rx-player/src/transports/dash/get_events_out_of_emsgs.ts

Canal+ HTML5 Video Player

/**
 * Copyright 2015 CANAL+ Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import type { IInbandEvent } from "../../core/types";
import type { IEMSG } from "../../parsers/containers/isobmff";
import { utf8ToStr } from "../../utils/string_parsing";

/**
 * From an array of EMSGs with manifest validity scheme id,
 * tells if the manifest needs to be refreshed.
 * @param {Array.<Object>} emsgs
 * @param {number} manifestPublishTime
 * @returns {boolean}
 */
function manifestNeedsToBeRefreshed(
  emsgs: IEMSG[],
  manifestPublishTime: number,
): boolean {
  if (emsgs.length <= 0) {
    return false;
  }
  const len = emsgs.length;
  for (let i = 0; i < len; i++) {
    const manifestRefreshEventFromEMSGs = emsgs[i];
    const currentManifestPublishTime = manifestPublishTime;
    const { messageData } = manifestRefreshEventFromEMSGs;
    const strPublishTime = utf8ToStr(messageData);
    const eventManifestPublishTime = Date.parse(strPublishTime);
    if (
      currentManifestPublishTime === undefined ||
      eventManifestPublishTime === undefined ||
      isNaN(eventManifestPublishTime) ||
      // DASH-if 4.3 tells (4.5.2.1) :
      // "The media presentation time beyond the event time (indicated
      // time by presentation_time_delta) is correctly described only
      // by MPDs with publish time greater than indicated value in the
      // message_data field."
      //
      // Here, if the current manifest has its publish time inferior or
      // identical to the event manifest publish time, then the manifest needs
      // to be updated
      eventManifestPublishTime >= currentManifestPublishTime
    ) {
      return true;
    }
  }
  return false;
}

/**
 * Get wrapped inband events and manifest refresh event from
 * parsed ISOBMFF EMSG boxes.
 * @param {Array.<Object>} parsedEMSGs
 * @param {undefined | number} manifestPublishTime
 * @returns {Object}
 */
export default function getEventsOutOfEMSGs(
  parsedEMSGs: IEMSG[],
  manifestPublishTime?: number,
):
  | { needsManifestRefresh: boolean; inbandEvents: IInbandEvent[] | undefined }
  | undefined {
  if (parsedEMSGs.length === 0) {
    return undefined;
  }
  const { manifestRefreshEventsFromEMSGs, EMSGs } = parsedEMSGs.reduce(
    (acc, val: IEMSG) => {
      // Scheme that signals manifest update
      if (
        val.schemeIdUri === "urn:mpeg:dash:event:2012" &&
        // TODO support value 2 and 3
        val.value === "1"
      ) {
        if (acc.manifestRefreshEventsFromEMSGs === undefined) {
          acc.manifestRefreshEventsFromEMSGs = [];
        }
        acc.manifestRefreshEventsFromEMSGs.push(val);
      } else {
        if (acc.EMSGs === undefined) {
          acc.EMSGs = [];
        }
        acc.EMSGs.push(val);
      }
      return acc;
    },
    {
      manifestRefreshEventsFromEMSGs: undefined as IEMSG[] | undefined,
      EMSGs: undefined as IEMSG[] | undefined,
    },
  );
  const inbandEvents = EMSGs?.map((evt) => ({
    type: "emsg" as const,
    value: evt,
  }));
  const needsManifestRefresh =
    manifestPublishTime === undefined || manifestRefreshEventsFromEMSGs === undefined
      ? false
      : manifestNeedsToBeRefreshed(manifestRefreshEventsFromEMSGs, manifestPublishTime);
  return { inbandEvents, needsManifestRefresh };
}