From dd4edc5813a0331049f53a93ac2404a8899e6ae8 Mon Sep 17 00:00:00 2001
From: sprang <sprang@webrtc.org>
Date: Fri, 21 Aug 2015 04:21:51 -0700
Subject: [PATCH] Reland of Use RtcpPacket to send REMB in RtcpSender (patchset
 #1 id:1 of https://codereview.webrtc.org/1300863002/ )

Reason for revert:
This wasn't the cause of the breakage. Re-reverting.
https://code.google.com/p/webrtc/issues/detail?id=4923

Original issue's description:
> Revert of Use RtcpPacket to send REMB in RtcpSender (patchset #1 id:1 of https://codereview.webrtc.org/1290573004/ )
>
> Reason for revert:
> A few bots started failing rtc_unittests after this was commited. Ex https://build.chromium.org/p/client.webrtc/builders/Linux64%20Debug/builds/5048
>
> Original issue's description:
> > Use RtcpPacket to send REMB in RtcpSender
> >
> > BUG=webrtc:2450
> > R=asapersson@webrtc.org
> >
> > Committed: https://chromium.googlesource.com/external/webrtc/+/35ab4baa20a730de71b390008900a16563cbbe8e
>
> TBR=asapersson@webrtc.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:2450
>
> Committed: https://crrev.com/141c5951f4beda868797c2746002a4b1b267ab2a
> Cr-Commit-Position: refs/heads/master@{#9723}

TBR=asapersson@webrtc.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:2450

Review URL: https://codereview.webrtc.org/1309723002

Cr-Commit-Position: refs/heads/master@{#9754}
---
 webrtc/modules/rtp_rtcp/source/rtcp_sender.cc | 48 ++++---------------
 1 file changed, 8 insertions(+), 40 deletions(-)

diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc b/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc
index e118fb262c..5ebd4a895d 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_sender.cc
@@ -638,48 +638,16 @@ RTCPSender::BuildResult RTCPSender::BuildRPSI(RtcpContext* ctx) {
 }
 
 RTCPSender::BuildResult RTCPSender::BuildREMB(RtcpContext* ctx) {
-  // sanity
-  if (ctx->position + 20 + 4 * remb_ssrcs_.size() >= IP_PACKET_SIZE)
+  rtcp::Remb remb;
+  remb.From(ssrc_);
+  for (uint32_t ssrc : remb_ssrcs_)
+    remb.AppliesTo(ssrc);
+  remb.WithBitrateBps(remb_bitrate_);
+
+  PacketBuiltCallback callback(ctx);
+  if (!callback.BuildPacket(remb))
     return BuildResult::kTruncated;
 
-  // add application layer feedback
-  uint8_t FMT = 15;
-  *ctx->AllocateData(1) = 0x80 + FMT;
-  *ctx->AllocateData(1) = 206;
-
-  *ctx->AllocateData(1) = 0;
-  *ctx->AllocateData(1) = static_cast<uint8_t>(remb_ssrcs_.size() + 4);
-
-  // Add our own SSRC
-  ByteWriter<uint32_t>::WriteBigEndian(ctx->AllocateData(4), ssrc_);
-
-  // Remote SSRC must be 0
-  ByteWriter<uint32_t>::WriteBigEndian(ctx->AllocateData(4), 0);
-
-  *ctx->AllocateData(1) = 'R';
-  *ctx->AllocateData(1) = 'E';
-  *ctx->AllocateData(1) = 'M';
-  *ctx->AllocateData(1) = 'B';
-
-  *ctx->AllocateData(1) = remb_ssrcs_.size();
-  // 6 bit Exp
-  // 18 bit mantissa
-  uint8_t brExp = 0;
-  for (uint32_t i = 0; i < 64; i++) {
-    if (remb_bitrate_ <= (0x3FFFFu << i)) {
-      brExp = i;
-      break;
-    }
-  }
-  const uint32_t brMantissa = (remb_bitrate_ >> brExp);
-  *ctx->AllocateData(1) =
-      static_cast<uint8_t>((brExp << 2) + ((brMantissa >> 16) & 0x03));
-  *ctx->AllocateData(1) = static_cast<uint8_t>(brMantissa >> 8);
-  *ctx->AllocateData(1) = static_cast<uint8_t>(brMantissa);
-
-  for (size_t i = 0; i < remb_ssrcs_.size(); i++)
-    ByteWriter<uint32_t>::WriteBigEndian(ctx->AllocateData(4), remb_ssrcs_[i]);
-
   TRACE_EVENT_INSTANT0(TRACE_DISABLED_BY_DEFAULT("webrtc_rtp"),
                        "RTCPSender::REMB");