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