| <!DOCTYPE html> |
| <!-- |
| Tests that an audio-rate signal (AudioNode output) can be connected to an |
| AudioParam. Specifically, this tests that an audio-rate signal coming from an |
| AudioBufferSourceNode playing an AudioBuffer containing a specific curve can be |
| connected to an AudioGainNode's .gain attribute (an AudioParam). Another |
| AudioBufferSourceNode will be the audio source having its gain changed. We load |
| this one with an AudioBuffer containing a constant value of 1. Thus it's easy |
| to check that the resultant signal should be equal to the gain-scaling curve. |
| --> |
| <html> |
| <head> |
| <title> |
| audioparam-connect-audioratesignal.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"> |
| let audit = Audit.createTaskRunner(); |
| |
| let sampleRate = 44100.0; |
| let lengthInSeconds = 1; |
| |
| let context = 0; |
| let constantOneBuffer = 0; |
| let linearRampBuffer = 0; |
| |
| function checkResult(renderedBuffer, should) { |
| let renderedData = renderedBuffer.getChannelData(0); |
| let expectedData = linearRampBuffer.getChannelData(0); |
| let n = renderedBuffer.length; |
| |
| should(n, 'Rendered signal length').beEqualTo(linearRampBuffer.length); |
| |
| // Check that the rendered result exactly matches the buffer used to |
| // control gain. This is because we're changing the gain of a signal |
| // having constant value 1. |
| let success = true; |
| for (let i = 0; i < n; ++i) { |
| if (renderedData[i] != expectedData[i]) { |
| success = false; |
| break; |
| } |
| } |
| |
| should( |
| success, |
| 'Rendered signal exactly matches the audio-rate gain changing signal') |
| .beTrue(); |
| } |
| |
| audit.define('test', function(task, should) { |
| let sampleFrameLength = sampleRate * lengthInSeconds; |
| |
| // Create offline audio context. |
| context = new OfflineAudioContext(1, sampleFrameLength, sampleRate); |
| |
| // Create buffer used by the source which will have its gain controlled. |
| constantOneBuffer = createConstantBuffer(context, sampleFrameLength, 1); |
| |
| // Create buffer used to control gain. |
| linearRampBuffer = createLinearRampBuffer(context, sampleFrameLength); |
| |
| // Create the two sources. |
| |
| let constantSource = context.createBufferSource(); |
| constantSource.buffer = constantOneBuffer; |
| |
| let gainChangingSource = context.createBufferSource(); |
| gainChangingSource.buffer = linearRampBuffer; |
| |
| // Create a gain node controlling the gain of constantSource and make |
| // the connections. |
| let gainNode = context.createGain(); |
| |
| // Intrinsic baseline gain of zero. |
| gainNode.gain.value = 0; |
| |
| constantSource.connect(gainNode); |
| gainNode.connect(context.destination); |
| |
| // Connect an audio-rate signal to control the .gain AudioParam. |
| // This is the heart of what is being tested. |
| gainChangingSource.connect(gainNode.gain); |
| |
| // Start both sources at time 0. |
| constantSource.start(0); |
| gainChangingSource.start(0); |
| |
| context.startRendering().then(buffer => { |
| checkResult(buffer, should); |
| task.done(); |
| }); |
| }); |
| |
| audit.run(); |
| </script> |
| </body> |
| </html> |
