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Commit 54eca3bd authored by Alice Boxhall's avatar Alice Boxhall Committed by Commit Bot
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Revert "Better interpolation of oscillator at low frequencies" 

This reverts commit 65d50038.

Reason for revert: Causing LayoutTest failures e.g. https://uberchromegw.corp.google.com/i/chromium.mac/builders/Mac10.10%20Tests/builds/25167

Original change's description:
> Better interpolation of oscillator at low frequencies
> 
> For low frequencies, use a 3-point or 5-point Lagrange interpolation
> scheme to improve the accuracy of the oscillator instead of using
> simple linear interpolation.
> 
> For a typical context, the linear interpolator is used if the
> frequency >= 3.2 Hz; the 3-point, for 3.2 > frequency > 1.7 Hz; and
> the 5-point for all other cases.  Thus, typical use-cases are not
> impaired by this change.
> 
> Some benchmark results from running an oscillator for 1000 seconds in an
> offline context.  This is the time measured from startRendering()
> until the promise is delivered.  The SNR is the measured SNR between
> the test signal and a reference 440 Hz signal.  The linear time was
> the same before and after this CL.
> 
> linear:
> time: 1844.6 ms, stddev: 154.4
> SNR: 27.7 dB
> 
> 3-point:
> time: 2426.5 ms, stddev: 265.0
> SNR: 37.2 dB
> 
> 5-point:
> time: 2752.6 ms, stddev: 215.1
> SNR: 59.3 dB
> 
> 7-point (for reference, not used now):
> time: 3239.4 ms, stddev: 263.8
> SNR: 82.5 dB
> 
> Bug: 773507
> Test: Oscillator/osc-440hz.html
> Change-Id: Ib49fab4fb27738f4f02bd41f8adcc2e3b2dd2137
> Reviewed-on: https://chromium-review.googlesource.com/713576
> Commit-Queue: Raymond Toy <rtoy@chromium.org>
> Reviewed-by: Hongchan Choi <hongchan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#510133}

