README and forkme.

rowild · Oct 5, 2012 · be871b3 · be871b3
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Showing 4 changed files with 47 additions and 3 deletions.
diff --git a/README.md b/README.md
@@ -0,0 +1,7 @@
+# Naive simple pitch detection
+
+I whipped this app up to start experimenting with pitch detection, and also to test live audio input.  It performs a naive (zero-crossing based) pitch detection algorithm in realtime.  It works best today with whistling (which has a clear, simple waveform); it needs some severe help with more complex waveforms, even like guitar.  I'll get back to this eventually.  :)  There are much better tuners out there right now - like [Craig Spence's work](http://phenomnomnominal.github.com/).
+
+Check it out, feel free to fork, submit pull requests, etc.
+
+-Chris
diff --git a/img/forkme.png b/img/forkme.png
diff --git a/index.html b/index.html
@@ -23,7 +23,8 @@
 <body>
 <script src="js/pitchdetect.js"></script>
 
-<button onclick="this.innerText = togglePlayback()">start</button>
+<button onclick="this.innerText = togglePlayback()">use demo audio</button>
+<button onclick="toggleLiveInput()">use live input</button>
 <!--<button onclick="updatePitch(0);">sample</button>-->
 
 <div id="detector" class="vague">
@@ -32,6 +33,7 @@
 <div class="note"><span id="note">--</span></div>   
 <div id="detune"><span id="detune_amt">--</span><span id="flat">cents &#9837;</span><span id="sharp">cents &#9839;</span></div>
 </div>
+<a href="https://github.com/cwilso/pitchdetect" style="position: absolute; z-index:2; top: 0; right: 0; border: 0;"><img src="img/forkme.png" alt="Fork me on GitHub"></a>
 
 </body>
 </html>
diff --git a/js/pitchdetect.js b/js/pitchdetect.js
@@ -12,7 +12,7 @@ var detectorElem,
 
 window.onload = function() {
 	var request = new XMLHttpRequest();
-	request.open("GET", "../sounds/whistling2.ogg", true);
+	request.open("GET", "../sounds/whistling3.ogg", true);
 	request.responseType = "arraybuffer";
 	request.onload = function() {
 	  audioContext.decodeAudioData( request.response, function(buffer) { 
@@ -49,8 +49,37 @@ window.onload = function() {
 		};
 	  	reader.readAsArrayBuffer(e.dataTransfer.files[0]);
 	  	return false;
-	};	
+	};
+
+
 
+}
+
+        function error() {
+            alert('Stream generation failed.');
+        }
+
+        function getUserMedia(dictionary, callback) {
+            try {
+                navigator.webkitGetUserMedia(dictionary, callback, error);
+            } catch (e) {
+                alert('webkitGetUserMedia threw exception :' + e);
+            }
+        }
+
+        function gotStream(stream) {
+            // Create an AudioNode from the stream.
+            var mediaStreamSource = audioContext.createMediaStreamSource(stream);
+
+            // Connect it to the destination.
+    analyser = audioContext.createAnalyser();
+    analyser.fftSize = 2048;
+    mediaStreamSource.connect( analyser );
+    updatePitch();
+}
+
+function toggleLiveInput() {
+    getUserMedia({audio:true}, gotStream);
 }
 
 function togglePlayback() {
@@ -76,6 +105,7 @@ function togglePlayback() {
     analyser.connect( audioContext.destination );
     sourceNode.noteOn( now );
     isPlaying = true;
+    isLiveInput = false;
     updatePitch();
 
     return "stop";
@@ -146,12 +176,17 @@ function updatePitch( time ) {
 	// find the first point
 	var last_zero = findNextPositiveZeroCrossing( 0 );
 
+	var n=0;
 	// keep finding points, adding cycle lengths to array
 	while ( last_zero != -1) {
 		var next_zero = findNextPositiveZeroCrossing( last_zero + 1 );
 		if (next_zero > -1)
 			cycles.push( next_zero - last_zero );
 		last_zero = next_zero;
+
+		n++;
+		if (n>1000)
+			break;
 	}
 
 	// 1?: average the array