Use RtcpPacket to send SLI in RtcpSender

webrtc/modules/rtp_rtcp/source/rtcp_sender.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 594 matching lines @@
 }
 
 /*
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |            First        |        Number           | PictureID |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */
 RTCPSender::BuildResult RTCPSender::BuildSLI(RtcpContext* ctx) {
-  // sanity
-  if (ctx->position + 16 >= IP_PACKET_SIZE)
+  rtcp::Sli sli;
+  sli.From(ssrc_);
+  sli.To(remote_ssrc_);
+  // Crop picture id to 6 least significant bits.
+  sli.WithPictureId(ctx->picture_id & 0x3F);
+  sli.WithFirstMb(0);
+  sli.WithNumberOfMb(0x1FFF);  // 13 bits, only ones for now.
+
+  PacketBuiltCallback callback(ctx);
+  if (!callback.BuildPacket(sli))
     return BuildResult::kTruncated;
 
-  // add slice loss indicator
-  uint8_t FMT = 2;
-  *ctx->AllocateData(1) = 0x80 + FMT;
-  *ctx->AllocateData(1) = 206;
-
-  // Used fixed length of 3
-  *ctx->AllocateData(1) = 0;
-  *ctx->AllocateData(1) = 3;
-
-  // Add our own SSRC
-  ByteWriter<uint32_t>::WriteBigEndian(ctx->AllocateData(4), ssrc_);
-
-  // Add the remote SSRC
-  ByteWriter<uint32_t>::WriteBigEndian(ctx->AllocateData(4), remote_ssrc_);
-
-  // Add first, number & picture ID 6 bits
-  // first  = 0, 13 - bits
-  // number = 0x1fff, 13 - bits only ones for now
-  uint32_t sliField = (0x1fff << 6) + (0x3f & ctx->picture_id);
-  ByteWriter<uint32_t>::WriteBigEndian(ctx->AllocateData(4), sliField);
-
   return BuildResult::kSuccess;
 }
 
 /*
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |      PB       |0| Payload Type|    Native RPSI bit string     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   defined per codec          ...                | Padding (0) |
@@ skipping 838 matching lines @@
 
 bool RTCPSender::AllVolatileFlagsConsumed() const {
   for (const ReportFlag& flag : report_flags_) {
     if (flag.is_volatile)
       return false;
   }
   return true;
 }
 
 }  // namespace webrtc