| <!DOCTYPE html> |
| <html> |
| <head> |
| <title> |
| audiobuffersource-playbackrate-zero.html |
| </title> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script src="/webaudio/resources/audit-util.js"></script> |
| <script src="/webaudio/resources/audit.js"></script> |
| </head> |
| <body> |
| <script id="layout-test-code"> |
| // Sample rate should be power of 128 to observe the change of AudioParam |
| // at the beginning of rendering quantum. (playbackRate is k-rate) This is |
| // the minimum sample rate in the valid sample rate range. |
| let sampleRate = 8192; |
| |
| // The render duration in seconds, and the length in samples. |
| let renderDuration = 1.0; |
| let renderLength = renderDuration * sampleRate; |
| |
| let context = new OfflineAudioContext(1, renderLength, sampleRate); |
| let audit = Audit.createTaskRunner(); |
| |
| |
| // Task: Render the actual buffer and compare with the reference. |
| audit.define('synthesize-verify', (task, should) => { |
| let ramp = context.createBufferSource(); |
| let rampBuffer = createLinearRampBuffer(context, renderLength); |
| ramp.buffer = rampBuffer; |
| |
| ramp.connect(context.destination); |
| ramp.start(); |
| |
| // Leave the playbackRate as 1 for the first half, then change it |
| // to zero at the exact half. The zero playback rate should hold the |
| // sample value of the buffer index at the moment. (sample-and-hold) |
| ramp.playbackRate.setValueAtTime(1.0, 0.0); |
| ramp.playbackRate.setValueAtTime(0.0, renderDuration / 2); |
| |
| context.startRendering() |
| .then(function(renderedBuffer) { |
| let data = renderedBuffer.getChannelData(0); |
| let rampData = rampBuffer.getChannelData(0); |
| let half = rampData.length / 2; |
| let passed = true; |
| let i; |
| |
| for (i = 1; i < rampData.length; i++) { |
| if (i < half) { |
| // Before the half position, the actual should match with the |
| // original ramp data. |
| if (data[i] !== rampData[i]) { |
| passed = false; |
| break; |
| } |
| } else { |
| // From the half position, the actual value should not change. |
| if (data[i] !== rampData[half]) { |
| passed = false; |
| break; |
| } |
| } |
| } |
| |
| should(passed, 'The zero playbackRate') |
| .message( |
| 'held the sample value correctly', |
| 'should hold the sample value. ' + |
| 'Expected ' + rampData[half] + ' but got ' + data[i] + |
| ' at the index ' + i); |
| }) |
| .then(() => task.done()); |
| }); |
| |
| audit.define('subsample start with playback rate 0', (task, should) => { |
| let context = new OfflineAudioContext(1, renderLength, sampleRate); |
| let rampBuffer = new AudioBuffer( |
| {length: renderLength, sampleRate: context.sampleRate}); |
| let data = new Float32Array(renderLength); |
| let startValue = 5; |
| for (let k = 0; k < data.length; ++k) { |
| data[k] = k + startValue; |
| } |
| rampBuffer.copyToChannel(data, 0); |
| |
| let src = new AudioBufferSourceNode( |
| context, {buffer: rampBuffer, playbackRate: 0}); |
| |
| src.connect(context.destination); |
| |
| // Purposely start the source between frame boundaries |
| let startFrame = 27.3; |
| src.start(startFrame / context.sampleRate); |
| |
| context.startRendering() |
| .then(audioBuffer => { |
| let actualStartFrame = Math.ceil(startFrame); |
| let audio = audioBuffer.getChannelData(0); |
| |
| should( |
| audio.slice(0, actualStartFrame), |
| `output[0:${actualStartFrame - 1}]`) |
| .beConstantValueOf(0); |
| should( |
| audio.slice(actualStartFrame), `output[${actualStartFrame}:]`) |
| .beConstantValueOf(startValue); |
| }) |
| .then(() => task.done()); |
| }); |
| |
| audit.run(); |
| </script> |
| </body> |
| </html> |
