Wire up FlexfecSender in RTPSenderVideo.

webrtc/modules/rtp_rtcp/source/flexfec_sender.cc

Index: webrtc/modules/rtp_rtcp/source/flexfec_sender.cc
diff --git a/webrtc/modules/rtp_rtcp/source/flexfec_sender.cc b/webrtc/modules/rtp_rtcp/source/flexfec_sender.cc
index 55e8e5266919bbb978b44e8d5fcd1fff356549c1..54ed1ab089468c7c5df720452c5e4b56205cf0e6 100644
--- a/webrtc/modules/rtp_rtcp/source/flexfec_sender.cc
+++ b/webrtc/modules/rtp_rtcp/source/flexfec_sender.cc
@@ -38,6 +38,26 @@ const int kMsToRtpTimestamp = kVideoPayloadTypeFrequency / 1000;
 // How often to log the generated FEC packets to the text log.
 constexpr int64_t kPacketLogIntervalMs = 10000;
 
+// Only activate BWE header extensions for FlexFEC.
+RtpHeaderExtensionMap FilterRtpHeaderExtensions(
+    const std::vector<RtpExtension>& rtp_header_extensions) {
+  RtpHeaderExtensionMap map;
+  for (const auto& extension : rtp_header_extensions) {
+    if (extension.uri == RtpExtension::kTransportSequenceNumberUri) {
+      map.Register(kRtpExtensionTransportSequenceNumber, extension.id);

[danilchap, 2016/11/10 11:29:23]

I would like to remove this version of Register eventually,
can you write instead
if (extension.uri == TransportSequenceNumber::kUri) {
  map.Register<TransportSequenceNumber>(extension.id);
}
(template version also slightly faster, thought that is negligible)

[brandtr, 2016/11/10 12:00:41]

Done.

+    } else if (extension.uri == RtpExtension::kAbsSendTimeUri) {
+      map.Register(kRtpExtensionAbsoluteSendTime, extension.id);
+    } else if (extension.uri == RtpExtension::kTimestampOffsetUri) {
+      map.Register(kRtpExtensionTransmissionTimeOffset, extension.id);
+    } else {
+      LOG(LS_WARNING) << "RTP header extension with id: " << extension.id
+                      << ", uri: " << extension.uri
+                      << ", is unsupported by FlexfecSender.";
+    }
+  }
+  return map;
+}
+
 }  // namespace
 
 FlexfecSender::FlexfecSender(
@@ -57,7 +77,8 @@ FlexfecSender::FlexfecSender(
       protected_media_ssrc_(protected_media_ssrc),
       seq_num_(random_.Rand(1, kMaxInitRtpSeqNumber)),
       ulpfec_generator_(ForwardErrorCorrection::CreateFlexfec()),
-      rtp_header_extension_map_() {
+      rtp_header_extension_map_(
+          FilterRtpHeaderExtensions(rtp_header_extensions)) {

[danilchap, 2016/11/10 11:29:23]

maybe  call this function 'RegisterBweExtensions'
so that it would fit on one line.

[brandtr, 2016/11/10 12:00:41]

Done.

   // This object should not have been instantiated if FlexFEC is disabled.
   RTC_DCHECK_GE(payload_type, 0);
   RTC_DCHECK_LE(payload_type, 127);
@@ -65,24 +86,6 @@ FlexfecSender::FlexfecSender(
   // It's OK to create this object on a different thread/task queue than
   // the one used during main operation.
   sequence_checker_.Detach();
-
-  // Register RTP header extensions for BWE.
-  for (const auto& extension : rtp_header_extensions) {
-    if (extension.uri == RtpExtension::kTransportSequenceNumberUri) {
-      rtp_header_extension_map_.Register(kRtpExtensionTransportSequenceNumber,
-                                         extension.id);
-    } else if (extension.uri == RtpExtension::kAbsSendTimeUri) {
-      rtp_header_extension_map_.Register(kRtpExtensionAbsoluteSendTime,
-                                         extension.id);
-    } else if (extension.uri == RtpExtension::kTimestampOffsetUri) {
-      rtp_header_extension_map_.Register(kRtpExtensionTransmissionTimeOffset,
-                                         extension.id);
-    } else {
-      LOG(LS_WARNING) << "RTP header extension with id: " << extension.id
-                      << ", uri: " << extension.uri
-                      << ", is unsupported by FlexfecSender.";
-    }
-  }
 }
 
 FlexfecSender::~FlexfecSender() = default;
@@ -158,8 +161,10 @@ FlexfecSender::GetFecPackets() {
   return fec_packets_to_send;
 }
 
+// For FlexFEC, the overhead is the FEC header, as well as the BWE header exts.

[danilchap, 2016/11/10 11:29:23]

may be instead of shortering word remove redundant words:
// The overhead is BWE rtp header extensions and FlexFEC header.

[brandtr, 2016/11/10 12:00:41]

Done.

 size_t FlexfecSender::MaxPacketOverhead() const {
-  return kFlexfecMaxHeaderSize;
+  return kFlexfecMaxHeaderSize +
+         rtp_header_extension_map_.GetTotalLengthInBytes();

[danilchap, 2016/11/10 11:29:23]

really tiny nit: may be sum other way around since in a raw packet extensions go
before flexfec header.

[brandtr, 2016/11/10 12:00:41]

I like that! These things make the code easier to interpret, IMO. Thanks for the
comment.

 }
 
 }  // namespace webrtc