libqrv

libqrv

libqrv is a node module that is used to encode data into video streams. Specifically it does this by transforming data into QR codes, and stitching the multiple frames together into a single video file.

Example

By running the yarn.lock file in the examples directory through convertFile, the video below is produced.

Installation

$ yarn install libqrv

Basic Usage

convertFile

convertFile( existingFile [, newFilePath] , cb )

Converts a file into a mp4 video stream of QR codes that contain the base64 encoded data. If newFilePath is not specified .mp4 is added to the file path passed in.

const { convertFile } = require( "libqrv" );

convertFile( "./some/file.txt", "./another/location/output.mp4", ( err ) => {

	// err is null unless there is an error
	if( err ){
		return console.log( "Couldn't convert the file.. " + err );
	}

	// "./another/location/output.mp4" exists
} );

const { convertFile } = require( "libqrv" );

convertFile( "./some/file.txt", ( err ) => {

	if( err ){
		return console.log( "Couldn't convert the file.. " + err );
	}

	// if err is not null, and no newFIlePath has been specified
	// existingFile + ".mp4" is assumed.

	// "./some/file.txt.mp4" exists
	
} );

Directly Using the Library

The LibQRV library itself provides some customization. There are a lot of opportunities that exist to expose more configuration, and functionality.

Usage

const { LibQRV } = require( "libqrv" );

const config = {
	debug: true
};

new LibQRV( config, ( err, libqrv ) => {

	// libqrv can be used here

	libqrv.on( "readableStreamComplete", ( details ) => {
		/*
		details = {
			filename: "yarn.lock",
			outputPath: "/var/folders/qr/z123...../T/tmp-..../yarn.lock.mp4"
		}
		*/


		// Let's ensure that we clean up any resources
		libqrv.destroy( ( err ) => {
			if( err ){
				console.log( "Couldn't clean up resources: " + err );
				return;
			}
			console.log( "Cleaned up resources. Goodbye." );
		} );
	} );

	libqrv.queueReadableStream( fs.createReadStream( "./yarn.lock" ), ( err ) => {
		if( err ){
			console.log( "Couldn't queue readable stream: " + err );
			return;
		}

		// Readable stream has been queued.

		// When complete "readableStreamComplete" will be emitted.
	} );
} );

Default Options

{
  "debug": false,
  "outputDirectory": "/tmp/tmp-34.........", // geneated by tmp
  "qr": {
    "width": 240,
    "scale": 1,
    "margin": 0,
    "errorCorrectionLevel": "low"
  },
  "video": {
    "output": {
      "framerate": 25
    },
    "input": {
      "framerate": 1
    }
  }
}

Options to constructor

Option Name	Default Value	Description
outputDirectory	Dynamically Generated ( uses tmp )	The directory where the output .mp4 will be placed.
debug	false	Whether or not to emit debug events
qr	See QR Options	Configuration that relates to QR Code generation
video	See Video Options	Configuration that relates to the video generation

QR Options

Option Name	Default Value	Description
width	240	The width of the QR code frame that is generated
scale	1	The number of pixels that are used per "block" to make up the QR code
margin	0	The amount of blank space that is kept around the QR code. Synonymous with HTML padding
errorCorrectionLevel	"low"	How much error correction is used in the QR code.

Video Options

Option Name	Default Value	Description
input.framerate	1	The framerate relating to the QR code images. Per second
output.framerate	25	The output .mp4 video framerate. Per second

Constructor LibQRV uses a configuration object that is passed into the constructor. Additionally, the constructor takes a callback that is called with cb( err, instance ) where err should be null, and instance is the newly created instance of LibQRV.

Help Wanted

If you find this module or repository useful, please consider making a pull request to it.

Running tests

$ yarn run test

yarn run v1.3.2
$ ./node_modules/mocha/bin/mocha -t 60000


  Base
    ✓ LibQRV is a function
    Validations
      ✓ Fails if an invalid config is passed in
    Basic operation
      ✓ Constructor returns sane object in callback
      ✓ Emits a 'readableStreamComplete' event when finished encoding a readable stream. (8492ms)
    convertFile operation
      ✓ Works when we specify a filename (10250ms)
      ✓ Works when we don't specify a filename (8534ms)


  6 passing (27s)

✨  Done in 28.27s.

License

MIT