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<!doctype html>
<meta charset=utf-8>
<meta name="timeout" content="long">
<title>RTCRtpSendParameters degradationPreference effect</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../webrtc/RTCPeerConnection-helper.js"></script>
<script>
'use strict';
// This file contains tests that check that degradation preference
// actually has the desired effect. These tests take a long time to run.
// The signal generator will generate a video stream with at least this
// many bits per second if unconstrained.
const minUnconstrainedBandwidth = 30000;
// Returns incoming bandwidth usage between stats1 and stats2
// in bits per second.
function bandwidth(stats1, stats2) {
if (!stats1 || !stats2) {
return null;
}
const transport1 = [...stats1.values()].filter(({type}) => type === 'transport')[0];
const transport2 = [...stats2.values()].filter(({type}) => type === 'transport')[0];
const bytes = transport2.bytesReceived - transport1.bytesReceived;
// If time interval is too short for proper measurement, return null.
if (transport1.timestamp > transport2.timestamp - 100) {
return null;
}
// Multiply by 1000 to get per second, multiply by 8 to get bits.
const bandwidth = 1000 * 8 * bytes /
(transport2.timestamp - transport1.timestamp);
return bandwidth;
}
let oldStats;
// Returns tuple of { bandwidth, fps, x-res, y-res }
// Updates oldStats.
async function measureStuff(pc) {
const stats = await pc.getStats();
if (!oldStats) {
oldStats = stats;
return {};
}
// RTCInboundStreamStats
const oldRtpList = [...oldStats.values()].filter(({type}) => type === 'inbound-rtp');
const inboundRtpList = [...stats.values()].filter(({type}) => type === 'inbound-rtp');
const oldRtp = oldRtpList[0];
const inboundRtp = inboundRtpList[0];
const fps = 1000.0 * (inboundRtp.framesReceived - oldRtp.framesReceived) /
(inboundRtp.timestamp - oldRtp.timestamp);
const result = {
bandwidth: bandwidth(oldStats, stats),
fps: fps,
width: inboundRtp.frameWidth,
height: inboundRtp.frameHeight
};
oldStats = stats;
if (!result.bandwidth) {
return {};
}
// Unbreak for debugging.
// con sole.log('Measure: ', performance.now(), " ", JSON.stringify(result));
return result;
}
promise_test(async t => {
const pc1 = new RTCPeerConnection();
t.add_cleanup(() => pc1.close());
const stream = await getNoiseStream({video: true});
t.add_cleanup(() => stream.getTracks().forEach(track => track.stop()));
const track = stream.getTracks()[0];
const { sender } = pc1.addTransceiver(track);
let param = sender.getParameters();
param.degradationPreference = 'maintain-framerate';
await sender.setParameters(param);
const pc2 = new RTCPeerConnection();
t.add_cleanup(() => pc2.close());
exchangeIceCandidates(pc1, pc2);
await exchangeOfferAnswer(pc1, pc2);
await listenToConnected(pc1);
// Allow the keyframe to pass.
await new Promise(r => t.step_timeout(r, 1000));
// Wait a few seconds to allow things to settle (rampup)
// We know that the generator is supposed to produce 640x480
// at 10 fps with a bandwidth exceeding 30 kbits/second.
await t.step_wait(async () => {
const measure = await measureStuff(pc2);
return (measure.bandwidth > minUnconstrainedBandwidth &&
measure.width == 640 &&
measure.fps > 9);
}, 'Test error: Preconditions not achieved', 30000, 500);
// Measure BW, resolution and frame rate over one second
// after measurements have stabilized.
await new Promise(r => t.step_timeout(r, 1000));
const stats1 = await measureStuff(pc2);
// Constrain BW to 1/2 of measured value
const newBandwidth = stats1.bandwidth / 2;
// Guard against inappropriate bandwidth
assert_greater_than(newBandwidth, minUnconstrainedBandwidth/2,
"Test error: Constraint too low");
const parameters = sender.getParameters();
parameters.encodings[0].maxBitrate = newBandwidth;
await sender.setParameters(parameters);
// Wait until the expected result happens.
const kBandwidthMargin = 1.3;
// It takes time to adapt to a new bandwidth, time to scale down,
// and time to acknowledge that framerate should not be reduced.
// Measured time is around 16 seconds.
await t.step_wait(async () => {
let measure = await measureStuff(pc2);
return (measure.bandwidth &&
measure.bandwidth < newBandwidth * kBandwidthMargin &&
measure.width < stats1.width &&
measure.fps > stats1.fps * 0.9);
}, 'Adaptation did not succeed',
30000, 500);
}, 'Maintain-framerate reduces resolution on bandwidth cut', { timeout: 35000 });
</script>
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