mirror of
https://github.com/classilla/tenfourfox.git
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73 lines
2.4 KiB
HTML
73 lines
2.4 KiB
HTML
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<!DOCTYPE html>
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<title>Test seamless playback of a series of resampled buffers</title>
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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<script>
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// Permitting some accumulation of rounding to int16_t.
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// 64/2^15 would be only just small enough to detect off-by-one-subsample
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// scheduling errors with the frequencies here.
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const EPSILON = 4.0 / Math.pow(2, 15);
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// Offsets test for rounding to nearest rather than up or down.
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const OFFSETS = [EPSILON, 1.0 - EPSILON];
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// The ratio of resampling is 147:160, so 256 start points is enough to cover
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// every fractional offset.
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const LENGTH = 256;
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function do_test(context_rate, buffer_rate, start_offset) {
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var context =
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new OfflineAudioContext(2, LENGTH, context_rate);
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var merger = context.createChannelMerger(context.destination.channelCount);
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merger.connect(context.destination);
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// Create an audio signal that will be repeated
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var repeating_signal = context.createBuffer(1, 1, buffer_rate);
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repeating_signal.getChannelData(0)[0] = 0.5;
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// Schedule a series of nodes to repeat the signal.
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for (var i = 0; i < LENGTH; ++i) {
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var source = context.createBufferSource();
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source.buffer = repeating_signal;
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source.connect(merger, 0, 0);
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source.start((i + start_offset) / buffer_rate);
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}
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// A single long signal should produce the same result.
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var long_signal = context.createBuffer(1, LENGTH, buffer_rate);
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var c = long_signal.getChannelData(0);
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for (var i = 0; i < c.length; ++i) {
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c[i] = 0.5;
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}
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var source = context.createBufferSource();
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source.buffer = long_signal;
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source.connect(merger, 0, 1);
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source.start(start_offset / buffer_rate);
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return context.startRendering().
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then((buffer) => {
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series_output = buffer.getChannelData(0);
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expected = buffer.getChannelData(1);
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for (var i = 0; i < buffer.length; ++i) {
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assert_approx_equals(series_output[i], expected[i], EPSILON,
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"series output at " + i);
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}
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});
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}
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function start_tests(context_rate, buffer_rate) {
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OFFSETS.forEach((start_offset) => {
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promise_test(() => do_test(context_rate, buffer_rate, start_offset),
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"" + context_rate + " context, "
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+ buffer_rate + " buffer, "
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+ start_offset + " start");
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});
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}
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start_tests(48000, 44100);
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start_tests(44100, 48000);
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</script>
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