/**
   * Makes an <tt>RTCPREMBPacket</tt> that provides receiver feedback to the endpoint from which we
   * receive.
   *
   * @return an <tt>RTCPREMBPacket</tt> that provides receiver feedback to the endpoint from which
   *     we receive.
   */
  private RTCPREMBPacket makeRTCPREMBPacket() {
    // TODO we should only make REMBs if REMB support has been advertised.
    // Destination
    RemoteBitrateEstimator remoteBitrateEstimator =
        ((VideoMediaStream) getStream()).getRemoteBitrateEstimator();

    Collection<Integer> ssrcs = remoteBitrateEstimator.getSsrcs();

    // TODO(gp) intersect with SSRCs from signaled simulcast layers
    // NOTE(gp) The Google Congestion Control algorithm (sender side)
    // doesn't seem to care about the SSRCs in the dest field.
    long[] dest = new long[ssrcs.size()];
    int i = 0;

    for (Integer ssrc : ssrcs) dest[i++] = ssrc & 0xFFFFFFFFL;

    // Exp & mantissa
    long bitrate = remoteBitrateEstimator.getLatestEstimate();

    if (bitrate == -1) return null;

    if (logger.isDebugEnabled()) logger.debug("Estimated bitrate: " + bitrate);

    // Create and return the packet.
    // We use the stream's local source ID (SSRC) as the SSRC of packet
    // sender.
    long streamSSRC = getLocalSSRC();

    return new RTCPREMBPacket(streamSSRC, /* mediaSSRC */ 0L, bitrate, dest);
  }
  /**
   * Makes <tt>RTCPSDES</tt> packets for all the RTP streams that we're sending.
   *
   * @return a <tt>List</tt> of <tt>RTCPSDES</tt> packets for all the RTP streams that we're
   *     sending.
   */
  private RTCPSDESPacket makeSDESPacket() {
    Collection<RTCPSDES> sdesChunks = new ArrayList<RTCPSDES>();

    // Create an SDES for our own SSRC.
    RTCPSDES ownSDES = new RTCPSDES();

    SSRCInfo ourinfo = getStream().getStreamRTPManager().getSSRCCache().ourssrc;
    ownSDES.ssrc = (int) getLocalSSRC();
    Collection<RTCPSDESItem> ownItems = new ArrayList<RTCPSDESItem>();
    ownItems.add(new RTCPSDESItem(RTCPSDESItem.CNAME, ourinfo.sourceInfo.getCNAME()));

    // Throttle the source description bandwidth. See RFC3550#6.3.9
    // Allocation of Source Description Bandwidth.

    if (sdesCounter % 3 == 0) {
      if (ourinfo.name != null && ourinfo.name.getDescription() != null)
        ownItems.add(new RTCPSDESItem(RTCPSDESItem.NAME, ourinfo.name.getDescription()));
      if (ourinfo.email != null && ourinfo.email.getDescription() != null)
        ownItems.add(new RTCPSDESItem(RTCPSDESItem.EMAIL, ourinfo.email.getDescription()));
      if (ourinfo.phone != null && ourinfo.phone.getDescription() != null)
        ownItems.add(new RTCPSDESItem(RTCPSDESItem.PHONE, ourinfo.phone.getDescription()));
      if (ourinfo.loc != null && ourinfo.loc.getDescription() != null)
        ownItems.add(new RTCPSDESItem(RTCPSDESItem.LOC, ourinfo.loc.getDescription()));
      if (ourinfo.tool != null && ourinfo.tool.getDescription() != null)
        ownItems.add(new RTCPSDESItem(RTCPSDESItem.TOOL, ourinfo.tool.getDescription()));
      if (ourinfo.note != null && ourinfo.note.getDescription() != null)
        ownItems.add(new RTCPSDESItem(RTCPSDESItem.NOTE, ourinfo.note.getDescription()));
    }

    sdesCounter++;

    ownSDES.items = ownItems.toArray(new RTCPSDESItem[ownItems.size()]);

    sdesChunks.add(ownSDES);

    for (Map.Entry<Integer, byte[]> entry : cnameRegistry.entrySet()) {
      RTCPSDES sdes = new RTCPSDES();
      sdes.ssrc = entry.getKey();
      sdes.items = new RTCPSDESItem[] {new RTCPSDESItem(RTCPSDESItem.CNAME, entry.getValue())};
    }

    RTCPSDES[] sps = sdesChunks.toArray(new RTCPSDES[sdesChunks.size()]);
    RTCPSDESPacket sp = new RTCPSDESPacket(sps);

    return sp;
  }
    /**
     * Removes receiver and sender feedback from RTCP packets.
     *
     * @param inPacket the <tt>RTCPCompoundPacket</tt> to filter.
     * @return the filtered <tt>RawPacket</tt>.
     */
    public RawPacket gateway(RTCPCompoundPacket inPacket) {
      if (inPacket == null || inPacket.packets == null || inPacket.packets.length == 0) {
        logger.info("Ignoring empty RTCP packet.");
        return null;
      }

