Camera: implement "streaming" video (frame captures via piped/date ev…

…ents) Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
tessel · Mar 17, 2016 · 31ffce0 · 31ffce0
1 parent 5b17ca9
commit 31ffce0
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Showing 5 changed files with 200 additions and 104 deletions.
diff --git a/lib/camera.js b/lib/camera.js
@@ -4,14 +4,17 @@ var fs = require('fs');
 var Emitter = require('events').EventEmitter;
 var Readable = require('stream').Readable;
 
-var platform = process.platform;
-var isDarwin = platform === 'darwin';
-var stub = {
-  capture: function() {}
-};
-
 var priv = new Map();
 
+function scale(value, fromLow, fromHigh, toLow, toHigh) {
+  return (value - fromLow) * (toHigh - toLow) /
+    (fromHigh - fromLow) + toLow;
+}
+
+function constrain(value, lower, upper) {
+  return Math.min(upper, Math.max(lower, value));
+}
+
 function CaptureStream() {
   Readable.call(this);
   this._read = function() {};
@@ -23,80 +26,166 @@ CaptureStream.prototype = Object.create(Readable.prototype, {
   }
 });
 
-function FSWebcam(options) {
-  this.path = options.path;
-  this.quality = options.quality;
-  this.width = options.width;
-  this.height = options.height;
-}
-
-FSWebcam.prototype.capture = function(callback) {
-  // TODO: Stream this directly to capture stream/callback
-  var fswebcam = cp.spawn('fswebcam', [
-    '-i', '0', '-d', 'v4l2:' + this.path, '--no-banner', '--jpeg', this.quality, '--save', '/tmp/capture.jpg'
-  ]);
-
-  fswebcam.on('close', function(code) {
-    var error = code === 0 ? null : error;
-
-    if (error) {
-      callback(error);
-    } else {
-      fs.readFile('/tmp/capture.jpg', callback);
-    }
-  });
-};
-
 function Camera(options) {
   Emitter.call(this);
 
-  var device = isDarwin ?
-    (global.IS_TEST_ENV ? stub : require('bindings')('capture.node')) :
-    new FSWebcam(options);
+  options = options || {};
+
+  if (typeof options.stream === 'undefined') {
+    options.stream = false;
+  }
 
-  priv.set(this, {
-    device: device,
+  if (typeof options.pipe === 'undefined') {
+    options.pipe = true;
+  }
+
+  var state = {
+    isStreaming: false,
+    stream: options.stream,
+    pipe: options.pipe,
+    path: options.path,
+    quality: constrain(options.quality, 0, 1),
     width: options.width,
     height: options.height,
-  });
+    process: null,
+  };
+
+  priv.set(this, state);
 }
 
 Camera.prototype = Object.create(Emitter.prototype, {
   constructor: {
     value: Camera
+  },
+  isStreaming: {
+    get: function() {
+      return priv.get(this).isStreaming;
+    }
   }
 });
 
-Camera.prototype.capture = function() {
+Camera.prototype.stop = function() {
+  var state = priv.get(this);
+  state.process.kill('SIGTERM');
+  state.process = null;
+};
+
+Camera.prototype.capture = function(options) {
   var state = priv.get(this);
   var cs = new CaptureStream();
+  var buffer;
 
-  cs.on('data', function(result) {
-    this.emit('data', result);
-  }.bind(this));
+  options = options || {};
 
-  cs.on('end', function(result) {
-    this.emit('end', result);
-  }.bind(this));
+  if (typeof options.pipe !== 'undefined') {
+    state.pipe = options.pipe;
+  }
 
