video_coding::PacketBuffer now group all H264 packets with the same timestamp into the same frame.

webrtc/modules/video_coding/packet_buffer.cc

Index: webrtc/modules/video_coding/packet_buffer.cc
diff --git a/webrtc/modules/video_coding/packet_buffer.cc b/webrtc/modules/video_coding/packet_buffer.cc
index 452e762b9f10c5c41392e81bf95531124da95e8e..ca1b090d26901bd81d2b1c4d52cf6fe52661a7ec 100644
--- a/webrtc/modules/video_coding/packet_buffer.cc
+++ b/webrtc/modules/video_coding/packet_buffer.cc
@@ -211,17 +211,27 @@ std::vector<std::unique_ptr<RtpFrameObject>> PacketBuffer::FindFrames(
       // Find the start index by searching backward until the packet with
       // the |frame_begin| flag is set.
       int start_index = index;
+
+      bool is_h264 = data_buffer_[start_index].codec == kVideoCodecH264;
+      int64_t frame_timestamp = data_buffer_[start_index].timestamp;
       while (true) {
         frame_size += data_buffer_[start_index].sizeBytes;
         max_nack_count =
             std::max(max_nack_count, data_buffer_[start_index].timesNacked);
         sequence_buffer_[start_index].frame_created = true;
 
-        if (sequence_buffer_[start_index].frame_begin)
+        if (!is_h264 && sequence_buffer_[start_index].frame_begin)
           break;
 
         start_index = start_index > 0 ? start_index - 1 : size_ - 1;
-        start_seq_num--;
+
+        if (is_h264 && start_index != static_cast<int>(index) &&

[stefan-webrtc, 2017/02/02 15:19:00]

Can we have a short comment on what this is trying to achieve? It's a bit hard
for a reader to interpret.

Is it something like "Beginning of an h.264 frame has been reached if the
timestamp changes and the begin bit has been found on the previous packet."? 
Why is that not true for all codecs? And do we know that the previous packet had
a begin bit?

[philipel, 2017/02/02 15:47:37]

Added a comment about it.

+            (!sequence_buffer_[start_index].used ||
+             data_buffer_[start_index].timestamp != frame_timestamp)) {
+          break;
+        }
+
+        --start_seq_num;
       }
 
       found_frames.emplace_back(