New rtc dump analyzing tool in Python

tools/py_event_log_analyzer/pb_parse.py

+#  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.
+
+"""Parses protobuf RTC dumps.
+"""
+
+from __future__ import division
+
+import os
+import struct
+import sys
+
+
+# makes sure to import correct protobuf
+webrtc_root = "../../"
+sys.path.append(os.path.join(webrtc_root, "out/Debug/pyproto/webrtc/call/"))
+sys.path.append(os.path.join(webrtc_root, "out/Release/pyproto/webrtc/call/"))
+sys.path.append(os.path.join(webrtc_root, "third_party/protobuf/python/"))
+import rtc_event_log_pb2 as rtc_pb
+
+
+class DataPoint(object):
+  """Simple container class for RTP events.
+  """
+
+  def __init__(self, rtp_header_str, packet_size,
+               arrival_timestamp_us):
+    """Builds a data point by parsing an RTP header.
+
+    As defined in RFC 3550 section 5.1.

[hlundin-webrtc, 2016/05/25 12:54:23]

Technically, the arrival timestamp is not part of the RFC.

[aleloi2, 2016/05/30 14:57:55]

Updated a little.

+    """
+    self.size = packet_size
+    self.arrival_timestamp_ms = arrival_timestamp_us / 1000
+    unpacked = struct.unpack_from("!HHII", rtp_header_str, 0)
+    (first2header_bytes, self.sequence_number,
+     self.timestamp, self.ssrc
+    ) = unpacked

[kwiberg-webrtc, 2016/05/25 12:42:41]

Eliminate "unpacked"?

(first2header_bytes, self.sequence_number, self.timestamp,
 self.ssrc) = struct.unpack_from("!HHII", rtp_header_str, 0)

[aleloi2, 2016/05/30 14:57:55]

Done.

+    self.payload_type = first2header_bytes & 0b01111111
+
+
+def parse_protobuf(file_path):
+  """Parses rtc event log from protobuf file.

[peah-webrtc, 2016/05/26 06:44:18]

I think the abbreviation rtc should be capitalized.

[aleloi2, 2016/05/30 14:57:55]

Done.

+
+  Args:
+       file_path: path to protobuf file of RTC event stream
+
+  Returns:
+    all RtpPacket events from the event stream as a list of DataPoints

[peah-webrtc, 2016/05/26 06:44:18]

Rtp should be capitalized according to how it is capitalized elsewhere herein.
My suggestion would be to write this as RTP packet, or if matching the field
name below, as rtp_packet.

[aleloi2, 2016/05/30 14:57:55]

Done.

+  """
+  event_stream = rtc_pb.EventStream()
+  with open(file_path, "rb") as f:
+    event_stream.ParseFromString(f.read())
+
+  return [DataPoint(event.rtp_packet.header,
+                    event.rtp_packet.packet_length,
+                    event.timestamp_us)
+          for event in event_stream.stream
+          if event.HasField("rtp_packet")]