      ArrayList<RTCPPacket> outPackets = new ArrayList<RTCPPacket>(inPacket.packets.length);

      for (RTCPPacket p : inPacket.packets) {
        switch (p.type) {
          case RTCPPacket.RR:
          case RTCPPacket.SR:
          case RTCPPacket.SDES:
            // We generate our own RR/SR/SDES packets. We only want
            // to forward NACKs/PLIs/etc.
            break;
          case RTCPFBPacket.PSFB:
            RTCPFBPacket psfb = (RTCPFBPacket) p;
            switch (psfb.fmt) {
              case RTCPREMBPacket.FMT:
                // We generate its own REMB packets.
                break;
              default:
                // We let through everything else, like NACK
                // packets.
                outPackets.add(psfb);
                break;
            }
            break;
          default:
            // We let through everything else, like BYE and APP
            // packets.
            outPackets.add(p);
            break;
        }
      }

      if (outPackets.size() == 0) {
        return null;
      }

      // We have feedback messages to send. Pack them in a compound
      // RR and send them. TODO Use RFC5506 Reduced-Size RTCP, if the
      // receiver supports it.
      Collection<RTCPRRPacket> rrPackets = makeRTCPRRPackets(System.currentTimeMillis());

      if (rrPackets != null && rrPackets.size() != 0) {
        outPackets.addAll(0, rrPackets);
      } else {
        logger.warn("We might be sending invalid RTCPs.");
      }

      RTCPPacket[] pkts = outPackets.toArray(new RTCPPacket[outPackets.size()]);
      RTCPCompoundPacket outPacket = new RTCPCompoundPacket(pkts);

      return generator.apply(outPacket);
    }
  /**
   * Iterate through all the <tt>ReceiveStream</tt>s that this <tt>MediaStream</tt> has and make
   * <tt>RTCPReportBlock</tt>s for all of them.
   *
   * @param time
   * @return
   */
  private RTCPReportBlock[] makeRTCPReportBlocks(long time) {
    MediaStream stream = getStream();
    // State validation.
    if (stream == null) {
      logger.warn("stream is null.");
      return MIN_RTCP_REPORTS_BLOCKS_ARRAY;
    }

    StreamRTPManager streamRTPManager = stream.getStreamRTPManager();
    if (streamRTPManager == null) {
      logger.warn("streamRTPManager is null.");
      return MIN_RTCP_REPORTS_BLOCKS_ARRAY;
    }

    Collection<ReceiveStream> receiveStreams = streamRTPManager.getReceiveStreams();

    if (receiveStreams == null || receiveStreams.size() == 0) {
      logger.info("There are no receive streams to build report " + "blocks for.");
      return MIN_RTCP_REPORTS_BLOCKS_ARRAY;
    }

    SSRCCache cache = streamRTPManager.getSSRCCache();
    if (cache == null) {
      logger.info("cache is null.");
      return MIN_RTCP_REPORTS_BLOCKS_ARRAY;
    }

    // Create the return object.
    Collection<RTCPReportBlock> rtcpReportBlocks = new ArrayList<RTCPReportBlock>();

    // Populate the return object.
    for (ReceiveStream receiveStream : receiveStreams) {
      // Dig into the guts of FMJ and get the stats for the current
      // receiveStream.
      SSRCInfo info = cache.cache.get((int) receiveStream.getSSRC());

      if (!info.ours && info.sender) {
        RTCPReportBlock rtcpReportBlock = info.makeReceiverReport(time);
        rtcpReportBlocks.add(rtcpReportBlock);
      }
    }

    return rtcpReportBlocks.toArray(new RTCPReportBlock[rtcpReportBlocks.size()]);
  }
  /** {@inheritDoc} */
  @Override
  public RawPacket report() {
    garbageCollector.cleanup();

    // TODO Compound RTCP packets should not exceed the MTU of the network
    // path.
    //
    // An individual RTP participant should send only one compound RTCP
    // packet per report interval in order for the RTCP bandwidth per
    // participant to be estimated correctly, except when the compound
    // RTCP packet is split for partial encryption.
    //
    // If there are too many sources to fit all the necessary RR packets
    // into one compound RTCP packet without exceeding the maximum
    // transmission unit (MTU) of the network path, then only the subset
    // that will fit into one MTU should be included in each interval. The
    // subsets should be selected round-robin across multiple intervals so
    // that all sources are reported.
    //
    // It is impossible to know in advance what the MTU of path will be.
    // There are various algorithms for experimenting to find out, but many
    // devices do not properly implement (or deliberately ignore) the
    // necessary standards so it all comes down to trial and error. For that
    // reason, we can just guess 1200 or 1500 bytes per message.
    long time = System.currentTimeMillis();

    Collection<RTCPPacket> packets = new ArrayList<RTCPPacket>();

    // First, we build the RRs.
    Collection<RTCPRRPacket> rrPackets = makeRTCPRRPackets(time);
    if (rrPackets != null && rrPackets.size() != 0) {
      packets.addAll(rrPackets);
    }

    // Next, we build the SRs.
    Collection<RTCPSRPacket> srPackets = makeRTCPSRPackets(time);
    if (srPackets != null && srPackets.size() != 0) {
      packets.addAll(srPackets);
    }

    // Bail out if we have nothing to report.
    if (packets.size() == 0) {
      return null;
    }

    // Next, we build the REMB.
    RTCPREMBPacket rembPacket = makeRTCPREMBPacket();
    if (rembPacket != null) {
      packets.add(rembPacket);
    }

    // Finally, we add an SDES packet.
    RTCPSDESPacket sdesPacket = makeSDESPacket();
    if (sdesPacket != null) {
      packets.add(sdesPacket);
    }

    // Prepare the <tt>RTCPCompoundPacket</tt> to return.
    RTCPPacket rtcpPackets[] = packets.toArray(new RTCPPacket[packets.size()]);

    RTCPCompoundPacket cp = new RTCPCompoundPacket(rtcpPackets);

    // Build the <tt>RTCPCompoundPacket</tt> and return the
    // <tt>RawPacket</tt> to inject to the <tt>MediaStream</tt>.
    return generator.apply(cp);
  }