mp4-mjpeg

A pure Javascript Node module to create video files from images

Install

npm install --save mp4-mjpeg

Usage

const mjpeg = require('mp4-mjpeg');
 
// starting a video file
mjpeg({ fileName: "path/to/my/file.mp4" })
    .then( (recorder) => {
 
        // append a JPEG image as a data URL to the video
        recorder.appendImageDataUrl( imageAsDataURL )
            .then( () => {
                // image added
            })
            .catch( (error) => {
                // something bad happened
            })
 
        // or if we have the image as a buffer
        recorder.appendImageBuffer( imageBuffer )
        // ...
 
        // all the images added ?
        // let finalize the MP4 file to make it playable
        recorder.finalize()
            .then( () => {
                // MP4 video file is ready
            })
            .catch( (error) {
                // too bad
            })
 
    })
    .catch( (error) => {
        // could not create the file
    })

API

• <module>(options): creates a video recorder. Options have properties:
  • fileName: the path to the output MP4 video file
  • reuseLastFrame: if an image is the same as the previous one, it does not take more data in the MP4 file (default true)
  • ignoreIdenticalFrames: if not 0 and the number of successive identical images has reached the parameter value, recording is put on hold until a different image is appended to the video (default '30`, 1 second)

The module function returns a Promise, not the actual recorder. To get the recorder:

    (require('mp4-mpjpeg'))(options)
        .then( (recorder) => {
            // the recorder can now be used to add images to the video
        });

• <recorder>.appendImageDataUrl(dataUrl): add an image to the video. This image is encoded in base64 prefixed with data:image/png;base64,, as what you get calling canvas.toDataURL('image/jpeg')
  The function returns a promise that is fulfilled when the image has been written

• <recorder>.appendImageBuffer(buffer): add an image to the video. The image is a plain buffer that you can obtain by reading a JPEG file
  The function returns a promise that is fulfilled when the image has been written

• <recorder>.finalize(): end the capturing process.
  The function returns a promise that is fulfilled when the video file is ready to be played

Limitations

• only MJPEG encoding is supported
• generated video files have no audio
• framerate is fixed to 30 fps
• there is no cropping or scaling capbility in this library, the images should be processed before being appended, or the generated MP4 file can be worked afterwards
• there is no queue for appending images: the developer using this library is in charge of the flow control, which can be done easily using the promise returned by appendXXX()
• all appended images should have the same size, or weird things may happen

About

This module has been written to cover a need on JoclyBoard: recording games being played in 3D. You can check JoclyBoard source code as an example of using this library