streaming webcam upload

streaming-webcam-upload.js

const s3 = new AWS.S3();
const BUCKET = 'multipart-upload-test';
const FILENAME = `test-${Math.random()}.webm`;

const logSize = size => {
  console.log(`current size: ${totalSize / (1024*1024)}mb`);
};

const createUpload = () => new Promise((resolve, reject) => {
  const options = { Bucket: BUCKET, Key: FILENAME };
  const cb = (mpErr, multipart) => {
    if (mpErr) { return reject(mpErr) }
    resolve(multipart);
  };

  s3.createMultipartUpload(options, cb);
});

const uploadPart = (blob, partNumber, multipart) => new Promise(resolve => {
  s3.uploadPart({
    Body: blob,
    Bucket: BUCKET,
    Key: FILENAME,
    PartNumber: String(partNumber),
    UploadId: multipart.UploadId
  }, (err, data) => {
    resolve(data);
  });
});

const completeUpload = (multipart, multipartMap) => new Promise(resolve => {
  s3.completeMultipartUpload({
    Bucket: BUCKET,
    Key: FILENAME,
    MultipartUpload: multipartMap,
    UploadId: multipart.UploadId
  }, resolve);
});

const createRecorder = stream => {
  const recorder = new MediaRecorder(stream);

  const readableStream = new ReadableStream({
    start(controller) {
      recorder.ondataavailable = ({data}) => controller.enqueue(data);
      recorder.onstop = () => controller.close();
    },

    cancel() {
      recorder.stop();
    }
  });

  return {recorder, readableStream}
};

const processStream = async (readableStream, multipart) => {
  let partNumber = 1;
  let totalSize = 0;
  let multipartMap = { Parts: [] };

  for await (const data of streamAsyncIterator(readableStream)) {
    const {ETag} = await uploadPart(data, partNumber, multipart);
    multipartMap.Parts[partNumber-1] = {ETag, PartNumber: partNumber};
    totalSize += data.size;
    partNumber += 1;
    logSize(totalSize);
  }

  const result = await completeUpload(multipart, multipartMap);
  console.log('done', result)
};

const run = async () => {
  const {recorder, readableStream} = await getWebcamStream().then(createRecorder);
  const multipart = await createUpload();

  processStream(readableStream, multipart);
  recorder.start(1000);
  setTimeout(() => recorder.stop(), 30000);
};

run();