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| 1 <!DOCTYPE html> | |
| 2 | |
| 3 <!-- | |
| 4 Tests that AudioBufferSourceNode supports loop-points with .loopStart and .loopE
nd. | |
| 5 --> | |
| 6 | |
| 7 <html> | |
| 8 <head> | |
| 9 <script src="resources/audit-util.js"></script> | |
| 10 <script src="resources/audio-testing.js"></script> | |
| 11 | |
| 12 </head> | |
| 13 <body> | |
| 14 | |
| 15 <script> | |
| 16 | |
| 17 window.onload = init; | |
| 18 | |
| 19 var sampleRate = 44100.0; | |
| 20 var numberOfNotes = 60; // play over a 5 octave range | |
| 21 var noteDuration = 0.025; | |
| 22 var noteSpacing = noteDuration + 0.005; // leave 5ms of silence between each "no
te" | |
| 23 var lengthInSeconds = numberOfNotes * noteSpacing; | |
| 24 | |
| 25 var context = 0; | |
| 26 var buffer = 0; | |
| 27 | |
| 28 function createTestBuffer(frequency, sampleRate) { | |
| 29 // Create a buffer containing two periods at this frequency. | |
| 30 // The 1st half is a pure sine wave period scaled by a linear ramp from 0 ->
1. | |
| 31 // The 2nd half of the buffer corresponds exactly to one pure sine wave peri
od. | |
| 32 var onePeriodDuration = 1 / frequency; | |
| 33 var sampleFrameLength = 2 * onePeriodDuration * sampleRate; | |
| 34 | |
| 35 var audioBuffer = context.createBuffer(1, sampleFrameLength, sampleRate); | |
| 36 | |
| 37 var n = audioBuffer.length; | |
| 38 var channelData = audioBuffer.getChannelData(0); | |
| 39 | |
| 40 for (var i = 0; i < n; ++i) { | |
| 41 var sample = Math.sin(frequency * 2.0*Math.PI * i / sampleRate); | |
| 42 | |
| 43 // Linear ramp from 0 -> 1 for the first period. | |
| 44 // Stay at 1 for the 2nd period. | |
| 45 var scale = i < n / 2 ? i / (n / 2) : 1; | |
| 46 sample *= scale; | |
| 47 | |
| 48 channelData[i] = sample; | |
| 49 } | |
| 50 | |
| 51 return audioBuffer; | |
| 52 } | |
| 53 | |
| 54 function playNote(time, duration, playbackRate) { | |
| 55 var source = context.createBufferSource(); | |
| 56 source.buffer = buffer; | |
| 57 source.playbackRate.value = playbackRate; | |
| 58 | |
| 59 var gainNode = context.createGain(); | |
| 60 source.connect(gainNode); | |
| 61 gainNode.connect(context.destination); | |
| 62 | |
| 63 // Loop the 2nd half of the buffer. | |
| 64 // We should be able to hear any problems as glitches if the looping incorre
ctly indexes to | |
| 65 // anywhere outside of the desired loop-points, since only the 2nd half is a
perfect sine-wave cycle, | |
| 66 // while the 1st half of the buffer contains a linear ramp of a sine-wave cy
cle. | |
| 67 source.loop = true; | |
| 68 source.loopStart = 0.5 * buffer.duration; | |
| 69 source.loopEnd = buffer.duration; | |
| 70 | |
| 71 // Play for the given duration. | |
| 72 source.start(time); | |
| 73 source.stop(time + duration); | |
| 74 | |
| 75 // Apply a quick linear fade-out to avoid a click at the end of the note. | |
| 76 gainNode.gain.value = 1; | |
| 77 gainNode.gain.setValueAtTime(1, time + duration - 0.005); | |
| 78 gainNode.gain.linearRampToValueAtTime(0, time + duration); | |
| 79 } | |
| 80 | |
| 81 function init() { | |
| 82 if (!window.testRunner) | |
| 83 return; | |
| 84 | |
| 85 // Create offline audio context. | |
| 86 context = new OfflineAudioContext(2, sampleRate * lengthInSeconds, sampleRat
e); | |
| 87 | |
| 88 // Create the test buffer. | |
| 89 // We'll loop this with the loop-points set for the 2nd half of this buffer. | |
| 90 buffer = createTestBuffer(440.0, sampleRate); | |
| 91 | |
| 92 // Play all the notes as a chromatic scale. | |
| 93 for (var i = 0; i < numberOfNotes; ++i) { | |
| 94 var time = i * noteSpacing; | |
| 95 var semitone = i - numberOfNotes/2; // start three octaves down | |
| 96 | |
| 97 // Convert from semitone to rate. | |
| 98 var playbackRate = Math.pow(2, semitone / 12); | |
| 99 | |
| 100 playNote(time, noteDuration, playbackRate); | |
| 101 } | |
| 102 | |
| 103 context.oncomplete = finishAudioTest; | |
| 104 context.startRendering(); | |
| 105 | |
| 106 testRunner.waitUntilDone(); | |
| 107 } | |
| 108 | |
| 109 </script> | |
| 110 | |
| 111 </body> | |
| 112 </html> | |
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Chromium Code Reviews
Issue 2581463002:
Refactor WebAudio test directory (Closed)