-  if (isDarwin) {
-    setImmediate(function() {
-      cs.push(state.device.capture());
-      cs.push(null);
-    });
+  if (typeof options.stream !== 'undefined') {
+    state.stream = options.stream;
+  }
+
+  var args = [
+    // Overwrite: yes
+    '-y',
+    // Logging: fatal
+    '-v', 'fatal',
+    '-r', '30',
+    '-i', state.path,
+    '-s', `${state.width}x${state.height}`,
+    '-q:v', scale(state.quality, 0, 1, 30, 1),
+  ];
+
+  if (state.stream) {
+    args.push(
+      // '-r', '30',
+      // '-i', '/dev/video0',
+      // '-y',
+      // '-s', '320x240',
+      '-f', 'MJPEG',
+      // '-f', 'h264',
+      '-b:v', '128k',
+      '-r', '30',
+      'pipe:1'
+    );
   } else {
-    state.device.capture(function(error, data) {
-      cs.push(data);
-      cs.push(null);
-    });
+    args.push(
+      // '-v', 'fatal',
+      // '-i', state.path,
+      // '-s', `${state.width}x${state.height}`,
+      // '-f', 'MJPEG',
+      // '-f', 'h264', '-vcodec',
+      // '-q:v', scale(state.quality, 0, 1, 30, 1),
+      '-f', 'MJPEG',
+      '-vframes', 1
+    );
+
+    if (state.pipe) {
+      args.push('pipe:1');
+    } else {
+      args.push('/tmp/capture.jpg');
+    }
+  }
+
+  var ffmpeg = cp.spawn('ffmpeg', args);
+
+  if (state.stream) {
+    state.isStreaming = true;
   }
+
+  ffmpeg.stdout.on('data', (data) => {
+    if (state.isStreaming) {
+      cs.push(data);
+      this.emit('data', data);
+    } else {
+      buffer = data;
+    }
+  });
+
+  ffmpeg.on('close', (code) => {
+    var error = code === 0 ? null : error;
+
+    state.isStreaming = false;
+
+    if (error) {
+      this.emit('error', error);
+    } else {
+      if (state.pipe) {
+        this.emit('data', buffer);
+        cs.push(buffer);
+        cs.push(null);
+      } else {
+        // This path is only taken for still captures that
+        // would like to store the image on the disc.
+        //
+        // TODO: allow program specified target locations
+        //
+        fs.readFile('/tmp/capture.jpg', (error, data) => {
+          this.emit('data', data);
+          cs.push(data);
+          cs.push(null);
+        });
+      }
+    }
+  });
+
   return cs;
 };
 
+Camera.prototype.stream = function() {
+  // TODO: Accept options/array of custom ffmpeg settings
+  return this.capture({
+    stream: true,
+    pipe: true
+  });
+};
+
 var cameraDefaults = {
   width: 320,
   height: 240,
-  quality: 100,
+  // 0-1 fractional percent. 1 => best, 0 => worst.
+  // maps to: ffmpeg -q:v 1-30 (Lower number is better)
+  quality: 1,
   path: '/dev/video0',
 };
 
@@ -106,13 +195,4 @@ module.exports = function(options) {
 
 if (global.IS_TEST_ENV) {
   module.exports.CaptureStream = CaptureStream;
-  module.exports.FSWebcam = FSWebcam;
-  module.exports.binding = global.IS_TEST_ENV ? stub : require('bindings')('capture.node');
-  module.exports.isDarwin = function(value) {
-    if (typeof value === 'undefined') {
-      return isDarwin;
-    } else {
-      isDarwin = value;
-    }
-  };
 }
diff --git a/lib/index.js b/lib/index.js
@@ -6,10 +6,7 @@ var install = require('./install');
 
 
 module.exports = {
-  Camera: function(args) {
-    install('fswebcam');
-    return new Camera(args);
-  },
+  Camera: Camera,
   Player: function(args) {
     install('madplay');
     return new Player(args);
@@ -19,7 +16,6 @@ module.exports = {
     install('madplay');
     return new Speaker(args);
   },
-
   // TODO...
   Microphone: null,
 };
diff --git a/test/.jshintrc b/test/.jshintrc
@@ -25,8 +25,10 @@
     "stream": true,
     "Emitter": true,
     "Readable": true,
+    "Writable": true,
     "bindings": true,
     "sinon": true,
+    "MemoryStream": true,
     "av": true,
     "Camera": true,
     "Player": true,

diff --git a/test/common/bootstrap.js b/test/common/bootstrap.js
@@ -10,6 +10,7 @@ global.util = require('util');
 
 global.Emitter = events.EventEmitter;
 global.Readable = stream.Readable;
+global.Writable = stream.Writable;
 
 
 // Third Party