webm-duration-fix/README.md

based on ts-ebml and support large file(than 2GB) and optimize memory usage during repair

# webm-duration-fix

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](https://bugs.chromium.org/p/chromium/issues/detail?id=642012)

## Features

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

## Demo

[Browser Demo](https://github.com/buynao/mediaRecorder-demo)

[Electron/NodeJs Demo](https://github.com/buynao/electron-recorder-app)

## Install

```js
npm i webm-duration-fix -S
// or
yarn add webm-duration-fix 
```

## Usage

```typescript
import fixWebmDuration from 'webm-duration-fix';

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

### v1.0.4 (Apr 4, 2022)

- compatible fix for ebmlID increase

### v1.0.3（Dec 15, 2021）

- fix browser apply buffer error