| <!DOCTYPE html> |
| <html> |
| <head> |
| <title> |
| audiochannelmerger-cycle.html |
| </title> |
| <script src="../../imported/w3c/web-platform-tests/resources/testharness.js"></script> |
| <script src="../../resources/testharnessreport.js"></script> |
| <script src="../resources/audit-util.js"></script> |
| <script src="../resources/audit.js"></script> |
| </head> |
| <body> |
| <script id="layout-test-code"> |
| // This specific sample rate is chosen to avoid the round/truncation error |
| // in delay time. See: crbug.com/448801 |
| let sampleRate = 32768; |
| |
| // Web Audio API's rendering quantum. |
| let renderingQuantum = 128; |
| |
| // 4x of rendering quantum. This is to make the rendered result long |
| // enough so that we can observe the delayed output. |
| let renderLength = renderingQuantum * 4; |
| |
| // 1x rendering quantum of delay. |
| let delayTime = renderingQuantum / sampleRate; |
| |
| // Use 2 channels as a test case. |
| let numberOfChannels = 2; |
| |
| let audit = Audit.createTaskRunner(); |
| |
| audit.define('merger-cyclic-graph', (task, should) => { |
| |
| let context = |
| new OfflineAudioContext(numberOfChannels, renderLength, sampleRate); |
| let merger = context.createChannelMerger(2); |
| let delay = context.createDelay(); |
| let source = context.createBufferSource(); |
| |
| // Create a mono source buffer filled with '1'. |
| source.buffer = createConstantBuffer(context, renderLength, [1]); |
| |
| delay.delayTime.value = delayTime; |
| |
| // Connect the source to input 0 of the merger. Connect the output of |
| // the merger to a delay node whose output is then connected to input 1 |
| // of the merger. See: crbug.com/442925 |
| source.connect(merger, 0, 0); |
| delay.connect(merger, 0, 1); |
| merger.connect(delay); |
| merger.connect(context.destination); |
| source.start(); |
| |
| context.startRendering().then(function(buffer) { |
| // Expected output values: the output of delay node will be a stereo |
| // signal of [1, 0]. When it feeds back to the 2nd input of merger |
| // node, the stereo channel will be summed to mono resulting in 0.5. |
| let expected_left = []; |
| let expected_right = []; |
| |
| for (let i = 0; i < renderLength; i++) { |
| // Note that the delayed channel will be zero for the first 128 |
| // samples due to the cyclic audio graph, the second 128 sample will |
| // be also zero because of 128 samples delay. |
| expected_left[i] = 1.0; |
| expected_right[i] = (i < renderingQuantum * 2) ? 0.0 : 0.5; |
| } |
| |
| let actual_left = buffer.getChannelData(0); |
| let actual_right = buffer.getChannelData(1); |
| should(actual_left, 'Left channel').beEqualToArray(expected_left); |
| should(actual_right, 'Right channel').beEqualToArray(expected_right); |
| |
| task.done(); |
| }); |
| |
| }); |
| |
| audit.run(); |
| </script> |
| </body> |
| </html> |
