Adding ability to disable quality option. Some systems does not suppo…

…rt this option and can display cropped image. In order to disable quality you should set quality option to false (ex : new rtsp.FFMpeg({input: uri, resolution: '1280x720', quality:false, rate:10});)

lib/rtsp-ffmpeg.js

@@ -25,7 +25,7 @@ var FFMpeg = function(options) {
 	}
 	this.rate = options.rate || 10;
 	this.resolution = options.resolution;
-	this.quality = options.quality || '3';
+	this.quality = (options.quality === undefined || options.quality === "") ? 3 : options.quality;
 	this.arguments = options.arguments || [];
 
 	this.on('newListener', newListener.bind(this));
@@ -67,14 +67,16 @@ FFMpeg.prototype._args = function() {
 	return this.arguments.concat([
 		'-loglevel', 'quiet'
 		, '-i', this.input
-		, '-r', this.rate.toString()
+		, '-r', this.rate.toString()]
+		, this.quality ? ['-q:v', this.quality.toString()] : [],
+	[
 		//, '-vf', 'fps=25'
-		, '-q:v', this.quality.toString()
 		//, '-b:v', '32k'
-		, '-f', 'image2'
+		'-f', 'image2'
 		, '-updatefirst', '1'
 		, '-'
-	], this.resolution ? ['-s', this.resolution] : []);
+	]
+	, this.resolution ? ['-s', this.resolution] : []);
 };
 
 /**