| <!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> |
| <script src="resources/audio-testing.js"></script> |
| <script src="../resources/js-test.js"></script> |
| |
| </head> |
| <body> |
| |
| <script> |
| |
| var sampleRate = 44100.0; |
| var lengthInSeconds = 1; |
| |
| var context = 0; |
| var constantOneBuffer = 0; |
| var linearRampBuffer = 0; |
| |
| function checkResult(event) { |
| var renderedBuffer = event.renderedBuffer; |
| var renderedData = renderedBuffer.getChannelData(0); |
| var expectedData = linearRampBuffer.getChannelData(0); |
| var n = renderedBuffer.length; |
| |
| if (n == linearRampBuffer.length) { |
| testPassed("Rendered signal is of correct length."); |
| } else { |
| testFailed("Rendered signal is not of correct 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. |
| var success = true; |
| for (var i = 0; i < n; ++i) { |
| if (renderedData[i] != expectedData[i]) { |
| success = false; |
| break; |
| } |
| } |
| |
| if (success) { |
| testPassed("Rendered signal exactly matches the audio-rate gain changing signal."); |
| } else { |
| testFailed("Rendered signal differs from the audio-rate gain changing signal."); |
| } |
| |
| finishJSTest(); |
| } |
| |
| function runTest() { |
| window.jsTestIsAsync = true; |
| |
| var sampleFrameLength = sampleRate * lengthInSeconds; |
| |
| // Create offline audio context. |
| context = new webkitOfflineAudioContext(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. |
| |
| var constantSource = context.createBufferSource(); |
| constantSource.buffer = constantOneBuffer; |
| |
| var gainChangingSource = context.createBufferSource(); |
| gainChangingSource.buffer = linearRampBuffer; |
| |
| // Create a gain node controlling the gain of constantSource and make the connections. |
| var 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.oncomplete = checkResult; |
| context.startRendering(); |
| } |
| |
| runTest(); |
| |
| </script> |
| </body> |
| </html> |
