web audio api + angularjs
DESCRIPTION
Using Angular to help organize the visualization of multiple audio tracks. Demo: http://cbateman.com/demos/AudioTrackr/TRANSCRIPT
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var request = new XMLHttpRequest(); request.open('GET', myURL, true); request.responseType = 'arraybuffer‘; request.onload = requestLoad; request.send(); function requestLoad() { // yay, finally done loading _audioContext.decodeAudioData(request.response, doneDecoding); } function doneDecoding(buffer) { // yay, finally done decoding playBuffer(buffer); } function playBuffer(buffer) { var bufferSourceNode = _audioContext.createBufferSource(); bufferSourceNode.buffer = buffer; buffer.connect(_audioContext.destination); // connect to output buffer.start(0); //play }
// create an HTML Audio Element, or use an existing one var audio = new Audio(myURL); // Audio Element will let us know when it's buffered enough audio.addEventListener('canplaythrough', function(e) { var mediaSourceNode = _audioContext.createMediaElementSource(audio); mediaSourceNode.connect(_audioContext.destination); // connect to output audio.play(); // play });
<body ng-app="Page" ng-controller="PageController"> <div class="songs"> <span ng-repeat="song in songs"> <input type="radio" ng-model="$parent.currentSong" ng-value="song" /> <label>{{song.name+' ('+song.band+')'}}</label> </span> </div> <div class="controls" ng-show="currentSong“> <h2>{{currentSong.name}}</h2> <button ng-show="!playing" ng-click="playTracks()">Play</button> <button ng-show="playing" ng-click="stopTracks()">Stop</button> </div> <div class="track-container"> <div ng-controller="TrackController" class="track" ng-class="{loading:loading==true}" ng-repeat="(key, track) in currentSong.tracks"> <input type="range" ng-model="trackVolume" /> <canvas></canvas> <span class="spinner" ng-show="loading"></span> </div> </div> </body>
<body ng-app="Page" ng-controller="PageController"> <div class="songs"> <span ng-repeat="song in songs"> <input type="radio" ng-model="$parent.currentSong" ng-value="song" /> <label>{{song.name+' ('+song.band+')'}}</label> </span> </div> <div class="controls" ng-show="currentSong“> <h2>{{currentSong.name}}</h2> <button ng-show="!playing" ng-click="playTracks()">Play</button> <button ng-show="playing" ng-click="stopTracks()">Stop</button> </div> <div class="track-container"> <div ng-controller="TrackController" class="track" ng-class="{loading:loading==true}" ng-repeat="(key, track) in currentSong.tracks"> <input type="range" ng-model="trackVolume" /> <canvas></canvas> <span class="spinner" ng-show="loading"></span> </div> </div> </body>
_page.controller('PageController', function($scope) { ... $scope.playTracks = function(tracks) { angular.forEach(tracks, function(track, key) { track.play(); }); $scope.playing = true; }; function tick() { angular.forEach($scope.currentSong.tracks, function(track, key) { if (track.analyser) { _drawStuff(track.cCtx, track.analyser); } }); window.requestAnimationFrame(tick); } ... });
_page.controller('TrackController', function($scope, $element) { $scope.trackVolume = 100; $scope.canvas = $element[0].getElementsByTagName('canvas')[0]; $scope.track.play = function() { $scope.track.audio.play(); }; $scope.track.stop = function() { $scope.track.audio.pause(); }; $scope.$watch('trackVolume', function(value) { value = value / 100; if ($scope.track.gainNode) { $scope.track.gainNode.gain.value = value; } }); });
var analyser = _aCtx.createAnalyser(); analyser.smoothingTimeConstant = 0.6; analyser.fftSize = 256;
// Each frame: var byteFreqArr = new Uint8Array(analyser.frequencyBinCount); analyser.getByteFrequencyData(byteFreqArr); var timeDomainArr = new Uint8Array(analyser.frequencyBinCount); analyser.getByteTimeDomainData(timeDomainArr); canvasContext.clearRect(0, 0, _cWidth, _cHeight); canvasContext.beginPath(); for (var i=0,iLen=byteFreqArr.length; i<iLen; i++) { canvasContext.fillRect(i*_freqDrawWidth, _cHeight - (byteFreqArr[i] / 256 * _cHeight), (_freqDrawWidth - 2), _cHeight); var percent = timeDomainArr[i] / 256; var offset = _cHeight - (percent * _cHeight) - 1; canvasContext.lineTo(i*_timeDrawWidth, offset); } canvasContext.stroke();
