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// META: title=MediaStreamTrackProcessor backpressure tests.
importScripts("/resources/testharness.js");
const height = 240;
const width = 320;
const inputCanvas = new OffscreenCanvas(width, height);
const inputCtx = inputCanvas.getContext('2d', {alpha: false});
inputCtx.fillStyle = 'black';
inputCtx.fillRect(0, 0, width, height);
const frameDuration = 40;
function makeUniformVideoFrame(timestamp) {
return new VideoFrame(inputCanvas, {timestamp, alpha: 'discard'});
}
promise_test(async t => {
const generator = new VideoTrackGenerator();
t.add_cleanup(() => generator.track.stop());
// Write frames for the duration of the test.
const writer = generator.writable.getWriter();
let timestamp = 0;
const intervalId = setInterval(
t.step_func(async () => {
if (generator.readyState === 'live') {
timestamp++;
await writer.write(makeUniformVideoFrame(timestamp));
}
}),
frameDuration);
t.add_cleanup(() => clearInterval(intervalId));
t.step_timeout(function() {
clearInterval(intervalId);
generator.track.stop();
}, 2000);
const processor = new MediaStreamTrackProcessor(generator);
let ts = 1;
await processor.readable.pipeTo(new WritableStream({
async write(frame) {
if (ts === 1) {
assert_equals(frame.timestamp, ts, "Timestamp mismatch");
} else {
assert_greater_than_equal(frame.timestamp, ts, "Backpressure should have resulted in skipping at least 3 frames");
}
frame.close();
ts+=3;
// Wait the equivalent of 3 frames
return new Promise((res) => t.step_timeout(res, 3*frameDuration));
}
}));
}, "Tests that backpressure forces MediaStreamTrackProcess to skip frames");
done();
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