Always send RED headers if configured.

webrtc/video/video_send_stream.cc

 /*
  *  Copyright (c) 2013 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 641 matching lines @@
       RTC_DCHECK(ok);
     }
   }
 
   return return_value;
 }
 
 void VideoSendStream::ConfigureProtection() {
   // Enable NACK, FEC or both.
   const bool enable_protection_nack = config_.rtp.nack.rtp_history_ms > 0;
-  bool enable_protection_fec = config_.rtp.fec.red_payload_type != -1;
+  bool enable_protection_fec = config_.rtp.fec.ulpfec_payload_type != -1;
   // Payload types without picture ID cannot determine that a stream is complete
   // without retransmitting FEC, so using FEC + NACK for H.264 (for instance) is
   // a waste of bandwidth since FEC packets still have to be transmitted. Note
   // that this is not the case with FLEXFEC.
   if (enable_protection_nack &&
       !PayloadTypeSupportsSkippingFecPackets(
           config_.encoder_settings.payload_name)) {
     LOG(LS_WARNING) << "Transmitting payload type without picture ID using"
                        "NACK+FEC is a waste of bandwidth since FEC packets "
                        "also have to be retransmitted. Disabling FEC.";
     enable_protection_fec = false;
   }
 
   // Set to valid uint8_ts to be castable later without signed overflows.
   uint8_t payload_type_red = 0;
   uint8_t payload_type_fec = 0;
+
   // TODO(changbin): Should set RTX for RED mapping in RTP sender in future.
   // Validate payload types. If either RED or FEC payload types are set then
   // both should be. If FEC is enabled then they both have to be set.
-  if (enable_protection_fec || config_.rtp.fec.red_payload_type != -1 ||
-      config_.rtp.fec.ulpfec_payload_type != -1) {
+  if (config_.rtp.fec.red_payload_type != -1) {
     RTC_DCHECK_GE(config_.rtp.fec.red_payload_type, 0);

[mflodman, 2016/06/03 07:28:16]

Or change this to not allow 0.

[stefan-webrtc, 2016/06/03 07:50:18]

Will do! https://codereview.webrtc.org/2036083002

+    RTC_DCHECK_LE(config_.rtp.fec.red_payload_type, 127);
+    // TODO(holmer): We should only enable red if ulpfec is also enabled, but
+    // but due to an incompatibility issue with previous versions the receiver
+    // assumes rtx packets are containing red if it has been configured to
+    // receive red. Remove this in a few versions once the incompatibility
+    // issue is resolved (M53 timeframe).
+    payload_type_red = static_cast<uint8_t>(config_.rtp.fec.red_payload_type);
+  }
+  if (config_.rtp.fec.ulpfec_payload_type != -1) {
     RTC_DCHECK_GE(config_.rtp.fec.ulpfec_payload_type, 0);

[mflodman, 2016/06/03 07:28:16]

And here.

-    RTC_DCHECK_LE(config_.rtp.fec.red_payload_type, 127);
     RTC_DCHECK_LE(config_.rtp.fec.ulpfec_payload_type, 127);
-    payload_type_red = static_cast<uint8_t>(config_.rtp.fec.red_payload_type);
     payload_type_fec =
         static_cast<uint8_t>(config_.rtp.fec.ulpfec_payload_type);
-  } else {
-    // Payload types unset.
-    RTC_DCHECK_EQ(config_.rtp.fec.red_payload_type, -1);
-    RTC_DCHECK_EQ(config_.rtp.fec.ulpfec_payload_type, -1);
   }
 
   for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
     // Set NACK.
     rtp_rtcp->SetStorePacketsStatus(
         enable_protection_nack || congestion_controller_->pacer(),
         kMinSendSidePacketHistorySize);
     // Set FEC.
     for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
       rtp_rtcp->SetGenericFECStatus(enable_protection_fec, payload_type_red,
@@ skipping 101 matching lines @@
                           &module_nack_rate);
     *sent_video_rate_bps += module_video_rate;
     *sent_nack_rate_bps += module_nack_rate;
     *sent_fec_rate_bps += module_fec_rate;
   }
   return 0;
 }
 
 }  // namespace internal
 }  // namespace webrtc