webm-duration-fix-buffer

based on ts-ebml and support large file，optimize memory usage during repair

Introduction

When we use webm video generated by getUserMedia, MediaRecorder and other APIs, we will find that the final webm is not able to drag the progress bar. Unless we use FFmpeg to convert webm to other format video files, or wait for the webm video to finish playing, then we can drag it.

Here is the community discussion Issue 642012

Features

• Compatible with node & browsers
• Fix oversized files with low memory usage

Demo

Browser Demo

Electron/NodeJs Demo

Install

npm i webm-duration-fix-buffer -S
// or
yarn add webm-duration-fix-buffer

Usage

import fixWebmDuration from "webm-duration-fix-buffer";

const mimeType = "video/webm;codecs=vp9";
const blobSlice: BlobPart[] = [];

mediaRecorder = new MediaRecorder(stream, {
  mimeType,
});

mediaRecorder.ondataavailable = (event: BlobEvent) => {
  blobSlice.push(event.data);
};

mediaRecorder.onstop = async () => {
  // fix blob, support fix webm file larger than 2GB
  const fixBlob = await fixWebmDuration(
    new Blob([...blobSlice], { type: mimeType })
  );
  const fileWriteStream = fs.createWriteStream(inputPath);
  const blobReadstream = fixBlob.stream();
  const blobReader = blobReadstream.getReader();

  while (true) {
    let { done, value } = await blobReader.read();
    if (done) {
      console.log("write done.");
      fileWriteStream.close();
      break;
    }
    fileWriteStream.write(value);
    value = null;
  }
  blobSlice = [];
};

Changelog

• fix RangeError: The value of "byteLength" is out of range. It must be >= 1 and <= 6. Received 7

• compatible fix for ebmlID increase

• fix browser apply buffer error