/**
   * Notifies this <tt>Conference</tt> that the ordered list of <tt>Endpoint</tt>s of {@link
   * #speechActivity} i.e. the dominant speaker history has changed.
   *
   * <p>This instance notifies the video <tt>Channel</tt>s about the change so that they may update
   * their last-n lists and report to this instance which <tt>Endpoint</tt>s are to be asked for
   * video keyframes.
   */
  private void speechActivityEndpointsChanged() {
    List<Endpoint> endpoints = null;

    for (Content content : getContents()) {
      if (MediaType.VIDEO.equals(content.getMediaType())) {
        Set<Endpoint> endpointsToAskForKeyframes = null;

        endpoints = speechActivity.getEndpoints();
        for (Channel channel : content.getChannels()) {
          if (!(channel instanceof RtpChannel)) continue;

          RtpChannel rtpChannel = (RtpChannel) channel;
          List<Endpoint> channelEndpointsToAskForKeyframes =
              rtpChannel.speechActivityEndpointsChanged(endpoints);

          if ((channelEndpointsToAskForKeyframes != null)
              && !channelEndpointsToAskForKeyframes.isEmpty()) {
            if (endpointsToAskForKeyframes == null) {
              endpointsToAskForKeyframes = new HashSet<>();
            }
            endpointsToAskForKeyframes.addAll(channelEndpointsToAskForKeyframes);
          }
        }

        if ((endpointsToAskForKeyframes != null) && !endpointsToAskForKeyframes.isEmpty()) {
          content.askForKeyframes(endpointsToAskForKeyframes);
        }
      }
    }
  }
 /**
  * Adds <tt>WebRtcDataStreamListener</tt> to the list of listeners.
  *
  * @param listener the <tt>WebRtcDataStreamListener</tt> to be added to the listeners list.
  */
 public void addChannelListener(WebRtcDataStreamListener listener) {
   if (listener == null) {
     throw new NullPointerException("listener");
   } else {
     synchronized (listeners) {
       if (!listeners.contains(listener)) {
         listeners.add(listener);
       }
     }
   }
 }
  /**
   * Expires a specific <tt>Content</tt> of this <tt>Conference</tt> (i.e. if the specified
   * <tt>content</tt> is not in the list of <tt>Content</tt>s of this <tt>Conference</tt>, does
   * nothing).
   *
   * @param content the <tt>Content</tt> to be expired by this <tt>Conference</tt>
   */
  public void expireContent(Content content) {
    boolean expireContent;

    synchronized (contents) {
      if (contents.contains(content)) {
        contents.remove(content);
        expireContent = true;
      } else expireContent = false;
    }
    if (expireContent) content.expire();
  }
  /**
   * Gets the <tt>WebRtcDataStreamListener</tt>s added to this instance.
   *
   * @return the <tt>WebRtcDataStreamListener</tt>s added to this instance or <tt>null</tt> if there
   *     are no <tt>WebRtcDataStreamListener</tt>s added to this instance
   */
  private WebRtcDataStreamListener[] getChannelListeners() {
    WebRtcDataStreamListener[] ls;

    synchronized (listeners) {
      if (listeners.isEmpty()) {
        ls = null;
      } else {
        ls = listeners.toArray(new WebRtcDataStreamListener[listeners.size()]);
      }
    }
    return ls;
  }
 /**
  * Removes <tt>WebRtcDataStreamListener</tt> from the list of listeners.
  *
  * @param listener the <tt>WebRtcDataStreamListener</tt> to be removed from the listeners list.
  */
 public void removeChannelListener(WebRtcDataStreamListener listener) {
   if (listener != null) {
     synchronized (listeners) {
       listeners.remove(listener);
     }
   }
 }
  /**
   * Gets the <tt>Endpoint</tt>s participating in/contributing to this <tt>Conference</tt>.
   *
   * @return the <tt>Endpoint</tt>s participating in/contributing to this <tt>Conference</tt>
   */
  public List<Endpoint> getEndpoints() {
    List<Endpoint> endpoints;
    boolean changed = false;

    synchronized (this.endpoints) {
      endpoints = new ArrayList<>(this.endpoints.size());
      for (Iterator<WeakReference<Endpoint>> i = this.endpoints.iterator(); i.hasNext(); ) {
        Endpoint endpoint = i.next().get();

        if (endpoint == null) {
          i.remove();
          changed = true;
        } else {
          endpoints.add(endpoint);
        }
      }
    }

    if (changed) firePropertyChange(ENDPOINTS_PROPERTY_NAME, null, null);

    return endpoints;
  }
  /**
   * Gets a <tt>Content</tt> of this <tt>Conference</tt> which has a specific name. If a
   * <tt>Content</tt> of this <tt>Conference</tt> with the specified <tt>name</tt> does not exist at
   * the time the method is invoked, the method initializes a new <tt>Content</tt> instance with the
   * specified <tt>name</tt> and adds it to the list of <tt>Content</tt>s of this
   * <tt>Conference</tt>.
   *
   * @param name the name of the <tt>Content</tt> which is to be returned
   * @return a <tt>Content</tt> of this <tt>Conference</tt> which has the specified <tt>name</tt>
   */
  public Content getOrCreateContent(String name) {
    Content content;

    synchronized (contents) {
      for (Content aContent : contents) {
        if (aContent.getName().equals(name)) {
          aContent.touch(); // It seems the content is still active.
          return aContent;
        }
      }

      content = new Content(this, name);
      if (isRecording()) {
        content.setRecording(true, getRecordingPath());
      }
      contents.add(content);
    }

    if (logger.isInfoEnabled()) {
      /*
       * The method Videobridge.getChannelCount() should better be
       * executed outside synchronized blocks in order to reduce the risks
       * of causing deadlocks.
       */
      Videobridge videobridge = getVideobridge();

      logger.info(
          "Created content "
              + name
              + " of conference "
              + getID()
              + ". "
              + videobridge.getConferenceCountString());
    }

    return content;
  }
 /**
  * Gets the <tt>Content</tt>s of this <tt>Conference</tt>.
  *
  * @return the <tt>Content</tt>s of this <tt>Conference</tt>
  */
 public Content[] getContents() {
   synchronized (contents) {
     return contents.toArray(new Content[contents.size()]);
   }
 }