Generalize FEC header formatting. (pt. 4)

webrtc/modules/rtp_rtcp/source/producer_fec.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.
  */
 
 #include "webrtc/modules/rtp_rtcp/source/producer_fec.h"
 
 #include <memory>
 #include <utility>
 
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
 #include "webrtc/modules/rtp_rtcp/source/forward_error_correction.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_utility.h"
 
 namespace webrtc {
 
 constexpr size_t kRedForFecHeaderLength = 1;
 
 // This controls the maximum amount of excess overhead (actual - target)
-// allowed in order to trigger GenerateFec(), before |params_.max_fec_frames|
+// allowed in order to trigger EncodeFec(), before |params_.max_fec_frames|
 // is reached. Overhead here is defined as relative to number of media packets.
 constexpr int kMaxExcessOverhead = 50;  // Q8.
 
 // This is the minimum number of media packets required (above some protection
-// level) in order to trigger GenerateFec(), before |params_.max_fec_frames| is
+// level) in order to trigger EncodeFec(), before |params_.max_fec_frames| is
 // reached.
 constexpr size_t kMinMediaPackets = 4;
 
 // Threshold on the received FEC protection level, above which we enforce at
 // least |kMinMediaPackets| packets for the FEC code. Below this
 // threshold |kMinMediaPackets| is set to default value of 1.
 //
 // The range is between 0 and 255, where 255 corresponds to 100% overhead
 // (relative to the number of protected media packets).
 constexpr uint8_t kHighProtectionThreshold = 80;
@@ skipping 42 matching lines @@
 }
 
 uint8_t* RedPacket::data() const {
   return data_.get();
 }
 
 size_t RedPacket::length() const {
   return length_;
 }
 
-ProducerFec::ProducerFec(ForwardErrorCorrection* fec)
-    : fec_(fec),
+ProducerFec::ProducerFec()
+    : fec_(ForwardErrorCorrection::CreateUlpfec()),
       media_packets_(),
       generated_fec_packets_(),
       num_protected_frames_(0),
       num_important_packets_(0),
       min_num_media_packets_(1),
       params_(),
       new_params_() {
   memset(&params_, 0, sizeof(params_));
   memset(&new_params_, 0, sizeof(new_params_));
 }
@@ skipping 15 matching lines @@
   red_packet->AssignPayload(data_buffer + rtp_header_length, payload_length);
   return red_packet;
 }
 
 void ProducerFec::SetFecParameters(const FecProtectionParams* params,
                                    int num_important_packets) {
   // Number of important packets (i.e. number of packets receiving additional
   // protection in 'unequal protection mode') cannot exceed kMaxMediaPackets.
   RTC_DCHECK_GE(params->fec_rate, 0);
   RTC_DCHECK_LE(params->fec_rate, 255);
-  if (num_important_packets >
-      static_cast<int>(ForwardErrorCorrection::kMaxMediaPackets)) {
-    num_important_packets = ForwardErrorCorrection::kMaxMediaPackets;
+  if (num_important_packets > static_cast<int>(kUlpfecMaxMediaPackets)) {
+    num_important_packets = kUlpfecMaxMediaPackets;
   }
   // Store the new params and apply them for the next set of FEC packets being
   // produced.
   new_params_ = *params;
   num_important_packets_ = num_important_packets;
   if (params->fec_rate > kHighProtectionThreshold) {
     min_num_media_packets_ = kMinMediaPackets;
   } else {
     min_num_media_packets_ = 1;
   }
 }
 
