1 // Copyright 2013 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.
5 #include "media/cast/framer/cast_message_builder.h"
7 #include "media/cast/cast_defines.h"
12 CastMessageBuilder::CastMessageBuilder(
13 base::TickClock* clock,
14 RtpPayloadFeedback* incoming_payload_feedback,
15 FrameIdMap* frame_id_map,
17 bool decoder_faster_than_max_frame_rate,
18 int max_unacked_frames)
20 cast_feedback_(incoming_payload_feedback),
21 frame_id_map_(frame_id_map),
22 media_ssrc_(media_ssrc),
23 decoder_faster_than_max_frame_rate_(decoder_faster_than_max_frame_rate),
24 max_unacked_frames_(max_unacked_frames),
25 cast_msg_(media_ssrc),
26 waiting_for_key_frame_(true),
27 slowing_down_ack_(false),
28 acked_last_frame_(true),
29 last_acked_frame_id_(kStartFrameId) {
30 cast_msg_.ack_frame_id_ = kStartFrameId;
33 CastMessageBuilder::~CastMessageBuilder() {}
35 void CastMessageBuilder::CompleteFrameReceived(uint8 frame_id,
37 if (last_update_time_.is_null()) {
39 last_update_time_ = clock_->NowTicks();
41 if (waiting_for_key_frame_) {
43 // Ignore that we have received this complete frame since we are
44 // waiting on a key frame.
47 waiting_for_key_frame_ = false;
48 cast_msg_.missing_frames_and_packets_.clear();
49 cast_msg_.ack_frame_id_ = frame_id;
50 last_update_time_ = clock_->NowTicks();
51 // We might have other complete frames waiting after we receive the last
52 // packet in the key-frame.
55 if (!UpdateAckMessage()) return;
60 VLOG(1) << "Send cast message Ack:" << static_cast<int>(frame_id);
61 cast_feedback_->CastFeedback(cast_msg_);
64 bool CastMessageBuilder::UpdateAckMessage() {
65 if (!decoder_faster_than_max_frame_rate_) {
66 int complete_frame_count = frame_id_map_->NumberOfCompleteFrames();
67 if (complete_frame_count > max_unacked_frames_) {
68 // We have too many frames pending in our framer; slow down ACK.
69 slowing_down_ack_ = true;
70 } else if (complete_frame_count <= 1) {
71 // We are down to one or less frames in our framer; ACK normally.
72 slowing_down_ack_ = false;
75 if (slowing_down_ack_) {
76 // We are slowing down acknowledgment by acknowledging every other frame.
77 if (acked_last_frame_) {
78 acked_last_frame_ = false;
80 acked_last_frame_ = true;
81 last_acked_frame_id_++;
82 // Note: frame skipping and slowdown ACK is not supported at the same
83 // time; and it's not needed since we can skip frames to catch up.
86 uint8 frame_id = frame_id_map_->LastContinuousFrame();
89 if (last_acked_frame_id_ == frame_id) return false;
91 last_acked_frame_id_ = frame_id;
92 acked_last_frame_ = true;
94 cast_msg_.ack_frame_id_ = last_acked_frame_id_;
95 cast_msg_.missing_frames_and_packets_.clear();
96 last_update_time_ = clock_->NowTicks();
100 bool CastMessageBuilder::TimeToSendNextCastMessage(
101 base::TimeTicks* time_to_send) {
102 // We haven't received any packets.
103 if (last_update_time_.is_null() && frame_id_map_->Empty()) return false;
105 *time_to_send = last_update_time_ +
106 base::TimeDelta::FromMilliseconds(kCastMessageUpdateIntervalMs);
110 void CastMessageBuilder::UpdateCastMessage() {
111 RtcpCastMessage message(media_ssrc_);
112 if (!UpdateCastMessageInternal(&message)) return;
114 // Send cast message.
115 cast_feedback_->CastFeedback(message);
118 void CastMessageBuilder::Reset() {
119 waiting_for_key_frame_ = true;
120 cast_msg_.ack_frame_id_ = kStartFrameId;
121 cast_msg_.missing_frames_and_packets_.clear();
122 time_last_nacked_map_.clear();
125 bool CastMessageBuilder::UpdateCastMessageInternal(RtcpCastMessage* message) {
126 if (last_update_time_.is_null()) {
127 if (!frame_id_map_->Empty()) {
128 // We have received packets.
129 last_update_time_ = clock_->NowTicks();
133 // Is it time to update the cast message?
134 base::TimeTicks now = clock_->NowTicks();
135 if (now - last_update_time_ <
136 base::TimeDelta::FromMilliseconds(kCastMessageUpdateIntervalMs)) {
139 last_update_time_ = now;
141 UpdateAckMessage(); // Needed to cover when a frame is skipped.
143 *message = cast_msg_;
147 void CastMessageBuilder::BuildPacketList() {
148 base::TimeTicks now = clock_->NowTicks();
150 // Clear message NACK list.
151 cast_msg_.missing_frames_and_packets_.clear();
153 // Are we missing packets?
154 if (frame_id_map_->Empty()) return;
156 uint8 newest_frame_id = frame_id_map_->NewestFrameId();
157 uint8 next_expected_frame_id =
158 static_cast<uint8>(cast_msg_.ack_frame_id_ + 1);
160 // Iterate over all frames.
161 for (; !IsNewerFrameId(next_expected_frame_id, newest_frame_id);
162 ++next_expected_frame_id) {
163 TimeLastNackMap::iterator it =
164 time_last_nacked_map_.find(next_expected_frame_id);
165 if (it != time_last_nacked_map_.end()) {
166 // We have sent a NACK in this frame before, make sure enough time have
168 if (now - it->second <
169 base::TimeDelta::FromMilliseconds(kNackRepeatIntervalMs)) {
175 if (frame_id_map_->FrameExists(next_expected_frame_id)) {
176 bool last_frame = (newest_frame_id == next_expected_frame_id);
177 frame_id_map_->GetMissingPackets(next_expected_frame_id, last_frame,
179 if (!missing.empty()) {
180 time_last_nacked_map_[next_expected_frame_id] = now;
181 cast_msg_.missing_frames_and_packets_.insert(
182 std::make_pair(next_expected_frame_id, missing));
185 time_last_nacked_map_[next_expected_frame_id] = now;
186 missing.insert(kRtcpCastAllPacketsLost);
187 cast_msg_.missing_frames_and_packets_[next_expected_frame_id] = missing;