Convert Vp8 Rtp headers to frame references.

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.
  */
 
 #ifndef WEBRTC_MODULES_VIDEO_CODING_PACKET_BUFFER_H_
 #define WEBRTC_MODULES_VIDEO_CODING_PACKET_BUFFER_H_
 
+#include <array>
 #include <vector>
+#include <map>
+#include <set>
+#include <queue>
 
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/scoped_ptr.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/modules/video_coding/packet.h"
+#include "webrtc/modules/video_coding/sequence_number_util.h"
 
 namespace webrtc {
 namespace video_coding {
 
 class FrameObject;
 class RtpFrameObject;
 
 class OnCompleteFrameCallback {
  public:
   virtual ~OnCompleteFrameCallback() {}
   virtual void OnCompleteFrame(std::unique_ptr<FrameObject> frame) = 0;
 };
 
 class PacketBuffer {
  public:
   // Both |start_buffer_size| and |max_buffer_size| must be a power of 2.
   PacketBuffer(size_t start_buffer_size,
                size_t max_buffer_size,
                OnCompleteFrameCallback* frame_callback);
 
   bool InsertPacket(const VCMPacket& packet);
   void ClearTo(uint16_t seq_num);
   void Flush();
 
  private:
+  static const uint16_t kPicIdLength = 1 << 7;
+  static const uint8_t kMaxTemporalLayer = 5;
+
   friend RtpFrameObject;
   // Since we want the packet buffer to be as packet type agnostic
   // as possible we extract only the information needed in order
-  // to determin whether a sequence of packets is continuous or not.
+  // to determine whether a sequence of packets is continuous or not.
   struct ContinuityInfo {
+    // 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;
+
+    // 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;
   };
 
+  // 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_);
-  void FindCompleteFrames(uint16_t seq_num) 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|.
   bool GetBitstream(const RtpFrameObject& frame, uint8_t* destination);
+
+  // Mark all slots used by |frame| as not used.
   void ReturnFrame(RtpFrameObject* frame);
 
+  // Find the references for this frame.
+  void ManageFrame(std::unique_ptr<RtpFrameObject> frame)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
+  // Retry finding references for all frames that previously didn't have
+  // all information needed.
+  void RetryStashedFrames() EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
+  // Find references for generic frames.
+  void ManageFrameGeneric(std::unique_ptr<RtpFrameObject> frame)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
+  // Find references for Vp8 frames
+  void ManageFrameVp8(std::unique_ptr<RtpFrameObject> frame)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
+  // Updates all necessary state used to determine frame references
+  // for Vp8 and then calls the |frame_callback| callback with the
+  // completed frame.
+  void CompletedFrameVp8(std::unique_ptr<RtpFrameObject> frame)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
+  // All picture ids are unwrapped to 16 bits.
+  uint16_t UnwrapPictureId(uint16_t picture_id)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_);
+
   rtc::CriticalSection crit_;
 
   // Buffer size_ and max_size_ must always be a power of two.
   size_t size_ GUARDED_BY(crit_);
   const size_t max_size_;
 
+  // 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_);
-  uint16_t first_seq_num_ GUARDED_BY(crit_);
-  bool initialized_ GUARDED_BY(crit_);
+
+  // If the packet buffer has received its first packet.
+  bool first_packet_received_ 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_);
 
+  // The callback that is called when a frame has been created and all its
+  // references has been found.
   OnCompleteFrameCallback* const frame_callback_;
+
+  // Holds the last sequence number of the last frame that has been created
+  // given the last sequence number of a given keyframe.
+  std::map<uint16_t, uint16_t, DescendingSeqNumComp<uint16_t>>
+    last_seq_num_for_kf_ GUARDED_BY(crit_);

[stefan-webrtc, 2016/04/07 12:37:04]

I think this is a bit confusing. If I have received a key frame with last seq
num 10, and then I receive a frame with last seq num 11, will
last_seq_num_for_kf_[10] == 11 then? And if I receive another frame with last
seq num 12 it will be updated to 12?

[philipel, 2016/04/07 13:38:42]

That is exactly how it works.

+
+  // Save the last picture id in order to detect when there is a gap in frames
+  // that has not yet been fully received.

[stefan-webrtc, 2016/04/07 12:37:04]

that have not yet

[philipel, 2016/04/07 13:38:42]

Done.

+  int last_picture_id_ GUARDED_BY(crit_);

[stefan-webrtc, 2016/04/07 12:37:04]

Is this the last received picture id or the last completed picture id?

[philipel, 2016/04/07 13:38:42]

The |last_picture_id_| is the id of the last frame that has received all of its
packets.

+
+  // The last unwrapped picture id. Used to unwrap the picture id from a length
+  // of |kPicIdLength| to 16 bits.
+  int last_unwrap_ GUARDED_BY(crit_);
+
+  // Frames earlier than the last received frame that has not yet been

[stefan-webrtc, 2016/04/07 12:37:04]

...that have not yet...

[philipel, 2016/04/07 13:38:42]

Done.

+  // fully received.
+  std::set<uint8_t, DescendingSeqNumComp<uint8_t, kPicIdLength>>
+    not_yet_received_frames_ GUARDED_BY(crit_);
+
+  // Frames that has been fully received but didn't have all the information

[stefan-webrtc, 2016/04/07 12:37:04]

Frames that have been

[philipel, 2016/04/07 13:38:42]

Done.

+  // needed to determine its references.

[stefan-webrtc, 2016/04/07 12:37:04]

their references.

[philipel, 2016/04/07 13:38:42]

Done.

+  std::queue<std::unique_ptr<RtpFrameObject>> stashed_frames_ GUARDED_BY(crit_);
+
+  // Holds the information about the last completed frame for a given temporal
+  // layer given a Tl0 picture index.
+  std::map<uint8_t,
+          std::array<int16_t, kMaxTemporalLayer>,
+          DescendingSeqNumComp<uint8_t>> layer_info_ GUARDED_BY(crit_);
 };
 
 }  // namespace video_coding
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_PACKET_BUFFER_H_