rtp_packet_builder.cc revision 116680a4aac90f2aa7413d9095a592090648e557
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_packet_builder.h" 6 7#include "base/big_endian.h" 8#include "base/logging.h" 9 10namespace media { 11namespace cast { 12 13const uint32 kCastRtpHeaderLength = 7; 14const uint32 kGenericRtpHeaderLength = 12; 15static const uint8 kRtpMarkerBitMask = 0x80; 16 17RtpPacketBuilder::RtpPacketBuilder() 18 : is_key_(false), 19 frame_id_(0), 20 packet_id_(0), 21 max_packet_id_(0), 22 reference_frame_id_(0), 23 timestamp_(0), 24 sequence_number_(0), 25 marker_(false), 26 payload_type_(0), 27 ssrc_(0) {} 28 29void RtpPacketBuilder::SetKeyFrame(bool is_key) { is_key_ = is_key; } 30 31void RtpPacketBuilder::SetFrameIds(uint32 frame_id, uint32 reference_frame_id) { 32 frame_id_ = frame_id; 33 reference_frame_id_ = reference_frame_id; 34} 35 36void RtpPacketBuilder::SetPacketId(uint16 packet_id) { packet_id_ = packet_id; } 37 38void RtpPacketBuilder::SetMaxPacketId(uint16 max_packet_id) { 39 max_packet_id_ = max_packet_id; 40} 41 42void RtpPacketBuilder::SetTimestamp(uint32 timestamp) { 43 timestamp_ = timestamp; 44} 45 46void RtpPacketBuilder::SetSequenceNumber(uint16 sequence_number) { 47 sequence_number_ = sequence_number; 48} 49 50void RtpPacketBuilder::SetMarkerBit(bool marker) { marker_ = marker; } 51 52void RtpPacketBuilder::SetPayloadType(int payload_type) { 53 payload_type_ = payload_type; 54} 55 56void RtpPacketBuilder::SetSsrc(uint32 ssrc) { ssrc_ = ssrc; } 57 58void RtpPacketBuilder::BuildHeader(uint8* data, uint32 data_length) { 59 BuildCommonHeader(data, data_length); 60 BuildCastHeader(data + kGenericRtpHeaderLength, 61 data_length - kGenericRtpHeaderLength); 62} 63 64void RtpPacketBuilder::BuildCastHeader(uint8* data, uint32 data_length) { 65 // Build header. 66 DCHECK_LE(kCastRtpHeaderLength, data_length); 67 // Set the first 7 bytes to 0. 68 memset(data, 0, kCastRtpHeaderLength); 69 base::BigEndianWriter big_endian_writer(reinterpret_cast<char*>(data), 56); 70 const bool includes_specific_frame_reference = 71 (is_key_ && (reference_frame_id_ != frame_id_)) || 72 (!is_key_ && (reference_frame_id_ != (frame_id_ - 1))); 73 big_endian_writer.WriteU8((is_key_ ? 0x80 : 0) | 74 (includes_specific_frame_reference ? 0x40 : 0)); 75 big_endian_writer.WriteU8(frame_id_); 76 big_endian_writer.WriteU16(packet_id_); 77 big_endian_writer.WriteU16(max_packet_id_); 78 if (includes_specific_frame_reference) { 79 big_endian_writer.WriteU8(reference_frame_id_); 80 } 81} 82 83void RtpPacketBuilder::BuildCommonHeader(uint8* data, uint32 data_length) { 84 DCHECK_LE(kGenericRtpHeaderLength, data_length); 85 base::BigEndianWriter big_endian_writer(reinterpret_cast<char*>(data), 96); 86 big_endian_writer.WriteU8(0x80); 87 big_endian_writer.WriteU8(payload_type_ | (marker_ ? kRtpMarkerBitMask : 0)); 88 big_endian_writer.WriteU16(sequence_number_); 89 big_endian_writer.WriteU32(timestamp_); 90 big_endian_writer.WriteU32(ssrc_); 91} 92 93} // namespace cast 94} // namespace media 95