/**
     * Function called when an audio device is plugged or unplugged.
     *
     * @param event The property change event which may concern the audio device.
     */
    public void propertyChange(PropertyChangeEvent event) {
      if (DeviceConfiguration.PROP_AUDIO_SYSTEM_DEVICES.equals(event.getPropertyName())) {
        NotificationService notificationService = getNotificationService();

        if (notificationService != null) {
          // Registers only once to the  popup message notification
          // handler.
          if (!isRegisteredToPopupMessageListener) {
            isRegisteredToPopupMessageListener = true;
            managePopupMessageListenerRegistration(true);
          }

          // Fires the popup notification.
          ResourceManagementService resources = NeomediaActivator.getResources();
          Map<String, Object> extras = new HashMap<String, Object>();

          extras.put(NotificationData.POPUP_MESSAGE_HANDLER_TAG_EXTRA, this);
          notificationService.fireNotification(
              DEVICE_CONFIGURATION_HAS_CHANGED,
              resources.getI18NString("impl.media.configform" + ".AUDIO_DEVICE_CONFIG_CHANGED"),
              resources.getI18NString(
                  "impl.media.configform" + ".AUDIO_DEVICE_CONFIG_MANAGMENT_CLICK"),
              null,
              extras);
        }
      }
    }
  /**
   * Returns the sequence number to use for a specific RTX packet, which is based on the packet's
   * original sequence number.
   *
   * <p>Because we terminate the RTX format, and with simulcast we might translate RTX packets from
   * multiple SSRCs into the same SSRC, we keep count of the RTX packets (and their sequence
   * numbers) which we sent for each SSRC.
   *
   * @param ssrc the SSRC of the RTX stream for the packet.
   * @param defaultSeq the default sequence number to use in case we don't (yet) have any
   *     information about <tt>ssrc</tt>.
   * @return the sequence number which should be used for the next RTX packet sent using SSRC
   *     <tt>ssrc</tt>.
   */
  private int getNextRtxSequenceNumber(long ssrc, int defaultSeq) {
    Integer seq;
    synchronized (rtxSequenceNumbers) {
      seq = rtxSequenceNumbers.get(ssrc);
      if (seq == null) seq = defaultSeq;
      else seq++;

      rtxSequenceNumbers.put(ssrc, seq);
    }

    return seq;
  }
  /**
   * Returns the sequence number to use for a specific RTX packet, which is based on the packet's
   * original sequence number.
   *
   * <p>Because we terminate the RTX format, and with simulcast we might translate RTX packets from
   * multiple SSRCs into the same SSRC, we keep count of the RTX packets (and their sequence
   * numbers) which we sent for each SSRC.
   *
   * @param ssrc the SSRC of the RTX stream for the packet.
   * @return the sequence number which should be used for the next RTX packet sent using SSRC
   *     <tt>ssrc</tt>.
   */
  private int getNextRtxSequenceNumber(long ssrc) {
    Integer seq;
    synchronized (rtxSequenceNumbers) {
      seq = rtxSequenceNumbers.get(ssrc);
      if (seq == null) seq = new Random().nextInt(0xffff);
      else seq++;

      rtxSequenceNumbers.put(ssrc, seq);
    }

    return seq;
  }
  /**
   * Returns, the <tt>TransportManager</tt> instance for the channel-bundle with ID
   * <tt>channelBundleId</tt>. If no instance exists and <tt>create</tt> is <tt>true</tt>, one will
   * be created.
   *
   * @param channelBundleId the ID of the channel-bundle for which to return the
   *     <tt>TransportManager</tt>.
   * @param create whether to create a new instance, if one doesn't exist.
   * @return the <tt>TransportManager</tt> instance for the channel-bundle with ID
   *     <tt>channelBundleId</tt>.
   */
  IceUdpTransportManager getTransportManager(String channelBundleId, boolean create) {
    IceUdpTransportManager transportManager;

    synchronized (transportManagers) {
      transportManager = transportManagers.get(channelBundleId);
      if (transportManager == null && create && !isExpired()) {
        try {
          // FIXME: the initiator is hard-coded
          // We assume rtcp-mux when bundle is used, so we make only
          // one component.
          transportManager = new IceUdpTransportManager(this, true, 1);
        } catch (IOException ioe) {
          throw new UndeclaredThrowableException(ioe);
        }
        transportManagers.put(channelBundleId, transportManager);
      }
    }

