mp4-mjpeg v0.0.2

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