TBR=rtoy@chromium.org,hongchan@chromium.org

Change-Id: If59bb7f8169b077c35e5d735c6f6f19cc780d512
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 773507
Reviewed-on: https://chromium-review.googlesource.com/729719Reviewed-by: default avatarAlice Boxhall <aboxhall@chromium.org>
Commit-Queue: Alice Boxhall <aboxhall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510257}
parent 69e46ae5
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Showing with 30 additions and 205 deletions
third_party/WebKit/LayoutTests/webaudio/Analyser/realtimeanalyser-freq-data.html
View file @ 54eca3bd
......@@ -38,7 +38,7 @@
minDecibels: -50,
floatRelError: 9.6549e-7,
},
{order: 6, floatRelError: 1.0084e-5},
{order: 6, floatRelError: 7.3494e-6},
{order: 7, floatRelError: 1.5645e-6},
{order: 8, floatRelError: 8.4828e-7},
{order: 9, floatRelError: 2.3906e-5},
......
third_party/WebKit/LayoutTests/webaudio/AudioBufferSource/audiobuffersource-detune-modulation.html
View file @ 54eca3bd
......@@ -56,8 +56,8 @@
// experiments.
compareBuffersWithConstraints(should, actual, expected, {
prefix: '',
thresholdSNR: 93.337,
thresholdDiffULP: 1.0141,
thresholdSNR: 93.31,
thresholdDiffULP: 1.01,
thresholdDiffCount: 0,
bitDepth: 16
});
......
third_party/WebKit/LayoutTests/webaudio/AudioBufferSource/audiobuffersource-playbackrate-modulation.html
View file @ 54eca3bd
......@@ -55,8 +55,8 @@
// experiments.
compareBuffersWithConstraints(should, actual, expected, {
prefix: 'Verify',
thresholdSNR: 93.274,
thresholdDiffULP: 1.0519,
thresholdSNR: 92.72,
thresholdDiffULP: 0.985,
thresholdDiffCount: 0,
bitDepth: 16
});
......
third_party/WebKit/LayoutTests/webaudio/Oscillator/osc-440hz.html deleted 100644 → 0
View file @ 69e46ae5
<!DOCTYPE html>
<html>
<head>
<title>
Test Custom 440 Hz Oscillator
</title>
<script src="../../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'>let sampleRate = 48000;
// Minimum allowed SNR between the actual oscillator and the expected
// result. Experimentally determined.
let snrThreshold = 59.287;
// Max absolute difference between actual and expected oscillator
// outputs. Experimentally determined.
let maxDiffThreshold = 1.5632e-3;
let audit = Audit.createTaskRunner();
// Test that two ways of creating a 440-Hz sine wave produce the same
// results, within some tolerance.
audit.define('440 Hz Osc', (task, should) => {
// 3-channel context: channel 0 = actual output; channel 1 = expected
// output, channel 2 = difference between channels 0 and 1.
let context = new OfflineAudioContext(3, sampleRate, sampleRate);
let merger = new ChannelMergerNode(
context, {numberOfInputs: context.destination.channelCount});
merger.connect(context.destination);
// Create a 440 Hz oscillator in following way. Use a PeriodicWave with
// a single harmonic value of 440 and use that in an oscillator with
// fundamental frequeqncy of 1 Hz. This should produce a 440 Hz sine
// wave. This is the test signal.
let imag = new Float32Array(512);
imag[440] = 1;
let wave440 =
new PeriodicWave(context, {imag: imag, disableNormaliztion: true});
let oscTest =
new OscillatorNode(context, {frequency: 1, periodicWave: wave440});
// Create a 440 Hz oscillator by specifying a frequency of 440 Hz. We
// use a periodicWave for this so we can disable normalization.
let oscRef = new OscillatorNode(context, {
frequency: 440,
periodocWave: new PeriodicWave(
context, {imag: [0, 1], disableNormaliztion: true})
});
oscTest.connect(merger, 0, 0);
oscRef.connect(merger, 0, 1);
// Compute the difference of the two signals
let neg = new GainNode(context, {gain: -1});
neg.connect(merger, 0, 2);
oscTest.connect(merger, 0, 2);
oscRef.connect(neg);
oscTest.start();
oscRef.start();
context.startRendering()
.then(result => {
// Extract the actual output, the reference output and the
// difference signal from the rendered data.
actual = result.getChannelData(0);
ref = result.getChannelData(1);
diff = result.getChannelData(2);
// The actual and reference signals should be close, and the SNR
// should be high.
should(actual, 'Test oscillator output').beCloseToArray(
ref, {absoluteThreshold: maxDiffThreshold});
let snr = 10 * Math.log10(computeSNR(actual, ref));
should(snr, 'SNR').beGreaterThanOrEqualTo(snrThreshold);
})
.then(() => task.done());
});
audit.run();
</script>
</body>
</html>
third_party/WebKit/LayoutTests/webaudio/Oscillator/osc-sweep-snr-custom.html
View file @ 54eca3bd
......@@ -21,7 +21,7 @@
1, tester.sampleRate * tester.lengthInSeconds, tester.sampleRate);
// The thresholds are experimentally determined.
tester.setThresholds({snr: 139.991, maxDiff: 1.2815e-6});
tester.setThresholds({snr: 140.073, maxDiff: 1.2815e-6});
tester.runTest(
context, 'custom', 'Custom Oscillator with Exponential Sweep', task,
should);
......
third_party/WebKit/LayoutTests/webaudio/Oscillator/osc-sweep-snr-triangle.html
View file @ 54eca3bd
......@@ -21,7 +21,7 @@
1, tester.sampleRate * tester.lengthInSeconds, tester.sampleRate);
// The thresholds are experimentally determined.
tester.setThresholds({snr: 140.51, maxDiff: 1.5423e-6});
tester.setThresholds({snr: 140.51, maxDiff: 1.5386e-6});
tester.runTest(
context, 'triangle', 'Triangle Oscillator with Exponential Sweep ',
