WebRTC判断是否是rtcp包

bool RtpHeaderParser::RTCP() const {
  // 72 to 76 is reserved for RTP
  // 77 to 79 is not reserver but  they are not assigned we will block them
  // for RTCP 200 SR  == marker bit + 72
  // for RTCP 204 APP == marker bit + 76
  /*
   *       RTCP
   *
   * FIR      full INTRA-frame request             192     [RFC2032]   supported
   * NACK     negative acknowledgement             193     [RFC2032]
   * IJ       Extended inter-arrival jitter report 195 [RFC-ietf-avt-rtp-toff
   * set-07.txt] http://tools.ietf.org/html/draft-ietf-avt-rtp-toffset-07
   * SR       sender report                        200     [RFC3551]   supported
   * RR       receiver report                      201     [RFC3551]   supported
   * SDES     source description                   202     [RFC3551]   supported
   * BYE      goodbye                              203     [RFC3551]   supported
   * APP      application-defined                  204     [RFC3551]   ignored
   * RTPFB    Transport layer FB message           205     [RFC4585]   supported
   * PSFB     Payload-specific FB message          206     [RFC4585]   supported
   * XR       extended report                      207     [RFC3611]   supported
   */

  /* 205       RFC 5104
   * FMT 1      NACK       supported
   * FMT 2      reserved
   * FMT 3      TMMBR      supported
   * FMT 4      TMMBN      supported
   */

  /* 206      RFC 5104
   * FMT 1:     Picture Loss Indication (PLI)                      supported
   * FMT 2:     Slice Lost Indication (SLI)
   * FMT 3:     Reference Picture Selection Indication (RPSI)
   * FMT 4:     Full Intra Request (FIR) Command                   supported
   * FMT 5:     Temporal-Spatial Trade-off Request (TSTR)
   * FMT 6:     Temporal-Spatial Trade-off Notification (TSTN)
   * FMT 7:     Video Back Channel Message (VBCM)
   * FMT 15:    Application layer FB message
   */

  const ptrdiff_t length = _ptrRTPDataEnd - _ptrRTPDataBegin;
  if (length < kRtcpMinHeaderLength) {
    return false;
  }

  const uint8_t V = _ptrRTPDataBegin[0] >> 6;
  if (V != kRtcpExpectedVersion) {
    return false;
  }

  const uint8_t payloadType = _ptrRTPDataBegin[1];
  switch (payloadType) {
    case 192:
      return true;
    case 193:
      // not supported
      // pass through and check for a potential RTP packet
      return false;
    case 195:
    case 200:
    case 201:
    case 202:
    case 203:
    case 204:
    case 205:
    case 206:
    case 207:
      return true;
    default:
      return false;
  }
}

来源：CSDN

作者：weixin_g632637774

链接：https://blog.csdn.net/glw0223/article/details/103628472