cast: cleanup rtp header and parsing

media/cast/net/rtp/rtp_packet_builder.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/cast/net/rtp/rtp_packet_builder.h"
 
 #include "base/big_endian.h"
 #include "base/logging.h"
 
 namespace media {
 namespace cast {
 
-const uint32 kCastRtpHeaderLength = 7;
-const uint32 kGenericRtpHeaderLength = 12;
-static const uint8 kRtpMarkerBitMask = 0x80;
-
 RtpPacketBuilder::RtpPacketBuilder()
     : is_key_(false),
       frame_id_(0),
       packet_id_(0),
       max_packet_id_(0),
       reference_frame_id_(0),
       timestamp_(0),
       sequence_number_(0),
       marker_(false),
       payload_type_(0),
@@ skipping 23 matching lines @@
 void RtpPacketBuilder::SetMarkerBit(bool marker) { marker_ = marker; }
 
 void RtpPacketBuilder::SetPayloadType(int payload_type) {
   payload_type_ = payload_type;
 }
 
 void RtpPacketBuilder::SetSsrc(uint32 ssrc) { ssrc_ = ssrc; }
 
 void RtpPacketBuilder::BuildHeader(uint8* data, uint32 data_length) {
   BuildCommonHeader(data, data_length);
-  BuildCastHeader(data + kGenericRtpHeaderLength,
-                  data_length - kGenericRtpHeaderLength);
+  BuildCastHeader(data + kRtpHeaderLength, data_length - kRtpHeaderLength);
 }
 
 void RtpPacketBuilder::BuildCastHeader(uint8* data, uint32 data_length) {
   // Build header.
-  DCHECK_LE(kCastRtpHeaderLength, data_length);
+  DCHECK_LE(kCastHeaderLength, data_length);
   // Set the first 7 bytes to 0.
-  memset(data, 0, kCastRtpHeaderLength);
+  memset(data, 0, kCastHeaderLength);
   base::BigEndianWriter big_endian_writer(reinterpret_cast<char*>(data), 56);
   const bool includes_specific_frame_reference =
       (is_key_ && (reference_frame_id_ != frame_id_)) ||
       (!is_key_ && (reference_frame_id_ != (frame_id_ - 1)));
   big_endian_writer.WriteU8((is_key_ ? 0x80 : 0) |
                             (includes_specific_frame_reference ? 0x40 : 0));
   big_endian_writer.WriteU8(frame_id_);
   big_endian_writer.WriteU16(packet_id_);
   big_endian_writer.WriteU16(max_packet_id_);
   if (includes_specific_frame_reference) {
     big_endian_writer.WriteU8(reference_frame_id_);
   }
 }
 
 void RtpPacketBuilder::BuildCommonHeader(uint8* data, uint32 data_length) {
-  DCHECK_LE(kGenericRtpHeaderLength, data_length);
+  DCHECK_LE(kRtpHeaderLength, data_length);
   base::BigEndianWriter big_endian_writer(reinterpret_cast<char*>(data), 96);
   big_endian_writer.WriteU8(0x80);
   big_endian_writer.WriteU8(payload_type_ | (marker_ ? kRtpMarkerBitMask : 0));
   big_endian_writer.WriteU16(sequence_number_);
   big_endian_writer.WriteU32(timestamp_);
   big_endian_writer.WriteU32(ssrc_);
 }
 
 }  // namespace cast
 }  // namespace media