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jMuxer - a simple javascript mp4 muxer that works in both browser and node environment.

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jMuxer - a simple javascript mp4 muxer that works in both browser and node environment. It is communication protocol agnostic and it is intended to play media files on the browser with the help of the media source extension. It also can export mp4 on the node environment. It expects raw H264 video data and/or AAC audio data in ADTS container as an input.

Live Demo

Click here to view a working demo

Click here to play a h264 file online

How to use?

a distribution version is available on dist folder.


var jmuxer = new JMuxer(option);

Available options are:

node - String ID of a video tag / Reference of the HTMLVideoElement. Required field for browsers.

mode - Available values are: both, video and audio. Default is both

flushingTime - Buffer flushing time in seconds. Default value is 1500 miliseconds.

clearBuffer - true/false. Either it will clear played media buffer automatically or not. Default is true.

fps - Optional value. Frame rate of the video if it is known/fixed value. It will be used to find frame duration if chunk duration is not available with provided media data.

onReady - function. Will be called once MSE is ready.

debug - true/false. Will print debug log in browser console. Default is false.

Complete example:


Media dataObject may have folloiwng properties:

video - h264 buffer

audio - AAC buffer

duration - duration in miliseconds of the provided chunk. If duration is not provided, it will calculate frame duration wtih the provided frame rate (fps).

ES6 Example:

Install module through

npm install --save jmuxer
import JMuxer from 'jmuxer';

const jmuxer = new JMuxer({ node: 'player', debug: true });

/* Now feed media data using feed method. audio and video is buffer data and duration is in miliseconds */ jmuxer.feed({ audio: audio, video: video, duration: duration });

Node Example:

Install module through

npm install --save-dev jmuxer
const JMuxer = require('jmuxer');
const jmuxer = new JMuxer({
    debug: true

/* Stream in Object mode. Please check the example file for more details */ let h264_feeder = getFeederStreamSomehow(); let http_or_ws_or_any = getWritterStreamSomehow(); h264_feeder.pipe(jmuxer.createStream()).pipe(http_or_ws_or_any);

Available Methods

| Name | Parameter | Remark | | ------------- |:-------------:| -----:| | feed | data object | object properites may have audio, video and duration. At least one media property i.e audio or video must be provided. If no duration is provided, it will calculate duration based on fps value | | createStream | - | Get a writeable stream to feed buffer. Available on NodeJS only | | destroy | - | Destroy the jmuxer instance and release the resources |


compatible with browsers supporting MSE with 'video/MP4. it is supported on:

  • Chrome for Android 34+
  • Chrome for Desktop 34+
  • Firefox for Android 41+
  • Firefox for Desktop 42+
  • IE11+ for Windows 8.1+
  • Edge for Windows 10+
  • Opera for Desktop
  • Safari for Mac 8+

Demo Server and player example

A simple node server and some demo media data are available in the example directory. In the example, each chunk/packet is consist of 4 bytes of header and the payload following the header. The first two bytes of the header contain the chunk duration and remaining two bytes contain the audio data length. Packet format is shown in the image below:

Packet format

| 2 bytes | 2 bytes | | | |-------------|-----------------|----------------|-----------------| |Duration (ms)|Audio Data Length|Audio Data (AAC)|Video Data (H264)|

A step guideline to obtain above the packet format from your mp4 file using ffmpeg: 1. Spliting video into 2 seconds chunks:

ffmpeg -i input.mp4 -c copy -map 0 -segment_time 2 -f segment %03d.mp4
1. Extracting h264 for all chunks:
for f in *.mp4; do ffmpeg -i "$f" -vcodec copy -an -bsf:v h264_mp4toannexb "${f:0:3}.h264"; done
1. Extracting audio for all chunks:
for f in *.mp4; do ffmpeg -i "$f" -acodec copy -vn "${f:0:3}.aac"; done
1. Extracting duration for all chunks:
for f in *.mp4; do ffprobe "$f" -show_format 2>&1 | sed -n 's/duration=//p'; done


How to run example?

Demo files are available in example directory. For running the example, first run the node server by following command:

cd example

node server.js

then, visit example/index.html page using any webserver.

Player Example for raw h264 only

Assuming you are still in

directory. Now run followngs:

node h264.js

then, visit example/h264.html page using any webserver.

How to build?

A distribution version is available inside dist directory. However, if you need to build, you can do as follows:

  1. git clone
  2. cd jmuxer
  3. npm install
  4. npm run build OR npm run pro


If the project helps you, buy me a cup of coffee!


Proudly inspired by hls.js, rtsp player - for sponsoring the adaptation of jMuxer for Node.js

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