rx-player/src/core/stream/representation/utils/get_segment_priority.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 config from "../../../../config";

/**
 * Calculate the priority number for a given segment start time, in function of
 * the distance with the wanted starting timestamp.
 *
 * The lower is this number, the higher should be the priority of the request.
 *
 * Note that a `segmentTime` given behind the current time will always have the
 * highest priority.
 * @param {number} segmentTime
 * @param {Object} wantedStartTimestamp
 * @returns {number}
 */
export default function getSegmentPriority(
  segmentTime: number,
  wantedStartTimestamp: number,
): number {
  const distance = segmentTime - wantedStartTimestamp;
  const { SEGMENT_PRIORITIES_STEPS } = config.getCurrent();
  for (let priority = 0; priority < SEGMENT_PRIORITIES_STEPS.length; priority++) {
    if (distance < SEGMENT_PRIORITIES_STEPS[priority]) {
      return priority;
    }
  }
  return SEGMENT_PRIORITIES_STEPS.length;
}