AudioVisualElementSelector.java

/**
 * Licensed to The Apereo Foundation under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 *
 * The Apereo Foundation licenses this file to you under the Educational
 * Community 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://opensource.org/licenses/ecl2.txt
 *
 * 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.
 *
 */

package org.opencastproject.mediapackage.selector;

import org.opencastproject.mediapackage.MediaPackage;
import org.opencastproject.mediapackage.MediaPackageElementFlavor;
import org.opencastproject.mediapackage.Track;

import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

/**
 * This <code>MediaPackageElementSelector</code> selects a combination of tracks from a <code>MediaPackage</code> that
 * contain audio and video stream.
 */
public class AudioVisualElementSelector extends AbstractMediaPackageElementSelector<Track> {

  /** Explicit video flavor */
  protected MediaPackageElementFlavor videoFlavor = null;

  /** Explicit audio flavor */
  protected MediaPackageElementFlavor audioFlavor = null;

  /** The resulting audio track */
  protected Track audioTrack = null;

  /** The resulting video track */
  protected Track videoTrack = null;

  /** Flag to indicate whether an audio track is required */
  protected boolean requireAudio = false;

  /** Flag to indicate whether a video track is required */
  protected boolean requireVideo = false;

  /**
   * Creates a new selector.
   */
  public AudioVisualElementSelector() {
  }

  /**
   * Creates a new selector that will restrict the result of <code>select()</code> to the given flavor.
   *
   * @param flavor
   *          the flavor
   */
  public AudioVisualElementSelector(String flavor) {
    this(MediaPackageElementFlavor.parseFlavor(flavor));
  }

  /**
   * Creates a new selector that will restrict the result of <code>select()</code> to the given flavor.
   *
   * @param flavor
   *          the flavor
   */
  public AudioVisualElementSelector(MediaPackageElementFlavor flavor) {
    addFlavor(flavor);
  }

  /**
   * Specifies an explicit audio flavor.
   *
   * @param flavor
   *          the flavor
   */
  public void setAudioFlavor(String flavor) {
    if (flavor == null) {
      audioFlavor = null;
    } else {
      setAudioFlavor(MediaPackageElementFlavor.parseFlavor(flavor));
    }
  }

  /**
   * Specifies an explicit audio flavor.
   *
   * @param flavor
   *          the flavor
   */
  public void setAudioFlavor(MediaPackageElementFlavor flavor) {
    if (flavor != null)
      addFlavor(flavor);
    audioFlavor = flavor;
  }

  /**
   * If set to <code>true</code>, this selector requires an audio track to be part of the result set, or a video track
   * containing at least one audio stream.
   *
   * @param require
   *          <code>true</code> to require an audio track
   */
  public void setRequireAudioTrack(boolean require) {
    requireAudio = require;
  }

  /**
   * If set to <code>true</code>, this selector requires a video track to be part of the result set.
   *
   * @param require
   *          <code>true</code> to require a video track
   */
  public void setRequireVideoTrack(boolean require) {
    requireVideo = require;
  }

  /**
   * Returns the explicit audio flavor or <code>null</code> if none was specified.
   *
   * @return the audio flavor
   */
  public MediaPackageElementFlavor getAudioFlavor() {
    return audioFlavor;
  }

  /**
   * Specifies an explicit video flavor.
   *
   * @param flavor
   *          the flavor
   */
  public void setVideoFlavor(String flavor) {
    if (flavor == null) {
      videoFlavor = null;
    } else {
      setVideoFlavor(MediaPackageElementFlavor.parseFlavor(flavor));
    }
  }

  /**
   * Specifies an explicit video flavor.
   *
   * @param flavor
   *          the flavor
   */
  public void setVideoFlavor(MediaPackageElementFlavor flavor) {
    if (flavor != null)
      addFlavor(flavor);
    videoFlavor = flavor;
  }

  /**
   * Returns the explicit video flavor or <code>null</code> if none was specified.
   *
   * @return the video flavor
   */
  public MediaPackageElementFlavor getVideoFlavor() {
    return videoFlavor;
  }

  /**
   * Returns the audio track that has been selected by a call to {@link #select(MediaPackage, boolean)}, which might be
   * <code>null</code> if no audio is required or available.
   *
   * @return the audio track
   */
  public Track getAudioTrack() {
    return audioTrack;
  }

  /**
   * Returns the video track that has been selected by a call to {@link #select(MediaPackage, boolean)}, which might be
   * <code>null</code> if no video is required or available.
   *
   * @return the video track
   */
  public Track getVideoTrack() {
    return videoTrack;
  }

  /**
   * Returns a track or a number of tracks from the media package that together contain audio and video. If no such
   * combination can be found, e. g. there is no audio or video at all, an empty array is returned.
   *
   * @see org.opencastproject.mediapackage.selector.AbstractMediaPackageElementSelector#select(org.opencastproject.mediapackage.MediaPackage, boolean)
   */
  @Override
  public Collection<Track> select(MediaPackage mediaPackage, boolean withTagsAndFlavors) {
    Collection<Track> candidates = super.select(mediaPackage, withTagsAndFlavors);
    Set<Track> result = new HashSet<Track>();

    boolean foundAudio = false;
    boolean foundVideo = false;

    // Try to look for the perfect match: a track containing audio and video
    for (Track t : candidates) {
      if (audioFlavor == null && videoFlavor == null) {
        foundAudio |= t.hasAudio();
        foundVideo |= t.hasVideo();
        result.add(t);
      } else {
        if (audioFlavor != null && t.hasAudio() && audioFlavor.matches(t.getFlavor())
                && !(videoFlavor == null && t.hasVideo())) {
          foundAudio = true;
          audioTrack = t;
          result.add(t);
        }
        if (videoFlavor != null && t.hasVideo() && videoFlavor.matches(t.getFlavor())
                && !(audioFlavor == null && t.hasAudio())) {
          foundVideo = true;
          videoTrack = t;
          result.add(t);
        }
      }
      if ((foundAudio || audioFlavor == null) && (foundVideo || videoFlavor == null))
        break;
    }

    if ((!foundAudio && requireAudio) || (!foundVideo && requireVideo))
      result.clear();

    // We were lucky, a combination was found!
    return result;
  }

}