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| 1 <!DOCTYPE html> | |
| 2 | |
| 3 <!-- | |
| 4 Tests that GainNode is properly scaling the gain. | |
| 5 We'll render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1. | |
| 6 The 11th note will be of gain 0.0, so it should be silent (at the end in the ren
dered output). | |
| 7 --> | |
| 8 | |
| 9 <html> | |
| 10 <head> | |
| 11 <script src="resources/audit-util.js"></script> | |
| 12 <script src="resources/audio-testing.js"></script> | |
| 13 | |
| 14 </head> | |
| 15 <body> | |
| 16 | |
| 17 <script> | |
| 18 | |
| 19 window.onload = init; | |
| 20 | |
| 21 var sampleRate = 44100.0; | |
| 22 var bufferDurationSeconds = 0.125; | |
| 23 var numberOfNotes = 11; | |
| 24 var noteSpacing = bufferDurationSeconds + 0.020; // leave 20ms of silence betwee
n each "note" | |
| 25 var lengthInSeconds = numberOfNotes * noteSpacing; | |
| 26 | |
| 27 var context = 0; | |
| 28 var sinWaveBuffer = 0; | |
| 29 | |
| 30 function createSinWaveBuffer(lengthInSeconds, frequency) { | |
| 31 var audioBuffer = context.createBuffer(2, lengthInSeconds * sampleRate, samp
leRate); | |
| 32 | |
| 33 var n = audioBuffer.length; | |
| 34 var channelL = audioBuffer.getChannelData(0); | |
| 35 var channelR = audioBuffer.getChannelData(1); | |
| 36 | |
| 37 for (var i = 0; i < n; ++i) { | |
| 38 channelL[i] = Math.sin(frequency * 2.0*Math.PI * i / sampleRate); | |
| 39 channelR[i] = channelL[i]; | |
| 40 } | |
| 41 | |
| 42 return audioBuffer; | |
| 43 } | |
| 44 | |
| 45 function playNote(time, gain) { | |
| 46 var source = context.createBufferSource(); | |
| 47 source.buffer = sinWaveBuffer; | |
| 48 | |
| 49 var gainNode = context.createGain(); | |
| 50 gainNode.gain.value = gain; | |
| 51 | |
| 52 source.connect(gainNode); | |
| 53 gainNode.connect(context.destination); | |
| 54 | |
| 55 source.start(time); | |
| 56 } | |
| 57 | |
| 58 function init() { | |
| 59 if (!window.testRunner) | |
| 60 return; | |
| 61 | |
| 62 // Create offline audio context. | |
| 63 context = new OfflineAudioContext(2, sampleRate * lengthInSeconds, sampleRat
e); | |
| 64 | |
| 65 // Create a buffer for a short "note". | |
| 66 sinWaveBuffer = createSinWaveBuffer(bufferDurationSeconds, 880.0); | |
| 67 | |
| 68 // Render 11 notes, starting at a gain of 1.0, decreasing in gain by 0.1. | |
| 69 // The last note will be of gain 0.0, so shouldn't be perceptible in the ren
dered output. | |
| 70 for (var i = 0; i < numberOfNotes; ++i) { | |
| 71 var time = i * noteSpacing; | |
| 72 var gain = 1.0 - i / (numberOfNotes - 1); | |
| 73 playNote(time, gain); | |
| 74 } | |
| 75 | |
| 76 context.oncomplete = finishAudioTest; | |
| 77 context.startRendering(); | |
| 78 | |
| 79 testRunner.waitUntilDone(); | |
| 80 } | |
| 81 | |
| 82 </script> | |
| 83 | |
| 84 </body> | |
| 85 </html> | |
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Chromium Code Reviews
Issue 2581463002:
Refactor WebAudio test directory (Closed)
