPool.load(fileDescriptor.fd, fileDescriptor.offset, fileDescriptor.length,
            (error: BusinessError, soundId_: number) => {
            if (error) {
              console.error(`Failed to load soundPool: errCode is ${error.code}, errMessage is ${error.message}`);
            } else {
              this.soundId = soundId_;
              console.info(`Succeeded in loading soundId: ${soundId_}`);
            }
          });
        });
      }
    
    
      build() {
        Column({ space: 15 }) {
          Button('播放声音')
            .onClick(() => {
              // 点击播放
              this.soundPool?.play(this.soundId, this.playParameters, (error: BusinessError, streamId: number) => {
                if (error) {
                  console.error('play error');
                  return;
                }
                console.info(`play streamId: ${streamId}`);
                this.streamId = streamId;
                this.volumeController = new VolumeController(this.streamId, this.soundId, 600, 30, this.soundPool, 1);
                this.volumeController.start();
              });
            })
        }
        .height('100%')
        .width('100%')
        .justifyContent(FlexAlign.Center)
      }
    }
    ```
    

#### 分析结论

快速点击按键播放音频资源时，有多次设置播放音量，播放音量变化无规律，变大又变小，导致音量忽高忽低，出现卡顿的情况。

#### 修改建议

1.  使用音量有变化的音频资源，避免多次修改音量。
2.  缩短修改音量的定时器任务的总时长，在定时器未执行完成前，不播放新的音频资源。
    
    ```
    import { media } from '@kit.MediaKit';
    import { audio } from '@kit.AudioKit';
    import { BusinessError } from '@kit.BasicServicesKit';
    import { common } from '@kit.AbilityKit';
    
    
    class VolumeController {
      streamId: number = 0;
      soundId: number = 0;
      duration: number = 0;
      interval: number = 0;
      volume: number = 0;
      soundPool: media.SoundPool | undefined = undefined;
      intervalNum: number = 0;
      volumeUnit: number = 0;
      isStop: boolean = true;
    
    
      constructor(streamId: number, soundId: number, duration: number, interval: number,
        soundPool: media.SoundPool | undefined = undefined, volume: number) {
        this.streamId = streamId;
        this.soundId = soundId;
        this.duration = duration;
        this.interval = interval;
        this.volume = volume;
        this.volumeUnit = volume / (duration / interval);
        this.soundPool = soundPool;
      }
    
    
      start() {
        this.isStop = false;
        this.intervalNum = setInterval(() => {
          this.duration = this.duration - this.interval;
          if (this.duration <= 0) {
            // 当播放结束时，停止播放并清除定时器
            this.soundPool?.stop(this.streamId);
            clearInterval(this.intervalNum);
            this.isStop = true;
          } else {
            // 每次将音量减少一个volumeUnit单位
            this.volume = this.volume - this.volumeUnit;
            this.soundPool?.setVolume(this.streamId, this.volume, this.volume);
          }
        }, this.interval);
      }
    
    
      stop() {
        this.isStop = true;
        clearInterval(this.intervalNum);
      }
    }
    
    
    @Entry
    @Component
    struct VolumeControllerPage {
      soundPool: media.SoundPool | undefined = undefined;
      soundId: number = 0;
      streamId: number = 0;
      context = this.getUIContext().getHostContext() as common.UIAbilityContext;
      playParameters: media.PlayParameters = {
        loop: 0, // 循环3次。
        rate: audio.AudioRendererRate.RENDER_RATE_NORMAL, // 正常倍速。
        leftVolume: 0.5,
        rightVolume: 0.5,
        priority: 1, // 最低优先级。
      };
      volumeController?: VolumeController;
    
    
      aboutToAppear(): void {
        media.createSoundPool(8, {
          usage: audio.StreamUsage.STREAM_USAGE_MUSIC,
          rendererFlags: 0
        }, async (error: BusinessError, soundPool_: media.SoundPool) => {
          if (error) {
            return;
          }
          this.soundPool = soundPool_;
          let fileDescriptor = await this.context.resourceManager.getRawFd('50.AAC'); // 50.AAC为测试的音频文件，可替换
          this.soundPool.load(fileDescriptor.fd, fileDescriptor.offset, fileDescriptor.length,
            (error: BusinessError, soundId_: number) => {
              if (error) {
                console.error(`Failed to load soundPool: errCode is ${error.code}, errMessage is ${error.message}`);
              } else {
                this.soundId = soundId_;
                console.info(`Succeeded in loading soundId: ${soundId_}`);
              }
            });
        });
      }
    
    
      build() {
        Column({ space: 15 }) {
          Button('播放声音')
            .onClick(() => {
              // 使用isStop变量，控制定时器未执行完成前，不播放新的音频资源
              if (!this.volumeController || this.volumeController?.isStop) {
                this.soundPool?.play(this.soundId, this.playParameters, (error: BusinessError, streamId: number) => {
                  if (error) {
                    console.error('play error');
                    return;
                  }
                  console.info(`play streamId: ${streamId}}`);
                  this.streamId = streamId;
                  this.volumeController = new VolumeController(this.streamId, this.soundId, 600, 30, this.soundPool, 1);
                  this.volumeController.start();
                });
              }
            })
        }
        .height('100%')
        .width('100%')
        .justifyContent(FlexAlign.Center)
      }
    }
    ```