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