 int ProducerFec::AddRtpPacketAndGenerateFec(const uint8_t* data_buffer,
                                             size_t payload_length,
                                             size_t rtp_header_length) {
   RTC_DCHECK(generated_fec_packets_.empty());
   if (media_packets_.empty()) {
     params_ = new_params_;
   }
   bool complete_frame = false;
   const bool marker_bit = (data_buffer[1] & kRtpMarkerBitMask) ? true : false;
-  if (media_packets_.size() < ForwardErrorCorrection::kMaxMediaPackets) {
-    // Generic FEC can only protect up to |kMaxMediaPackets| packets.
+  if (media_packets_.size() < kUlpfecMaxMediaPackets) {
+    // Generic FEC can only protect up to kMaxMediaPackets packets.
     std::unique_ptr<ForwardErrorCorrection::Packet> packet(
         new ForwardErrorCorrection::Packet());
     packet->length = payload_length + rtp_header_length;
     memcpy(packet->data, data_buffer, packet->length);
     media_packets_.push_back(std::move(packet));
   }
   if (marker_bit) {
     ++num_protected_frames_;
     complete_frame = true;
   }
   // Produce FEC over at most |params_.max_fec_frames| frames, or as soon as:
   // (1) the excess overhead (actual overhead - requested/target overhead) is
   // less than |kMaxExcessOverhead|, and
   // (2) at least |min_num_media_packets_| media packets is reached.
   if (complete_frame &&
       (num_protected_frames_ == params_.max_fec_frames ||
        (ExcessOverheadBelowMax() && MinimumMediaPacketsReached()))) {
     RTC_DCHECK_LE(num_important_packets_,
-                  static_cast<int>(ForwardErrorCorrection::kMaxMediaPackets));
+                  static_cast<int>(kUlpfecMaxMediaPackets));
     // TODO(pbos): Consider whether unequal protection should be enabled or not,
     // it is currently always disabled.
     //
     // Since unequal protection is disabled, the value of
     // |num_important_packets_| has no importance when calling GenerateFec().
     constexpr bool kUseUnequalProtection = false;
-    int ret = fec_->GenerateFec(media_packets_, params_.fec_rate,
-                                num_important_packets_, kUseUnequalProtection,
-                                params_.fec_mask_type, &generated_fec_packets_);
+    int ret = fec_.EncodeFec(media_packets_, params_.fec_rate,
+                             num_important_packets_, kUseUnequalProtection,
+                             params_.fec_mask_type, &generated_fec_packets_);
     if (generated_fec_packets_.empty()) {
       num_protected_frames_ = 0;
       DeleteMediaPackets();
     }
     return ret;
   }
   return 0;
 }
 
 bool ProducerFec::ExcessOverheadBelowMax() const {
@@ skipping 14 matching lines @@
 }
 
 bool ProducerFec::FecAvailable() const {
   return !generated_fec_packets_.empty();
 }
 
 size_t ProducerFec::NumAvailableFecPackets() const {
   return generated_fec_packets_.size();
 }
 
+size_t ProducerFec::MaxPacketOverhead() const {
+  return fec_.MaxPacketOverhead();
+}
+
 std::vector<std::unique_ptr<RedPacket>> ProducerFec::GetFecPacketsAsRed(
     int red_payload_type,
     int ulpfec_payload_type,
     uint16_t first_seq_num,
     size_t rtp_header_length) {
   std::vector<std::unique_ptr<RedPacket>> red_packets;
   red_packets.reserve(generated_fec_packets_.size());
   RTC_DCHECK(!media_packets_.empty());
   ForwardErrorCorrection::Packet* last_media_packet =
       media_packets_.back().get();
   uint16_t seq_num = first_seq_num;
   for (const auto& fec_packet : generated_fec_packets_) {
     // Wrap FEC packet (including FEC headers) in a RED packet. Since the
     // FEC packets in |generated_fec_packets_| don't have RTP headers, we
     // reuse the header from the last media packet.
     std::unique_ptr<RedPacket> red_packet(new RedPacket(
         fec_packet->length + kRedForFecHeaderLength + rtp_header_length));
     red_packet->CreateHeader(last_media_packet->data, rtp_header_length,
                              red_payload_type, ulpfec_payload_type);
     red_packet->SetSeqNum(seq_num++);
     red_packet->ClearMarkerBit();
     red_packet->AssignPayload(fec_packet->data, fec_packet->length);
-
     red_packets.push_back(std::move(red_packet));
   }
-
   // Reset state.
   DeleteMediaPackets();
   generated_fec_packets_.clear();
   num_protected_frames_ = 0;
-
   return red_packets;
 }
 
 int ProducerFec::Overhead() const {
   // Overhead is defined as relative to the number of media packets, and not
   // relative to total number of packets. This definition is inherited from the
   // protection factor produced by video_coding module and how the FEC
   // generation is implemented.
   RTC_DCHECK(!media_packets_.empty());
   int num_fec_packets =
-      fec_->GetNumberOfFecPackets(media_packets_.size(), params_.fec_rate);
+      fec_.NumFecPackets(media_packets_.size(), params_.fec_rate);
   // Return the overhead in Q8.
   return (num_fec_packets << 8) / media_packets_.size();
 }
 
 void ProducerFec::DeleteMediaPackets() {
   media_packets_.clear();
 }
 
 }  // namespace webrtc