Only advance |first_seq_num_| if packets are explicitly cleared from the PacketBuffer.

webrtc/modules/video_coding/packet_buffer.h

 /*
  *  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.
  */
 
@@ skipping 61 matching lines @@
     // The sequence number of the packet.
     uint16_t seq_num = 0;
 
     // If this is the first packet of the frame.
     bool frame_begin = false;
 
     // If this is the last packet of the frame.
     bool frame_end = false;
 
     // If this slot is currently used.
     bool used = false;

[danilchap, 2016/10/07 18:25:37]

seq_buffer[index].used = true <=> data_buffer[index].dataPtr != nullptr?
if that the case, may be remove used and check dataPtr directly.

[danilchap, 2016/10/19 09:25:10]

please ack if you disagree

[philipel, 2016/10/19 13:08:50]

seq_buffer[index].used = true <=> data_buffer[index].dataPtr != nullptr is true,
but I'm not sure if I want to remove |used| from ContinuityInfo. If we remove it
then I think that should be done in another CL.

 
     // If all its previous packets have been inserted into the packet buffer.
     bool continuous = false;
 
     // If this packet has been used to create a frame already.
     bool frame_created = false;
   };
 
   Clock* const clock_;
 
   // Tries to expand the buffer.
   bool ExpandBufferSize() EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   // Test if all previous packets has arrived for the given sequence number.
-  bool IsContinuous(uint16_t seq_num) const EXCLUSIVE_LOCKS_REQUIRED(crit_);
+  bool PotentialNewFrame(uint16_t seq_num) const
+      EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   // Test if all packets of a frame has arrived, and if so, creates a frame.
   // May create multiple frames per invocation.
   void FindFrames(uint16_t seq_num) EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   // Copy the bitstream for |frame| to |destination|.
   // Virtual for testing.
   virtual bool GetBitstream(const RtpFrameObject& frame, uint8_t* destination);
 
   // Get the packet with sequence number |seq_num|.
@@ skipping 12 matching lines @@
 
   // The fist sequence number currently in the buffer.
   uint16_t first_seq_num_ GUARDED_BY(crit_);
 
   // The last sequence number currently in the buffer.
   uint16_t last_seq_num_ GUARDED_BY(crit_);
 
   // If the packet buffer has received its first packet.
   bool first_packet_received_ GUARDED_BY(crit_);
 
+  // If the buffer is cleared to a specific packet.

[danilchap, 2016/10/07 18:25:37]

can you write what packet it cleared to, to first_seq_num_?

[philipel, 2016/10/18 12:22:19]

Done.

[danilchap, 2016/10/19 09:25:10]

Can't see the difference.

[philipel, 2016/10/19 13:08:50]

Double Done.

+  bool has_cleared_to_ GUARDED_BY(crit_);
+
   // Buffer that holds the inserted packets.
   std::vector<VCMPacket> data_buffer_ GUARDED_BY(crit_);
 
   // Buffer that holds the information about which slot that is currently in use
   // and information needed to determine the continuity between packets.
   std::vector<ContinuityInfo> sequence_buffer_ GUARDED_BY(crit_);
 
   // Called when a received frame is found.
   OnReceivedFrameCallback* const received_frame_callback_;
 
   mutable volatile int ref_count_ = 0;
 };
 
 }  // namespace video_coding
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_PACKET_BUFFER_H_