@l5i/dashjs/src/streaming/thumbnail/ThumbnailTracks.js

A reference client implementation for the playback of MPEG DASH via Javascript and compliant browsers.

/**
 * The copyright in this software is being made available under the BSD License,
 * included below. This software may be subject to other third party and contributor
 * rights, including patent rights, and no such rights are granted under this license.
 *
 * Copyright (c) 2013, Dash Industry Forum.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *  * Redistributions of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation and/or
 *  other materials provided with the distribution.
 *  * Neither the name of Dash Industry Forum nor the names of its
 *  contributors may be used to endorse or promote products derived from this software
 *  without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY
 *  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 *  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 *  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 */
import Constants from '../constants/Constants';
import DashConstants from '../../dash/constants/DashConstants';
import FactoryMaker from '../../core/FactoryMaker';
import ThumbnailTrackInfo from '../vo/ThumbnailTrackInfo';
import URLUtils from '../../streaming/utils/URLUtils';
import {replaceIDForTemplate} from '../../dash/utils/SegmentsUtils';

const THUMBNAILS_SCHEME_ID_URIS = ['http://dashif.org/thumbnail_tile',
                                   'http://dashif.org/guidelines/thumbnail_tile'];

function ThumbnailTracks(config) {

    const context = this.context;
    const dashManifestModel = config.dashManifestModel;
    const adapter = config.adapter;
    const baseURLController = config.baseURLController;
    const stream = config.stream;
    const urlUtils = URLUtils(context).getInstance();
    let instance,
        tracks,
        currentTrackIndex;

    function initialize() {
        reset();

        // parse representation and create tracks
        addTracks();
    }

    function addTracks() {
        if (!stream || !dashManifestModel || !adapter) {
            return;
        }

        const streamInfo = stream.getStreamInfo();
        if (!streamInfo) {
            return;
        }

        // Extract thumbnail tracks
        const mediaInfo = adapter.getMediaInfoForType(streamInfo, Constants.IMAGE);
        if (!mediaInfo) {
            return;
        }

        const voAdaptation = adapter.getDataForMedia(mediaInfo);
        if (!voAdaptation) {
            return;
        }

        const voReps = dashManifestModel.getRepresentationsForAdaptation(voAdaptation);
        if (voReps && voReps.length > 0) {
            voReps.forEach((rep) => {
                if (rep.segmentInfoType === DashConstants.SEGMENT_TEMPLATE && rep.segmentDuration > 0 && rep.media)
                createTrack(rep);
            });
        }

        if (tracks.length > 0) {
            // Sort bitrates and select the lowest bitrate rendition
            tracks.sort((a, b) => a.bitrate - b.bitrate);
            currentTrackIndex = tracks.length - 1;
        }
    }

    function createTrack(representation) {
        const track = new ThumbnailTrackInfo();
        track.id = representation.id;
        track.bitrate = representation.bandwidth;
        track.width = representation.width;
        track.height = representation.height;
        track.tilesHor = 1;
        track.tilesVert = 1;
        track.startNumber = representation.startNumber;
        track.segmentDuration = representation.segmentDuration;
        track.timescale = representation.timescale;
        track.templateUrl = buildTemplateUrl(representation);

        if (representation.essentialProperties) {
            representation.essentialProperties.forEach((p) => {
                if (THUMBNAILS_SCHEME_ID_URIS.indexOf(p.schemeIdUri) >= 0 && p.value) {
                    const vars = p.value.split('x');
                    if (vars.length === 2 && !isNaN(vars[0]) && !isNaN(vars[1])) {
                        track.tilesHor = parseInt(vars[0], 10);
                        track.tilesVert = parseInt(vars[1], 10);
                    }
                }
            });
        }
        if (track.tilesHor > 0 && track.tilesVert > 0) {
            // Precalculate width and heigth per tile for perf reasons
            track.widthPerTile = track.width / track.tilesHor;
            track.heightPerTile = track.height / track.tilesVert;
            tracks.push(track);
        }
    }

    function buildTemplateUrl(representation) {
        const templateUrl = urlUtils.isRelative(representation.media) ?
            urlUtils.resolve(representation.media, baseURLController.resolve(representation.path).url) : representation.media;

        if (!templateUrl) {
            return '';
        }

        return replaceIDForTemplate(templateUrl, representation.id);
    }

    function getTracks() {
        return tracks;
    }

    function getCurrentTrackIndex() {
        return currentTrackIndex;
    }

    function getCurrentTrack() {
        if (currentTrackIndex < 0) {
            return null;
        }
        return tracks[currentTrackIndex];
    }

    function setTrackByIndex(index) {
        if (!tracks || tracks.length === 0) {
            return;
        }
        // select highest bitrate in case selected index is higher than bitrate list length
        if (index >= tracks.length) {
            index = tracks.length - 1;
        }
        currentTrackIndex = index;
    }

    function reset() {
        tracks = [];
        currentTrackIndex = -1;
    }

    instance = {
        initialize: initialize,
        getTracks: getTracks,
        reset: reset,
        setTrackByIndex: setTrackByIndex,
        getCurrentTrack: getCurrentTrack,
        getCurrentTrackIndex: getCurrentTrackIndex
    };

    initialize();

    return instance;
}

ThumbnailTracks.__dashjs_factory_name = 'ThumbnailTracks';
export default FactoryMaker.getClassFactory(ThumbnailTracks);