task, should);
......
third_party/WebKit/Source/modules/webaudio/OscillatorNode.cpp
View file @ 54eca3bd
......@@ -229,110 +229,6 @@ bool OscillatorHandler::CalculateSampleAccuratePhaseIncrements(
return has_sample_accurate_values;
}
static float DoInterpolation(double virtual_read_index,
float incr,
unsigned read_index_mask,
float table_interpolation_factor,
const float* lower_wave_data,
const float* higher_wave_data) {
DCHECK_GE(incr, 0);
double sample_lower = 0;
double sample_higher = 0;
unsigned read_index_0 = static_cast<unsigned>(virtual_read_index);
// Consider a typical sample rate of 44100 Hz and max periodic wave
// size of 4096. The relationship between |incr| and the frequency
// of the oscillator is |incr| = freq * 4096/44100. Or freq =
// |incr|*44100/4096 = 10.8*|incr|.
//
// For the |incr| thresholds below, this means that we use linear
// interpolation for all freq >= 3.2 Hz, 3-point Lagrange
// for freq >= 1.7 Hz and 5-point Lagrange for every thing else.
//
// We use Lagrange interpolation because it's relatively simple to
// implement and fairly inexpensive, and the interpolator always
// passes through known points.
if (incr >= 0.3) {
// Increment is fairly large, so we're doing no more than about 3
// points between each wave table entry. Assume linear
// interpolation between points is good enough.
unsigned read_index2 = read_index_0 + 1;
// Contain within valid range.
read_index_0 = read_index_0 & read_index_mask;
read_index2 = read_index2 & read_index_mask;
float sample1_lower = lower_wave_data[read_index_0];
float sample2_lower = lower_wave_data[read_index2];
float sample1_higher = higher_wave_data[read_index_0];
float sample2_higher = higher_wave_data[read_index2];
// Linearly interpolate within each table (lower and higher).
double interpolation_factor =
static_cast<float>(virtual_read_index) - read_index_0;
sample_higher = (1 - interpolation_factor) * sample1_higher +
interpolation_factor * sample2_higher;
sample_lower = (1 - interpolation_factor) * sample1_lower +
interpolation_factor * sample2_lower;
} else if (incr >= .16) {
// We're doing about 6 interpolation values between each wave
// table sample. Just use a 3-point Lagrange interpolator to get a
// better estimate than just linear.
//
// See 3-point formula in http://dlmf.nist.gov/3.3#ii
unsigned read_index[3];
for (int k = -1; k <= 1; ++k) {
read_index[k + 1] = (read_index_0 + k) & read_index_mask;
}
double a[3];
double t = virtual_read_index - read_index_0;
a[0] = 0.5 * t * (t - 1);
a[1] = 1 - t * t;
a[2] = 0.5 * t * (t + 1);
for (int k = 0; k < 3; ++k) {
sample_lower += a[k] * lower_wave_data[read_index[k]];
sample_higher += a[k] * higher_wave_data[read_index[k]];
}
} else {
// For everything else (more than 6 points per entry), we'll do a
// 5-point Lagrange interpolator. This is a trade-off between
// quality and speed.
//
// See 5-point formula in http://dlmf.nist.gov/3.3#ii
unsigned read_index[5];
for (int k = -2; k <= 2; ++k) {
read_index[k + 2] = (read_index_0 + k) & read_index_mask;
}
double a[5];
double t = virtual_read_index - read_index_0;
double t2 = t * t;
a[0] = t * (t2 - 1) * (t - 2) / 24;
a[1] = -t * (t - 1) * (t2 - 4) / 6;
a[2] = (t2 - 1) * (t2 - 4) / 4;
a[3] = -t * (t + 1) * (t2 - 4) / 6;
a[4] = t * (t2 - 1) * (t + 2) / 24;
for (int k = 0; k < 5; ++k) {
sample_lower += a[k] * lower_wave_data[read_index[k]];
sample_higher += a[k] * higher_wave_data[read_index[k]];
}
}
// Then interpolate between the two tables.
float sample = (1 - table_interpolation_factor) * sample_higher +
table_interpolation_factor * sample_lower;
return sample;
}
void OscillatorHandler::Process(size_t frames_to_process) {
AudioBus* output_bus = Output(0).Bus();
......@@ -425,6 +321,13 @@ void OscillatorHandler::Process(size_t frames_to_process) {
}
while (n--) {
unsigned read_index = static_cast<unsigned>(virtual_read_index);
unsigned read_index2 = read_index + 1;
// Contain within valid range.
read_index = read_index & read_index_mask;
read_index2 = read_index2 & read_index_mask;
if (has_sample_accurate_values) {
incr = *phase_increments++;
......@@ -434,9 +337,22 @@ void OscillatorHandler::Process(size_t frames_to_process) {
table_interpolation_factor);
}
float sample = DoInterpolation(virtual_read_index, fabs(incr),
read_index_mask, table_interpolation_factor,
lower_wave_data, higher_wave_data);
float sample1_lower = lower_wave_data[read_index];
float sample2_lower = lower_wave_data[read_index2];
float sample1_higher = higher_wave_data[read_index];
float sample2_higher = higher_wave_data[read_index2];
// Linearly interpolate within each table (lower and higher).
float interpolation_factor =
static_cast<float>(virtual_read_index) - read_index;
float sample_higher = (1 - interpolation_factor) * sample1_higher +
interpolation_factor * sample2_higher;
float sample_lower = (1 - interpolation_factor) * sample1_lower +
interpolation_factor * sample2_lower;
// Then interpolate between the two tables.
float sample = (1 - table_interpolation_factor) * sample_higher +
table_interpolation_factor * sample_lower;
*dest_p++ = sample;
......
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