Using different sequence numbers for different SSRCs

webrtc/test/layer_filtering_transport.cc

 /*
  *  Copyright (c) 2015 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 11 matching lines @@
 LayerFilteringTransport::LayerFilteringTransport(
     const FakeNetworkPipe::Config& config,
     uint8_t vp8_video_payload_type,
     uint8_t vp9_video_payload_type,
     uint8_t tl_discard_threshold,
     uint8_t sl_discard_threshold)
     : test::DirectTransport(config),
       vp8_video_payload_type_(vp8_video_payload_type),
       vp9_video_payload_type_(vp9_video_payload_type),
       tl_discard_threshold_(tl_discard_threshold),
-      sl_discard_threshold_(sl_discard_threshold),
-      current_seq_num_(10000) {
-}  // TODO(ivica): random seq num?
+      sl_discard_threshold_(sl_discard_threshold) {
+}
+
+uint16_t LayerFilteringTransport::NextSequenceNumber(uint32_t ssrc) {
+  auto it = current_seq_nums_.find(ssrc);
+  if (it == current_seq_nums_.end())
+    return current_seq_nums_[ssrc] = 10000;
+  return ++it->second;
+}
 
 bool LayerFilteringTransport::SendRtp(const uint8_t* packet,
                                       size_t length,
                                       const PacketOptions& options) {
   if (tl_discard_threshold_ == 0 && sl_discard_threshold_ == 0) {
     // Nothing to change, forward the packet immediately.
     return test::DirectTransport::SendRtp(packet, length, options);
   }
 
   bool set_marker_bit = false;
@@ skipping 36 matching lines @@
       RTC_NOTREACHED() << "Parse error";
     }
   }
 
   uint8_t temp_buffer[IP_PACKET_SIZE];
   memcpy(temp_buffer, packet, length);
 
   // We are discarding some of the packets (specifically, whole layers), so
   // make sure the marker bit is set properly, and that sequence numbers are
   // continuous.
-  if (set_marker_bit) {
+  if (set_marker_bit)
     temp_buffer[1] |= kRtpMarkerBitMask;
-  }
-  ByteWriter<uint16_t>::WriteBigEndian(&temp_buffer[2], current_seq_num_);
 
-  ++current_seq_num_;  // Increase only if packet not discarded.
-
+  uint16_t seq_num = NextSequenceNumber(header.ssrc);
+  ByteWriter<uint16_t>::WriteBigEndian(&temp_buffer[2], seq_num);
   return test::DirectTransport::SendRtp(temp_buffer, length, options);
 }
 
 }  // namespace test
 }  // namespace webrtc