EpicSoul/components/GPT/utils/pcm-player.js

// utils/pcm-player.js
export default class PCMPlayer {
  constructor(options) {
    this.queue = [];
    this._options = options
    this.AllTexts = [];
    this.audioCtx = null;
    this.startTime = 0;
    this._t = null
  }
  feed(data) {
    if (!this.audioCtx) {
      this.audioCtx = wx.createWebAudioContext();
    }
    this.playPCM(data);
  }

  playPCM(pcmBuffer, sampleRate = 16000) {
    const length = pcmBuffer.byteLength / 2; // 16-bit = 2 bytes per sample
    const audioBuffer = this.audioCtx.createBuffer(1, length, sampleRate);
    const channelData = audioBuffer.getChannelData(0); // Float32Array
    const view = new DataView(pcmBuffer);

    // 将 16-bit PCM 转换为 Float32 [-1, 1]
    for (let i = 0; i < length; i++) {
      const sample = view.getInt16(i * 2, true); // little-endian
      channelData[i] = sample / 0x8000; // convert to [-1, 1]
    }

    this.queue.push(audioBuffer);
    if (!this.isPlaying) {
      // 开始播放
      this.startTime = this.audioCtx.currentTime ?? 0;
      this.playNext();
      this.isPlaying = true;
      setTimeout(() => {
        this.syncLoop();      
      });
      
    }
  }
  // 监听音频播放进度
  syncLoop() {
    const loop = () => {
      const now = this.audioCtx.currentTime - this.startTime;
      // 找当前字幕
      const index = this.AllTexts.findIndex(
        (s) => now >= s.beginTime && now < s.endTime
      );
      if (index > -1) {
        const obj = this.AllTexts[index];
        if (this.AllTexts.length == 1) {
          // 最后一条数据
          obj.is_final = true
        }
        const tmp = this.AllTexts.shift();
        this._options.onPlay && this._options.onPlay(tmp);
        if (!this.AllTexts.length) {
          clearTimeout(this._t);
          return
        }
      }
      if (!this.AllTexts.length) {
        this._t = setTimeout(loop, 16);
      } else {
        if (now < this.AllTexts[this.AllTexts.length - 1].endTime) {
          this._t = setTimeout(loop, 16);
        } else {
          // 结束
          clearTimeout(this._t);
          console.log('语音播放结束')
          this.destroy()
        }
      }
    };
    loop();
  }

  playNext() {
    if (this.queue.length === 0) {
      // 结束
      this.isPlaying = true;
      return;
    }
    this.isPlaying = true;
    const source = this.audioCtx.createBufferSource();
    source.buffer = this.queue.shift();
    source.connect(this.audioCtx.destination);
    source.start();
    source.onended = () => {
      setTimeout(() => {
        this.playNext();
      });
    };
  }

  // 增加文字
  addText(res) {
    if (res.result && res.result.subtitles && res.result.subtitles.length) {
    const tmpText = res.result.subtitles.map((it) => {
      return {
        ...it,
        content: it.text,
        beginTime: it.beginTime / 1000,
        endTime: it.endTime / 1000,
        request_id: res.requestId,
        sessionId: res.sessionId
      };
    });
    this.AllTexts = [...this.AllTexts, ...tmpText];
    }
  }

  close() {
    this.isPlaying = false;
    this.audioCtx.close();
  }
  destroy() {
    this.queue = [];
    this.isPlaying = false;
    this.audioCtx && this.audioCtx.close();
    this.audioCtx = null;
    this.AllTexts = [];
    this.startTime = 0;
    this._options.onAudioEnd && this._options.onAudioEnd()
  }
}