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| 1 <!DOCTYPE html> | |
| 2 <html> | |
| 3 | |
| 4 <head> | |
| 5 <script src="../resources/js-test.js"></script> | |
| 6 <script src="resources/compatibility.js"></script> | |
| 7 <script src="resources/audit-util.js"></script> | |
| 8 <script src="resources/audio-testing.js"></script> | |
| 9 </head> | |
| 10 | |
| 11 <body> | |
| 12 <script> | |
| 13 description('AudioBufferSourceNode: DC-driven playbackRate modulation.'); | |
| 14 window.jsTestIsAsync = true; | |
| 15 | |
| 16 var sampleRate = 44100; | |
| 17 | |
| 18 // To get an observable change on playbackRate modulation, the minimum | |
| 19 // rendering length should greater than the rendering quantum. | |
| 20 var renderLength = 256; | |
| 21 var half = renderLength / 2; | |
| 22 | |
| 23 // With the playbackRate of 1, the duration of impulse buffer should be 4 | |
| 24 // samples (which means the interval between impulses is 4). Doubling | |
| 25 // playback speed decrease the interval to 2 samples. | |
| 26 var impulseLength = 4; | |
| 27 | |
| 28 var context = new OfflineAudioContext(1, renderLength, sampleRate); | |
| 29 var impulseBuffer, dcOffsetBuffer; | |
| 30 | |
| 31 var audit = Audit.createTaskRunner(); | |
| 32 | |
| 33 | |
| 34 // Task: build an impulse and DC-offset buffers for testing. | |
| 35 audit.defineTask('build-buffers', function (done) { | |
| 36 // 4-sample impulse sample. | |
| 37 impulseBuffer = createImpulseBuffer(context, impulseLength); | |
| 38 | |
| 39 // Create a DC offset buffer with 2 values [0, 1] for modulating | |
| 40 // playbackRate. The first half of buffer is 0 and the rest is 1. | |
| 41 dcOffsetBuffer = context.createBuffer(1, renderLength, sampleRate); | |
| 42 var dcOffsetArray = dcOffsetBuffer.getChannelData(0); | |
| 43 for (i = 0; i < dcOffsetArray.length; i++) { | |
| 44 | |
| 45 // Note that these values will be added to the playbackRate AudioParam | |
| 46 // value. For example, 0 DC offset value will result playbackRate of 1 | |
| 47 // because the default playbackRate value is 1. | |
| 48 dcOffsetArray[i] = i < half ? 0 : 1; | |
| 49 } | |
| 50 | |
| 51 done(); | |
| 52 }); | |
| 53 | |
| 54 | |
| 55 // Task: Render the actual buffer and compare with the reference. | |
| 56 audit.defineTask('synthesize-verify', function (done) { | |
| 57 var impulse = context.createBufferSource(); | |
| 58 var dcOffset = context.createBufferSource(); | |
| 59 | |
| 60 impulse.buffer = impulseBuffer; | |
| 61 dcOffset.buffer = dcOffsetBuffer; | |
| 62 impulse.loop = true; | |
| 63 | |
| 64 impulse.connect(context.destination); | |
| 65 dcOffset.connect(impulse.playbackRate); | |
| 66 | |
| 67 impulse.start(); | |
| 68 dcOffset.start(); | |
| 69 | |
| 70 context.startRendering().then(function (renderedBuffer) { | |
| 71 var data = renderedBuffer.getChannelData(0); | |
| 72 var passed = true, i = 0; | |
| 73 var nextImpulseIndex = 0; | |
| 74 | |
| 75 while (i < renderLength) { | |
| 76 if (i === nextImpulseIndex && data[i] === 1) { | |
| 77 // From 0 to 127th element, the interval between impulses is 4. On t
he other | |
| 78 // hand, the interval is 2 between 128th and 255th element. | |
| 79 nextImpulseIndex += (i < half) ? impulseLength : impulseLength / 2; | |
| 80 } else if (data[i] !== 0) { | |
| 81 // If a value is neither 0 or 1, break the loop and fail the test. | |
| 82 passed = false; | |
| 83 break; | |
| 84 } | |
| 85 | |
| 86 i++; | |
| 87 } | |
| 88 | |
| 89 if (passed) { | |
| 90 testPassed('Doubling playbackRate decreased the interval between impul
ses to half.'); | |
| 91 } else { | |
| 92 testFailed('Doubling playbackRate produced the incorrect result' + | |
| 93 'at the index ' + i + '.'); | |
| 94 } | |
| 95 }).then(done); | |
| 96 }); | |
| 97 | |
| 98 audit.defineTask('finish', function (done) { | |
| 99 finishJSTest(); | |
| 100 done(); | |
| 101 }); | |
| 102 | |
| 103 audit.runTasks( | |
| 104 'build-buffers', | |
| 105 'synthesize-verify', | |
| 106 'finish' | |
| 107 ); | |
| 108 | |
| 109 successfullyParsed = true; | |
| 110 </script> | |
| 111 </body> | |
| 112 | |
| 113 </html> | |
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Chromium Code Reviews
Issue 2581463002:
Refactor WebAudio test directory (Closed)
