1 files changed, 107 insertions, 0 deletions
diff --git a/media/cast/rtp_receiver/rtp_parser/rtp_parser.cc b/media/cast/rtp_receiver/rtp_parser/rtp_parser.cc
new file mode 100644
index 0000000..0eb691b
--- /dev/null
+++ b/media/cast/rtp_receiver/rtp_parser/rtp_parser.cc
@@ -0,0 +1,107 @@
+// Copyright 2013 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/rtp_receiver/rtp_parser/rtp_parser.h"
+
+#include "base/logging.h"
+#include "media/cast/cast_defines.h"
+#include "media/cast/rtp_receiver/rtp_receiver.h"
+#include "net/base/big_endian.h"
+
+namespace media {
+namespace cast {
+
+static const int kRtpCommonHeaderLength = 12;
+static const int kRtpCastHeaderLength = 7;
+static const uint8 kCastKeyFrameBitMask = 0x80;
+static const uint8 kCastReferenceFrameIdBitMask = 0x40;
+
+RtpParser::RtpParser(RtpData* incoming_payload_callback,
+                     const RtpParserConfig parser_config)
+    : data_callback_(incoming_payload_callback),
+      parser_config_(parser_config) {
+}
+
+RtpParser::~RtpParser() {
+}
+
+bool RtpParser::ParsePacket(const uint8* packet, int length,
+                            RtpCastHeader* rtp_header) {
+  if (length == 0) return false;
+  // Get RTP general header.
+  if (!ParseCommon(packet, length, rtp_header)) return false;
+  if (rtp_header->webrtc.header.payloadType == parser_config_.payload_type &&
+    rtp_header->webrtc.header.ssrc == parser_config_.ssrc) {
+    return ParseCast(packet + kRtpCommonHeaderLength,
+        length - kRtpCommonHeaderLength, rtp_header);
+  }
+  // Not a valid payload type / ssrc combination.
+  return false;
+}
+
+bool RtpParser::ParseCommon(const uint8* packet,
+                            int length,
+                            RtpCastHeader* rtp_header) {
+  if (length < kRtpCommonHeaderLength) return false;
+  uint8 version = packet[0] >> 6;
+  if (version != 2) return false;
+  uint8 cc = packet[0] & 0x0f;
+  bool marker = ((packet[1] & 0x80) != 0);
+  int payload_type = packet[1] & 0x7f;
+
+  uint16 sequence_number;
+  uint32 rtp_timestamp, ssrc;
+  net::BigEndianReader big_endian_reader(packet + 2, 80);
+  big_endian_reader.ReadU16(&sequence_number);
+  big_endian_reader.ReadU32(&rtp_timestamp);
+  big_endian_reader.ReadU32(&ssrc);
+
+  rtp_header->webrtc.header.markerBit      = marker;
+  rtp_header->webrtc.header.payloadType    = payload_type;
+  rtp_header->webrtc.header.sequenceNumber = sequence_number;
+  rtp_header->webrtc.header.timestamp      = rtp_timestamp;
+  rtp_header->webrtc.header.ssrc           = ssrc;
+  rtp_header->webrtc.header.numCSRCs       = cc;
+
+  uint8 csrc_octs = cc * 4;
+  rtp_header->webrtc.type.Audio.numEnergy = rtp_header->webrtc.header.numCSRCs;
+  rtp_header->webrtc.header.headerLength = kRtpCommonHeaderLength + csrc_octs;
+  rtp_header->webrtc.type.Audio.isCNG = false;
+  rtp_header->webrtc.type.Audio.channel = parser_config_.audio_channels;
+  return true;
+}
+
+bool RtpParser::ParseCast(const uint8* packet,
+                          int length,
+                          RtpCastHeader* rtp_header) {
+  if (length < kRtpCastHeaderLength) return false;
+  // Extract header.
+  const uint8* data_ptr = packet;
+  int data_length = length;
+  rtp_header->is_key_frame = (data_ptr[0] & kCastKeyFrameBitMask);
+  rtp_header->is_reference = (data_ptr[0] & kCastReferenceFrameIdBitMask);
+  rtp_header->frame_id = data_ptr[1];
+
+  net::BigEndianReader big_endian_reader(data_ptr + 2, 32);
+  big_endian_reader.ReadU16(&rtp_header->packet_id);
+  big_endian_reader.ReadU16(&rtp_header->max_packet_id);
+
+  if (rtp_header->is_reference) {
+    rtp_header->reference_frame_id = data_ptr[6];
+    data_ptr += kRtpCastHeaderLength;
+    data_length -= kRtpCastHeaderLength;
+  } else {
+    data_ptr += kRtpCastHeaderLength - 1;
+    data_length -= kRtpCastHeaderLength - 1;
+  }
+
+  if (rtp_header->max_packet_id < rtp_header->packet_id) {
+    return false;
+  }
+  data_callback_->OnReceivedPayloadData(data_ptr, data_length, rtp_header);
+  return true;
+}
+
+}  // namespace cast
+}  // namespace media