How do I get a snapshot still of a video in nodejs?


Question

I am trying to write a nodejs server that will take a time input (possibly part of url path) and then provide a still of the video frame at that time index as a jpeg picture.

I can do this easily in plain Javascript, but I cant see a way to do this in nodejs. I know I will probably need to use a canvas plugin like node-canvas to do the snapshot.

Any ideas welcome.

The following is how I do it in Javascript at the moment:

myjavascript.js

function capture(video, scaleFactor) {
    if(scaleFactor == null){
        scaleFactor = 1;
    }
    var w = video.videoWidth * scaleFactor;
    var h = video.videoHeight * scaleFactor;
    stdout("<br/> w: "+ w+ "<br/> h: "+ h);
    var canvas = document.createElement('canvas');
        canvas.width  = w;
        canvas.height = h;
    var ctx = canvas.getContext('2d');
        ctx.drawImage(video, 0, 0, w, h);
    return canvas;
}

function shoot(){
 var video  = document.getElementById("videoTag");
 var output = document.getElementById("output");
 var canvas = capture(video, 1);
 output.innerHTML = '';
 output.appendChild(canvas);
}

index.html

<html>
<head>
    <title>video snap</title>   
    <script type="text/javascript" src="myjavascript.js"></script>
</head>
<body>

<div id="video_container" >
        <video id="videoTag" width="640" height="360" autobuffer="" controls="true">
            <source src="frozenplanet.mp4" type="video/mp4">
            <source src="frozenplanet.ogv" type="video/ogg">
        </video>
</div>

<div id="output"></div>

</body>
</html>
1
16
1/10/2012 11:23:18 AM

Accepted Answer

node-fluent-ffmpeg has a nice takeScreenshots function.

var proc = new ffmpeg('/path/to/your_movie.avi')
  .takeScreenshots({
      count: 1,
      timemarks: [ '600' ] // number of seconds
    }, '/path/to/thumbnail/folder', function(err) {
    console.log('screenshots were saved')
  });
33
1/10/2012 1:58:40 PM

You can use the node-fluent-ffmpeg module for this. You'll need to install ffmpeg; on MacOS, install Homebrew then use the brew install ffmpeg command.

var ffmpeg = require('fluent-ffmpeg');

ffmpeg('/path/to/video.mp4')
  .on('end', function() {
    console.log('Screenshots taken');
  })
  .on('error', function(err) {
    console.error(err);
  })
  .screenshots({
    // Will take screenshots at 20%, 40%, 60% and 80% of the video
    count: 4,
    folder: '/path/to/output'
  });

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