https://github.com/kevingodell/pipe2jpeg

Parse individual jpegs from an ffmpeg pipe when output codec(-c:v) is set to mjpeg and format(-f) is set to image2pipe, singlejpeg, mjpeg, or mpjeg.
https://github.com/kevingodell/pipe2jpeg

codec ffmpeg ffmpeg-pipe image2pipe jpeg mjpeg mpjpeg nodejs singlejpeg

Last synced: 3 months ago
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Parse individual jpegs from an ffmpeg pipe when output codec(-c:v) is set to mjpeg and format(-f) is set to image2pipe, singlejpeg, mjpeg, or mpjeg.

• Host: GitHub
• URL: https://github.com/kevingodell/pipe2jpeg
• Owner: kevinGodell
• License: mit
• Created: 2017-03-09T18:58:19.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2023-07-18T23:21:10.000Z (over 1 year ago)
• Last Synced: 2024-10-26T15:28:42.932Z (3 months ago)
• Topics: codec, ffmpeg, ffmpeg-pipe, image2pipe, jpeg, mjpeg, mpjpeg, nodejs, singlejpeg
• Language: JavaScript
• Homepage: https://kevingodell.github.io/pipe2jpeg/
• Size: 843 KB
• Stars: 13
• Watchers: 1
• Forks: 10
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Contributing: CONTRIBUTING.md
  • License: LICENSE

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README

        
# pipe2jpeg

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Parse individual jpegs from an FFmpeg pipe when the output codec(**-c:v**) is set to ***mjpeg*** and the format(**-f**) is set to ***image2pipe***, ***singlejpeg***, ***mjpeg***, or ***mpjpeg***.

### installation:

```

npm install pipe2jpeg --save

```

### usage:

The following example uses ffmpeg's **testsrc** to simulate a video input and generate 100 downscaled jpeg images at a rate of 1 per second. The jpeg images are piped in from ffmpeg's stdout and parsed for the start of image(SOI) and end of image(EOI) file markers. Using the default configuration, Pipe2Jpeg dispatches a "data" event that contains a complete jpeg image buffer. For more configuration options, view the [docs](https://kevingodell.github.io/pipe2jpeg/Pipe2Jpeg.html).

```javascript

const Pipe2Jpeg = require('pipe2jpeg');

const { spawn } = require('child_process');

let jpegCounter = 0;

const params = [

  /* log info to console */

  '-loglevel',

  'quiet',

  /* use an artificial video input */

  '-re',

  '-f',

  'lavfi',

  '-i',

  'testsrc=size=1920x1080:rate=15',

  /* set output flags */

  '-an',

  '-c:v',

  'mjpeg',

  '-pix_fmt',

  'yuvj420p',

  '-f',

  'image2pipe', // image2pipe, singlejpeg, mjpeg, or mpjpeg

  '-vf',

  'fps=1,scale=640:360',

  '-q',

  '2',

  '-frames',

  '100',

  'pipe:1'

];

const p2j = new Pipe2Jpeg();

p2j.on('data', (jpeg) => {

  console.log('received jpeg', ++jpegCounter);

});

const ffmpeg = spawn('ffmpeg', params, {stdio : ['ignore', 'pipe', 'ignore']});

ffmpeg.on('error', (error) => {

  console.log(error);

});

ffmpeg.on('exit', (code, signal) => {

  console.log('exit', code, signal);

});

ffmpeg.stdout.pipe(p2j);

```

Setting **readableObjectMode** to true will cause the output to be an object containing **list** and **totalLength** properties:

```javascript

const p2j = new Pipe2Jpeg({ readableObjectMode: true /* default false */ });

p2j.on('data', ({ list, totalLength }) => {

  // list is array of buffers comprising the jpeg

  console.log(Array.isArray(list), Buffer.isBuffer(list[0]));

  // totalLength is cumulative size of buffers in list

  console.log(Number.isInteger(totalLength));

  // list of buffers can be concatenated as needed

  const jpeg = Buffer.concat(list, totalLength);

});

// the list property will be set with the latest value

const list = p2j.list;

```

While **readableObjectMode** is set to true, **bufferConcat** can be set to true to cause the list of buffers to be concatenated into a single buffer:

```javascript

const p2j = new Pipe2Jpeg({ readableObjectMode: true /* default false */, bufferConcat: true /* default false */ });

p2j.on('data', ({ jpeg }) => {

  // jpeg is complete as a single buffer

  console.log(Buffer.isBuffer(jpeg));

});

// the jpeg property will be set with the latest value

const jpeg = p2j.jpeg;

```

If you have consistently sized jpegs, then setting **byteOffset** to a number approximately 75% of the expected size can minimize the time searching for EOI and result in a small performance gain:

```javascript

const p2j = new Pipe2Jpeg({ byteOffset: 10000 /* default 200 */ });

```

While **readableObjectMode** is set to false or **bufferConcat** is set to true, an experimental buffer pool can be used to reduce garbage collection and increase performance:

```javascript

const p2j = new Pipe2Jpeg({ pool: 1 /* default 0 */ });

```

### testing:

Clone the repository

```

git clone https://github.com/kevinGodell/pipe2jpeg.git

```

Change into the directory

```

cd pipe2jpeg

```

Initialize with npm

```

npm install

```

Start the tests

```

npm test

```