twilio-video/es5/media/track/capturevideoframes.js

Twilio Video JavaScript Library

/* globals MediaStreamTrackGenerator, MediaStreamTrackProcessor, TransformStream */
'use strict';
const { DEFAULT_FRAME_RATE } = require('../../util/constants');
function captureVideoFramesSetInterval(videoEl, processVideoFrame) {
    const [track] = videoEl.srcObject.getVideoTracks();
    const { frameRate = DEFAULT_FRAME_RATE } = track.getSettings();
    let sampleInterval;
    const readable = new ReadableStream({
        start(controller) {
            sampleInterval = setInterval(() => controller.enqueue(), 1000 / frameRate);
        }
    });
    const transformer = new TransformStream({
        transform() {
            return processVideoFrame();
        }
    });
    readable
        .pipeThrough(transformer)
        .pipeTo(new WritableStream())
        .then(() => { });
    return () => {
        clearInterval(sampleInterval);
    };
}
function captureVideoFramesInsertableStreams(videoEl, processVideoFrame, videoFrameType) {
    const [track] = videoEl.srcObject.getVideoTracks();
    const { readable } = new MediaStreamTrackProcessor({ track });
    const generator = new MediaStreamTrackGenerator({ kind: 'video' });
    let shouldStop = false;
    const transformer = new TransformStream({
        transform(videoFrame, controller) {
            const promise = videoFrameType === 'videoframe'
                ? processVideoFrame(videoFrame)
                : Promise.resolve(videoFrame.close())
                    .then(processVideoFrame);
            return promise.finally(() => {
                if (shouldStop) {
                    controller.terminate();
                }
            });
        }
    });
    readable
        .pipeThrough(transformer)
        .pipeTo(generator.writable)
        .then(() => { });
    return () => {
        shouldStop = true;
    };
}
module.exports = typeof MediaStreamTrackGenerator === 'function' && typeof MediaStreamTrackProcessor === 'function'
    ? captureVideoFramesInsertableStreams
    : captureVideoFramesSetInterval;
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