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Diffstat (limited to 'testing/web-platform/tests/webaudio/the-audio-api/the-gainnode-interface/gain.html')
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diff --git a/testing/web-platform/tests/webaudio/the-audio-api/the-gainnode-interface/gain.html b/testing/web-platform/tests/webaudio/the-audio-api/the-gainnode-interface/gain.html new file mode 100644 index 0000000000..c41f4c9080 --- /dev/null +++ b/testing/web-platform/tests/webaudio/the-audio-api/the-gainnode-interface/gain.html @@ -0,0 +1,162 @@ +<!DOCTYPE html> +<html> + <head> + <title> + Basic GainNode Functionality + </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"> + // Tests that GainNode is properly scaling the gain. We'll render 11 + // notes, starting at a gain of 1.0, decreasing in gain by 0.1. The 11th + // note will be of gain 0.0, so it should be silent (at the end in the + // rendered output). + + let audit = Audit.createTaskRunner(); + + // Use a power of two to eliminate any round-off when converting frame to + // time. + let sampleRate = 32768; + // Make sure the buffer duration and spacing are all exact frame lengths + // so that the note spacing is also on frame boundaries to eliminate + // sub-sample accurate start of a ABSN. + let bufferDurationSeconds = Math.floor(0.125 * sampleRate) / sampleRate; + let numberOfNotes = 11; + // Leave about 20ms of silence, being sure this is an exact frame + // duration. + let noteSilence = Math.floor(0.020 * sampleRate) / sampleRate; + let noteSpacing = bufferDurationSeconds + noteSilence; + + let lengthInSeconds = numberOfNotes * noteSpacing; + + let context = 0; + let sinWaveBuffer = 0; + + // Create a stereo AudioBuffer of duration |lengthInSeconds| consisting of + // a pure sine wave with the given |frequency|. Both channels contain the + // same data. + function createSinWaveBuffer(lengthInSeconds, frequency) { + let audioBuffer = + context.createBuffer(2, lengthInSeconds * sampleRate, sampleRate); + + let n = audioBuffer.length; + let channelL = audioBuffer.getChannelData(0); + let channelR = audioBuffer.getChannelData(1); + + for (let i = 0; i < n; ++i) { + channelL[i] = Math.sin(frequency * 2.0 * Math.PI * i / sampleRate); + channelR[i] = channelL[i]; + } + + return audioBuffer; + } + + function playNote(time, gain, merger) { + let source = context.createBufferSource(); + source.buffer = sinWaveBuffer; + + let gainNode = context.createGain(); + gainNode.gain.value = gain; + + let sourceSplitter = context.createChannelSplitter(2); + let gainSplitter = context.createChannelSplitter(2); + + // Split the stereo channels from the source output and the gain output + // and merge them into the desired channels of the merger. + source.connect(gainNode).connect(gainSplitter); + source.connect(sourceSplitter); + + gainSplitter.connect(merger, 0, 0); + gainSplitter.connect(merger, 1, 1); + sourceSplitter.connect(merger, 0, 2); + sourceSplitter.connect(merger, 1, 3); + + source.start(time); + } + + audit.define( + {label: 'create context', description: 'Create context for test'}, + function(task, should) { + // Create offline audio context. + context = new OfflineAudioContext( + 4, sampleRate * lengthInSeconds, sampleRate); + task.done(); + }); + + audit.define( + {label: 'test', description: 'GainNode functionality'}, + function(task, should) { + let merger = new ChannelMergerNode( + context, {numberOfInputs: context.destination.channelCount}); + merger.connect(context.destination); + + // Create a buffer for a short "note". + sinWaveBuffer = createSinWaveBuffer(bufferDurationSeconds, 880.0); + + let startTimes = []; + let gainValues = []; + + // Render 11 notes, starting at a gain of 1.0, decreasing in gain by + // 0.1. The last note will be of gain 0.0, so shouldn't be + // perceptible in the rendered output. + for (let i = 0; i < numberOfNotes; ++i) { + let time = i * noteSpacing; + let gain = 1.0 - i / (numberOfNotes - 1); + startTimes.push(time); + gainValues.push(gain); + playNote(time, gain, merger); + } + + context.startRendering() + .then(buffer => { + let actual0 = buffer.getChannelData(0); + let actual1 = buffer.getChannelData(1); + let reference0 = buffer.getChannelData(2); + let reference1 = buffer.getChannelData(3); + + // It's ok to a frame too long since the sine pulses are + // followed by silence. + let bufferDurationFrames = + Math.ceil(bufferDurationSeconds * context.sampleRate); + + // Apply the gains to the reference signal. + for (let k = 0; k < startTimes.length; ++k) { + // It's ok to be a frame early because the sine pulses are + // preceded by silence. + let startFrame = + Math.floor(startTimes[k] * context.sampleRate); + let gain = gainValues[k]; + for (let n = 0; n < bufferDurationFrames; ++n) { + reference0[startFrame + n] *= gain; + reference1[startFrame + n] *= gain; + } + } + + // Verify the channels are clsoe to the reference. + should(actual0, 'Left output from gain node') + .beCloseToArray( + reference0, {relativeThreshold: 1.1877e-7}); + should(actual1, 'Right output from gain node') + .beCloseToArray( + reference1, {relativeThreshold: 1.1877e-7}); + + // Test the SNR too for both channels. + let snr0 = 10 * Math.log10(computeSNR(actual0, reference0)); + let snr1 = 10 * Math.log10(computeSNR(actual1, reference1)); + should(snr0, 'Left SNR (in dB)') + .beGreaterThanOrEqualTo(148.71); + should(snr1, 'Right SNR (in dB)') + .beGreaterThanOrEqualTo(148.71); + }) + .then(() => task.done()); + ; + }); + + audit.run(); + </script> + </body> +</html> |