Remove hardcoded kValueSizeBytes values from variable-length header extensions.

webrtc/modules/rtp_rtcp/source/rtp_sender_video.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 15 matching lines @@
 #include "webrtc/modules/rtp_rtcp/source/rtp_format_vp8.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_format_vp9.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_packet_to_send.h"
 
 namespace webrtc {
 
 namespace {
 constexpr size_t kRedForFecHeaderLength = 1;
 
+constexpr RTPExtensionSizeInfo kFecExtensionSizes[] = {

[danilchap, 2017/05/08 16:25:06]

how this list is different from kExtensionSizes in rtp_sender.cc ?

may be add an accessor to RTPSender:
static rtc::ArrayView<> ???ExtensionSizes();

[erikvarga1, 2017/05/09 11:40:03]

Done, I've added a getter for the FEC packets.

Also, since RtpHeaderLength() might be used for other packets later on, I
figured it'd make sense for it to have an |extension_sizes| arg instead of using
kExtensionSizes directly.

[danilchap, 2017/05/09 12:33:49]

Do you know such packets?
It is generally better to make code simpler now and add complexity only when you
about to use it.

[erikvarga1, 2017/05/09 13:30:30]

Alright, since it's not used elsewhere, I guess it makes more sense to have the
function work for the padding/fec packets only. I removed the extra arg and just
added a comment instead.

+    CreateExtensionSizeInfo<AbsoluteSendTime>(),
+    CreateExtensionSizeInfo<TransmissionOffset>(),
+    CreateExtensionSizeInfo<TransportSequenceNumber>(),
+    CreateExtensionSizeInfo<PlayoutDelayLimits>(),
+};
+
 void BuildRedPayload(const RtpPacketToSend& media_packet,
                      RtpPacketToSend* red_packet) {
   uint8_t* red_payload = red_packet->AllocatePayload(
       kRedForFecHeaderLength + media_packet.payload_size());
   RTC_DCHECK(red_payload);
   red_payload[0] = media_packet.PayloadType();
 
   auto media_payload = media_packet.payload();
   memcpy(&red_payload[kRedForFecHeaderLength], media_payload.data(),
          media_payload.size());
@@ skipping 196 matching lines @@
 
 void RTPSenderVideo::GetUlpfecConfig(int* red_payload_type,
                                      int* ulpfec_payload_type) const {
   rtc::CritScope cs(&crit_);
   *red_payload_type = red_payload_type_;
   *ulpfec_payload_type = ulpfec_payload_type_;
 }
 
 size_t RTPSenderVideo::CalculateFecPacketOverhead() const {
   if (flexfec_enabled())
-    return flexfec_sender_->MaxPacketOverhead();
+    return flexfec_sender_->MaxPacketOverhead(kFecExtensionSizes);
 
   size_t overhead = 0;
   if (red_enabled()) {
     // The RED overhead is due to a small header.
     overhead += kRedForFecHeaderLength;
   }
   if (ulpfec_enabled()) {
     // For ULPFEC, the overhead is the FEC headers plus RED for FEC header
     // (see above) plus anything in RTP header beyond the 12 bytes base header
     // (CSRC list, extensions...)
@@ skipping 160 matching lines @@
   rtc::CritScope cs(&crit_);
   return retransmission_settings_;
 }
 
 void RTPSenderVideo::SetSelectiveRetransmissions(uint8_t settings) {
   rtc::CritScope cs(&crit_);
   retransmission_settings_ = settings;
 }
 
 }  // namespace webrtc