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<!DOCTYPE html>
<html>
<head>
<title>audiochannelmerger-input.html</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/merger-testing.js"></script>
</head>
<body>
<script>
promise_test((t) => {
// Task: Check if an inactive input renders a silent mono channel in the
// output.
return testMergerInput_W3CTH({
numberOfChannels: 6,
// Create a mono source buffer filled with '1'.
testBufferContent: [1],
// Connect the output of source into the 4th input of merger.
mergerInputIndex: 3,
// All channels should contain 0, except channel 4 which should be 1.
expected: [0, 0, 0, 1, 0, 0],
});
}, 'Silent inactive inputs produce 0 in unused merger channels');
promise_test((t) => {
// Task: Check if a stereo input is being down-mixed to mono channel
// correctly based on the mixing rule.
return testMergerInput_W3CTH({
numberOfChannels: 6,
// Create a stereo buffer filled with '1' and '2' for left and right
// channels respectively.
testBufferContent: [1, 2],
// Connect the output of source into the 1st input of merger.
mergerInputIndex: undefined,
// The result of summed and down-mixed stereo audio should be 1.5.
// (= 1 * 0.5 + 2 * 0.5)
expected: [1.5, 0, 0, 0, 0, 0],
});
}, 'Stereo input should down-mix properly to mono merger input');
promise_test((t) => {
// Task: Check if 3-channel input gets processed by the 'discrete'
// mixing rule.
return testMergerInput_W3CTH({
numberOfChannels: 6,
// Create a 3-channel buffer filled with '1', '2', and '3'
// respectively.
testBufferContent: [1, 2, 3],
// Connect the output of source into the 1st input of merger.
mergerInputIndex: undefined,
// The result of summed stereo audio should be 1 because 3-channel is
// not a canonical layout, so the input channel 2 and 3 should be
// dropped by 'discrete' mixing rule.
expected: [1, 0, 0, 0, 0, 0],
});
}, '3-channel input uses discrete rule, dropping 2nd and 3rd channels');
promise_test((t) => {
// Task: Merging two inputs into a single stereo stream.
// For this test, the number of channel should be 2.
const context = new OfflineAudioContext(2, 128, 44100);
const merger = context.createChannelMerger();
const source1 = context.createBufferSource();
const source2 = context.createBufferSource();
// Create a DC offset buffer (mono) filled with 1 and assign it to BS
// nodes.
const positiveDCOffset = createConstantBuffer(context, 128, 1);
const negativeDCOffset = createConstantBuffer(context, 128, -1);
source1.buffer = positiveDCOffset;
source2.buffer = negativeDCOffset;
// Connect: BS#1 => merger_input#0, BS#2 => Inverter => merger_input#1
source1.connect(merger, 0, 0);
source2.connect(merger, 0, 1);
merger.connect(context.destination);
source1.start();
source2.start();
return context.startRendering().then((buffer) => {
assert_array_equals(
buffer.getChannelData(0),
new Float32Array(128).fill(1),
'Channel #0 should be constant value of 1');
assert_array_equals(
buffer.getChannelData(1),
new Float32Array(128).fill(-1),
'Channel #1 should be constant value of -1');
});
}, 'Merging two mono sources into stereo using ChannelMerger');
</script>
</body>
</html>