    return transportManager;
  }
  /**
   * Opens new WebRTC data channel using specified parameters.
   *
   * @param type channel type as defined in control protocol description. Use 0 for "reliable".
   * @param prio channel priority. The higher the number, the lower the priority.
   * @param reliab Reliability Parameter<br>
   *     This field is ignored if a reliable channel is used. If a partial reliable channel with
   *     limited number of retransmissions is used, this field specifies the number of
   *     retransmissions. If a partial reliable channel with limited lifetime is used, this field
   *     specifies the maximum lifetime in milliseconds. The following table summarizes this:<br>
   *     </br>
   *     <p>+------------------------------------------------+------------------+ | Channel Type |
   *     Reliability | | | Parameter |
   *     +------------------------------------------------+------------------+ |
   *     DATA_CHANNEL_RELIABLE | Ignored | | DATA_CHANNEL_RELIABLE_UNORDERED | Ignored | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT | Number of RTX | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED | Number of RTX | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_TIMED | Lifetime in ms | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED | Lifetime in ms |
   *     +------------------------------------------------+------------------+
   * @param sid SCTP stream id that will be used by new channel (it must not be already used).
   * @param label text label for the channel.
   * @return new instance of <tt>WebRtcDataStream</tt> that represents opened WebRTC data channel.
   * @throws IOException if IO error occurs.
   */
  public synchronized WebRtcDataStream openChannel(
      int type, int prio, long reliab, int sid, String label) throws IOException {
    if (channels.containsKey(sid)) {
      throw new IOException("Channel on sid: " + sid + " already exists");
    }

    // Label Length & Label
    byte[] labelBytes;
    int labelByteLength;

    if (label == null) {
      labelBytes = null;
      labelByteLength = 0;
    } else {
      labelBytes = label.getBytes("UTF-8");
      labelByteLength = labelBytes.length;
      if (labelByteLength > 0xFFFF) labelByteLength = 0xFFFF;
    }

    // Protocol Length & Protocol
    String protocol = WEBRTC_DATA_CHANNEL_PROTOCOL;
    byte[] protocolBytes;
    int protocolByteLength;

    if (protocol == null) {
      protocolBytes = null;
      protocolByteLength = 0;
    } else {
      protocolBytes = protocol.getBytes("UTF-8");
      protocolByteLength = protocolBytes.length;
      if (protocolByteLength > 0xFFFF) protocolByteLength = 0xFFFF;
    }

    ByteBuffer packet = ByteBuffer.allocate(12 + labelByteLength + protocolByteLength);

    // Message open new channel on current sid
    // Message Type
    packet.put((byte) MSG_OPEN_CHANNEL);
    // Channel Type
    packet.put((byte) type);
    // Priority
    packet.putShort((short) prio);
    // Reliability Parameter
    packet.putInt((int) reliab);
    // Label Length
    packet.putShort((short) labelByteLength);
    // Protocol Length
    packet.putShort((short) protocolByteLength);
    // Label
    if (labelByteLength != 0) {
      packet.put(labelBytes, 0, labelByteLength);
    }
    // Protocol
    if (protocolByteLength != 0) {
      packet.put(protocolBytes, 0, protocolByteLength);
    }

    int sentCount = sctpSocket.send(packet.array(), true, sid, WEB_RTC_PPID_CTRL);

    if (sentCount != packet.capacity()) {
      throw new IOException("Failed to open new chanel on sid: " + sid);
    }

    WebRtcDataStream channel = new WebRtcDataStream(sctpSocket, sid, label, false);

    channels.put(sid, channel);

    return channel;
  }
  /**
   * Handles control packet.
   *
   * @param data raw packet data that arrived on control PPID.
   * @param sid SCTP stream id on which the data has arrived.
   */
  private synchronized void onCtrlPacket(byte[] data, int sid) throws IOException {
    ByteBuffer buffer = ByteBuffer.wrap(data);
    int messageType = /* 1 byte unsigned integer */ 0xFF & buffer.get();

    if (messageType == MSG_CHANNEL_ACK) {
      if (logger.isDebugEnabled()) {
        logger.debug(getEndpoint().getID() + " ACK received SID: " + sid);
      }
      // Open channel ACK
      WebRtcDataStream channel = channels.get(sid);
      if (channel != null) {
        // Ack check prevents from firing multiple notifications
        // if we get more than one ACKs (by mistake/bug).
        if (!channel.isAcknowledged()) {
          channel.ackReceived();
          notifyChannelOpened(channel);
        } else {
          logger.warn("Redundant ACK received for SID: " + sid);
        }
      } else {
        logger.error("No channel exists on sid: " + sid);
      }
    } else if (messageType == MSG_OPEN_CHANNEL) {
      int channelType = /* 1 byte unsigned integer */ 0xFF & buffer.get();
      int priority = /* 2 bytes unsigned integer */ 0xFFFF & buffer.getShort();
      long reliability = /* 4 bytes unsigned integer */ 0xFFFFFFFFL & buffer.getInt();
      int labelLength = /* 2 bytes unsigned integer */ 0xFFFF & buffer.getShort();
      int protocolLength = /* 2 bytes unsigned integer */ 0xFFFF & buffer.getShort();
      String label;
      String protocol;

