1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "media/cast/net/rtp/rtp_header_parser.h" 6 7 #include <cstddef> 8 9 #include "base/big_endian.h" 10 11 namespace media { 12 namespace cast { 13 14 static const uint8 kCastKeyFrameBitMask = 0x80; 15 static const uint8 kCastReferenceFrameIdBitMask = 0x40; 16 static const size_t kRtpCommonHeaderLength = 12; 17 static const size_t kRtpCastHeaderLength = 12; 18 19 RtpCastTestHeader::RtpCastTestHeader() 20 : is_key_frame(false), 21 frame_id(0), 22 packet_id(0), 23 max_packet_id(0), 24 is_reference(false), 25 reference_frame_id(0), 26 marker(false), 27 sequence_number(0), 28 rtp_timestamp(0), 29 ssrc(0), 30 payload_type(0), 31 num_csrcs(0), 32 audio_num_energy(0), 33 header_length(0) {} 34 35 RtpCastTestHeader::~RtpCastTestHeader() {} 36 37 RtpHeaderParser::RtpHeaderParser(const uint8* rtp_data, size_t rtp_data_length) 38 : rtp_data_begin_(rtp_data), length_(rtp_data_length) {} 39 40 RtpHeaderParser::~RtpHeaderParser() {} 41 42 bool RtpHeaderParser::Parse(RtpCastTestHeader* parsed_packet) const { 43 if (length_ < kRtpCommonHeaderLength + kRtpCastHeaderLength) 44 return false; 45 if (!ParseCommon(parsed_packet)) 46 return false; 47 return ParseCast(parsed_packet); 48 } 49 50 bool RtpHeaderParser::ParseCommon(RtpCastTestHeader* parsed_packet) const { 51 const uint8 version = rtp_data_begin_[0] >> 6; 52 if (version != 2) { 53 return false; 54 } 55 56 const uint8 num_csrcs = rtp_data_begin_[0] & 0x0f; 57 const bool marker = ((rtp_data_begin_[1] & 0x80) == 0) ? false : true; 58 const uint8 payload_type = rtp_data_begin_[1] & 0x7f; 59 const uint16 sequence_number = (rtp_data_begin_[2] << 8) + rtp_data_begin_[3]; 60 61 const uint8* ptr = &rtp_data_begin_[4]; 62 63 base::BigEndianReader big_endian_reader(reinterpret_cast<const char*>(ptr), 64 8); 65 uint32 rtp_timestamp, ssrc; 66 big_endian_reader.ReadU32(&rtp_timestamp); 67 big_endian_reader.ReadU32(&ssrc); 68 69 const uint8 csrc_octs = num_csrcs * 4; 70 71 parsed_packet->marker = marker; 72 parsed_packet->payload_type = payload_type; 73 parsed_packet->sequence_number = sequence_number; 74 parsed_packet->rtp_timestamp = rtp_timestamp; 75 parsed_packet->ssrc = ssrc; 76 parsed_packet->num_csrcs = num_csrcs; 77 78 parsed_packet->audio_num_energy = parsed_packet->num_csrcs; 79 80 parsed_packet->header_length = 12 + csrc_octs; 81 return true; 82 } 83 84 bool RtpHeaderParser::ParseCast(RtpCastTestHeader* parsed_packet) const { 85 const uint8* data = rtp_data_begin_ + kRtpCommonHeaderLength; 86 parsed_packet->is_key_frame = (data[0] & kCastKeyFrameBitMask); 87 parsed_packet->is_reference = (data[0] & kCastReferenceFrameIdBitMask); 88 parsed_packet->frame_id = frame_id_wrap_helper_.MapTo32bitsFrameId(data[1]); 89 90 base::BigEndianReader big_endian_reader( 91 reinterpret_cast<const char*>(data + 2), 8); 92 big_endian_reader.ReadU16(&parsed_packet->packet_id); 93 big_endian_reader.ReadU16(&parsed_packet->max_packet_id); 94 95 if (parsed_packet->is_reference) { 96 parsed_packet->reference_frame_id = 97 reference_frame_id_wrap_helper_.MapTo32bitsFrameId(data[6]); 98 } 99 return true; 100 } 101 102 } // namespace cast 103 } // namespace media 104
