extendable-media-recorder-wav-encoder-worker/build/es2019/factories/encode.js

The worker which is used by the extendable-media-recorder-wav-encoder package.

export const createEncode = (computeNumberOfSamples, encodeHeader) => {
  return (channelDataArrays, part, bitRate, sampleRate) => {
    const bytesPerSample = bitRate >> 3;
    const headerSize = part === "subsequent" ? 0 : 44;
    const numberOfChannels = channelDataArrays.length;
    const numberOfSamples = computeNumberOfSamples(channelDataArrays[0]);
    const arrayBuffer = new ArrayBuffer(numberOfSamples * numberOfChannels * bytesPerSample + headerSize);
    const dataView = new DataView(arrayBuffer);
    if (part !== "subsequent") {
      encodeHeader(dataView, bitRate, numberOfChannels, part === "complete" ? numberOfSamples : Number.POSITIVE_INFINITY, sampleRate);
    }
    channelDataArrays.forEach((channel, index) => {
      let offset = headerSize + index * bytesPerSample;
      channel.forEach((channelDataArray) => {
        const length = channelDataArray.length;
        for (let i = 0; i < length; i += 1) {
          const value = channelDataArray[i];
          dataView.setInt16(offset, value < 0 ? Math.max(-1, value) * 32768 : Math.min(1, value) * 32767, true);
          offset += numberOfChannels * bytesPerSample;
        }
      });
    });
    return [arrayBuffer];
  };
};