      if (labelLength == 0) {
        label = "";
      } else {
        byte[] labelBytes = new byte[labelLength];

        buffer.get(labelBytes);
        label = new String(labelBytes, "UTF-8");
      }
      if (protocolLength == 0) {
        protocol = "";
      } else {
        byte[] protocolBytes = new byte[protocolLength];

        buffer.get(protocolBytes);
        protocol = new String(protocolBytes, "UTF-8");
      }

      if (logger.isDebugEnabled()) {
        logger.debug(
            "!!! "
                + getEndpoint().getID()
                + " data channel open request on SID: "
                + sid
                + " type: "
                + channelType
                + " prio: "
                + priority
                + " reliab: "
                + reliability
                + " label: "
                + label
                + " proto: "
                + protocol);
      }

      if (channels.containsKey(sid)) {
        logger.error("Channel on sid: " + sid + " already exists");
      }

      WebRtcDataStream newChannel = new WebRtcDataStream(sctpSocket, sid, label, true);
      channels.put(sid, newChannel);

      sendOpenChannelAck(sid);

      notifyChannelOpened(newChannel);
    } else {
      logger.error("Unexpected ctrl msg type: " + messageType);
    }
  }
    /**
     * Inspect an <tt>RTCPCompoundPacket</tt> and build-up the state for future estimations.
     *
     * @param pkt
     */
    public void apply(RTCPCompoundPacket pkt) {
      if (pkt == null || pkt.packets == null || pkt.packets.length == 0) {
        return;
      }

      for (RTCPPacket rtcpPacket : pkt.packets) {
        switch (rtcpPacket.type) {
          case RTCPPacket.SR:
            RTCPSRPacket srPacket = (RTCPSRPacket) rtcpPacket;

            // The media sender SSRC.
            int ssrc = srPacket.ssrc;

            // Convert 64-bit NTP timestamp to Java standard time.
            // Note that java time (milliseconds) by definition has
            // less precision then NTP time (picoseconds) so
            // converting NTP timestamp to java time and back to NTP
            // timestamp loses precision. For example, Tue, Dec 17
            // 2002 09:07:24.810 EST is represented by a single
            // Java-based time value of f22cd1fc8a, but its NTP
            // equivalent are all values ranging from
            // c1a9ae1c.cf5c28f5 to c1a9ae1c.cf9db22c.

            // Use round-off on fractional part to preserve going to
            // lower precision
            long fraction = Math.round(1000D * srPacket.ntptimestamplsw / 0x100000000L);
            /*
             * If the most significant bit (MSB) on the seconds
             * field is set we use a different time base. The
             * following text is a quote from RFC-2030 (SNTP v4):
             *
             * If bit 0 is set, the UTC time is in the range
             * 1968-2036 and UTC time is reckoned from 0h 0m 0s UTC
             * on 1 January 1900. If bit 0 is not set, the time is
             * in the range 2036-2104 and UTC time is reckoned from
             * 6h 28m 16s UTC on 7 February 2036.
             */
            long msb = srPacket.ntptimestampmsw & 0x80000000L;
            long remoteTime =
                (msb == 0)
                    // use base: 7-Feb-2036 @ 06:28:16 UTC
                    ? msb0baseTime + (srPacket.ntptimestampmsw * 1000) + fraction
                    // use base: 1-Jan-1900 @ 01:00:00 UTC
                    : msb1baseTime + (srPacket.ntptimestampmsw * 1000) + fraction;

            // Estimate the clock rate of the sender.
            int frequencyHz = -1;
            if (receivedClocks.containsKey(ssrc)) {
              // Calculate the clock rate.
              ReceivedRemoteClock oldStats = receivedClocks.get(ssrc);
              RemoteClock oldRemoteClock = oldStats.getRemoteClock();
              frequencyHz =
                  Math.round(
                      (float)
                              (((int) srPacket.rtptimestamp - oldRemoteClock.getRtpTimestamp())
                                  & 0xffffffffl)
                          / (remoteTime - oldRemoteClock.getRemoteTime()));
            }

            // Replace whatever was in there before.
            receivedClocks.put(
                ssrc,
                new ReceivedRemoteClock(
                    ssrc, remoteTime, (int) srPacket.rtptimestamp, frequencyHz));
            break;
          case RTCPPacket.SDES:
            break;
        }
      }
    }