| <!doctype html> |
| <html> |
| <head> |
| <title>MediaStreamTrackProcessor backpressure</title> |
| <link rel="help" href="https://w3c.github.io/mediacapture-insertable-streams"> |
| </head> |
| <body> |
| <h1 class="instructions">Description</h1> |
| <p class="instructions">This test checks that MediaStreamTrackProcessor handles backpressure from a WHATWG stream pipeline.</p> |
| <script src=/resources/testharness.js></script> |
| <script src=/resources/testharnessreport.js></script> |
| <script src=/resources/testdriver.js></script> |
| <script src=/resources/testdriver-vendor.js></script> |
| <script> |
| |
| 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 => { |
| // TODO: use "new VideoTrackGenerator" |
| const generator = new MediaStreamTrackGenerator({kind: 'video'}); |
| t.add_cleanup(() => generator.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.stop(); |
| }, 2000); |
| const processor = new MediaStreamTrackProcessor({track: 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"); |
| </script> |
| </body> |
| </html> |
