我们的产品使用了微信小程序的webview的模式。 在接入讯飞的流式语音服务（https://www.xfyun.cn/doc/asr/voicedictation/API.htm）时，语音识别精度普遍不如预期。尤其是在语音输入较长时，识别精度的下降更为明显。这一点在其他用户中也会出现。进一步分析发现，发送给讯飞的原始pcm格式的音频其实有噪音，这可能是识别效果差的原因，但是噪音是如何来的不得而知。因为同样的代码在谷歌浏览器上就很正常，

如果有任何其他需要提供的信息，随时联系我，希望能够得到你们的帮助。

问题音频：https://lunar-fireplant-d5c.notion.site/80b77725a7c64ef98c55c2e19ed8224a

核心代码：

function mergeArrayBuffers(arrayBuffers: ArrayBuffer[]) {
  const totalLength = arrayBuffers.reduce(
    (acc, buffer) => acc + buffer.byteLength,
    0,
  );

  const mergedBuffer = new Uint8Array(totalLength);
  let offset = 0;

  arrayBuffers.forEach((buffer) => {
    mergedBuffer.set(new Uint8Array(buffer), offset);
    offset += buffer.byteLength;
  });

  return mergedBuffer.buffer;
}

function toBase64(buffer: ArrayBuffer) {
  const bytes = new Uint8Array(buffer);
  const len = bytes.byteLength;
  let binary = '';

  for (let i = 0; i < len; i++) {
    binary += String.fromCharCode(bytes[i]);
  }

  return window.btoa(binary);
}

export function startRecorder(options: RecorderOptions) {
  function parseResult(resultData: string) {
    const jsonData = JSON.parse(resultData);

    if (jsonData.data && jsonData.data.result) {
      const data = jsonData.data.result;
      const ws = data.ws;
      let str = '';

      for (let i = 0; i < ws.length; i++) {
        str = str + ws[i].cw[0].w;
      }

      // 开启wpgs会有此字段(前提：在控制台开通动态修正功能)
      // 取值为 "apd"时表示该片结果是追加到前面的最终结果；取值为"rpl" 时表示替换前面的部分结果，替换范围为rg字段
      if (data.pgs) {
        if (data.pgs === 'apd') {
          // 将resultTextTemp同步给resultText
          resultText = resultTextTemp;
        }

        // 将结果存储在resultTextTemp中
        resultTextTemp = resultText + str;
      } else {
        resultText = resultText + str;
      }

      options.onResult?.(resultTextTemp || resultText || '');
    }

    if (jsonData.code === 0 && jsonData.data.status === 2) {
      ws?.close();
    }

    if (jsonData.code !== 0) {
      ws?.close();
    }
  }

  function initWS() {
    ws = new WebSocket(options.url);

    ws.onopen = () => {
      ws!.send(
        JSON.stringify({
          common: {
            app_id: APPID,
          },
          business: {
            language: 'en_us', // en_us zh_cn
            domain: 'iat',
            accent: 'mandarin',
            vad_eos: 5000,
            dwa: 'wpgs',
          },
          data: {
            status: 0,
            format: 'audio/L16;rate=16000',
            encoding: 'raw',
          },
        }),
      );
    };

    ws.onerror = (err) => {
      ignoreStopCallback = true;
      options.onError(err);
    };

    ws.onmessage = (evt) => {
      parseResult(evt.data);
    };

    ws.onclose = () => {
      stopRecorder();
      status = 'CLOSED';
      console.log({ blobParts });

      if (!ignoreStopCallback) {
        options.onStop(
          new Blob(blobParts, {
            type: 'audio/ogg; codecs=opus',
          }),
        );
      }
    };
  }

  function stopRecorder() {
    if (stopped) {
      return;
    }

    clearTimeout(timer);
    stopped = true;
    recorder.stop();

    if (!ws) {
      options.onCancel?.();
    }
  }

  const timer = setTimeout(() => {
    stopRecorder();
    options.onTimeout?.();
  }, 60000);

  const startTime = Date.now();
  let blobParts: BlobPart[] = [];
  let queueFrames: Frame[] | null = [];
  let ws: WebSocket | null = null;
  let stopped = false;
  let resultText = '';
  let resultTextTemp = '';
  let status = 'CONNECTING';
  let ignoreStopCallback = false;

  recorder.onStart = () => {
    status = 'OPEN';
    options.onStart?.();
  };

  recorder.onStop = (audioBuffers: ArrayBuffer[]) => {
    blobParts = audioBuffers;
    clearTimeout(timer);

    if (options.minDuration && Date.now() - startTime < options.minDuration) {
      ignoreStopCallback = true;
      options.onTimeShortage?.();
    }

    // 因 recorder 实例是公共对象，需要手动清空内存
    recorder.onStart = null;
    recorder.onStop = null;
    recorder.onFrameRecorded = null;
  };

  recorder.onFrameRecorded = (frame: Frame) => {
    if (queueFrames) {
      queueFrames.push(frame);
    }

    if (ws?.readyState === WebSocket.OPEN) {
      const frames = queueFrames || [frame];

      if (queueFrames) {
        queueFrames = null;
      }

      for (const item of frames) {
        ws.send(
          JSON.stringify({
            data: {
              status: item.isLastFrame ? 2 : 1,
              format: 'audio/L16;rate=16000',
              encoding: 'raw',
              audio: toBase64(item.frameBuffer),
            },
          }),
        );
      }

      if (frame.isLastFrame) {
        status = 'CLOSING';
      }
    }
  };

  recorder
    .start({ sampleRate: 16000, frameSize: 1280 })
    .then(() => {
      if (stopped) {
        return;
      }

      // 如果从请求到响应的时间间隔超过 300ms 就认为是询问后授权，
      // 因为询问时，系统弹出授权框会中断页面交互，增加这个字段可以针对性做逻辑处理
      // ⚠️ 注意这个只是用响应延迟时间来判断，所以并不能保证 100% 正确
      const isPrompt = Date.now() - startTime > 300;

      if (isPrompt && options.cancelOnPrompt) {
        ignoreStopCallback = true;
        stopRecorder();

        return options.onCancel?.();
      }

      initWS();
    })
    .catch((err: any) => {
      if (stopped) {
        return;
      }

      clearTimeout(timer);
      options.onDenied?.(err);
    });

  return stopRecorder;
}