Add FlexfecSender.

webrtc/modules/rtp_rtcp/source/flexfec_sender_impl.h

Index: webrtc/modules/rtp_rtcp/source/flexfec_sender_impl.h
diff --git a/webrtc/modules/rtp_rtcp/source/flexfec_sender_impl.h b/webrtc/modules/rtp_rtcp/source/flexfec_sender_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..09e6de03970eddae8bcba402b9c4956f37da91b3
--- /dev/null
+++ b/webrtc/modules/rtp_rtcp/source/flexfec_sender_impl.h
@@ -0,0 +1,64 @@
+/*
+ *  Copyright (c) 2016 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.
+ */
+
+#ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_FLEXFEC_SENDER_IMPL_H_
+#define WEBRTC_MODULES_RTP_RTCP_SOURCE_FLEXFEC_SENDER_IMPL_H_
+
+#include <memory>
+#include <vector>
+
+#include "webrtc/base/basictypes.h"
+#include "webrtc/base/random.h"
+#include "webrtc/base/sequenced_task_checker.h"
+#include "webrtc/modules/rtp_rtcp/include/flexfec_sender.h"
+#include "webrtc/modules/rtp_rtcp/source/producer_fec.h"
+#include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
+#include "webrtc/system_wrappers/include/clock.h"
+
+namespace webrtc {
+
+class FlexfecSenderImpl : public FlexfecSender {

[stefan-webrtc, 2016/11/02 13:02:42]

I'm thinking that maybe we should skip having an interface, and just expose the
impl. If we ever want to have two implementations we could add the interface
later, WDYT?

[brandtr, 2016/11/02 14:04:37]

I think having the interface is cumbersome, and if we can avoid it that would be
nice. The reason for having it is that this class will be owned by objects
outside the rtp_rtcp module, however. With the current design, the FlexfecSender
will be owned by VideoSendStream(*). With the future design, the FlexfecSender
will be owned by either Call or PacedSender.

(*) The FlexfecSender could also conceivably be owned by the RTP module, but
let's discuss the benefits/drawbacks of that setup offline.

+ public:
+  FlexfecSenderImpl(int flexfec_payload_type,
+                    uint32_t flexfec_ssrc,
+                    uint32_t protected_media_ssrc,
+                    const std::vector<RtpExtension>& rtp_header_extensions,
+                    Clock* clock);
+  ~FlexfecSenderImpl();
+
+  // Implements FlexfecSender.
+  void SetFecParameters(const FecProtectionParams& params) override;
+  int AddRtpPacketAndGenerateFec(const RtpPacketToSend& packet) override;
+  bool FecAvailable() const override;
+  std::vector<std::unique_ptr<RtpPacketToSend>> GetFecPackets() override;
+  size_t MaxPacketOverhead() const override;
+
+ private:
+  // Utility.
+  Clock* const clock_;
+  Random random_;
+  int64_t last_generated_packet_ms_;
+  rtc::SequencedTaskChecker sequence_checker_;
+
+  // Config.
+  const int flexfec_payload_type_;
+  uint16_t seq_num_;
+  const uint32_t timestamp_offset_;
+  const uint32_t flexfec_ssrc_;
+  const uint32_t protected_media_ssrc_;
+
+  // Implementation.
+  ProducerFec ulpfec_sender_;
+  RtpHeaderExtensionMap rtp_header_extension_map_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_FLEXFEC_SENDER_IMPL_H_