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// 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/framer/cast_message_builder.h"
#include "media/cast/cast_defines.h"
namespace media {
namespace cast {
CastMessageBuilder::CastMessageBuilder(
base::TickClock* clock,
RtpPayloadFeedback* incoming_payload_feedback,
FrameIdMap* frame_id_map,
uint32 media_ssrc,
bool decoder_faster_than_max_frame_rate,
int max_unacked_frames)
: clock_(clock),
cast_feedback_(incoming_payload_feedback),
frame_id_map_(frame_id_map),
media_ssrc_(media_ssrc),
decoder_faster_than_max_frame_rate_(decoder_faster_than_max_frame_rate),
max_unacked_frames_(max_unacked_frames),
cast_msg_(media_ssrc),
waiting_for_key_frame_(true),
slowing_down_ack_(false),
acked_last_frame_(true),
last_acked_frame_id_(kStartFrameId) {
cast_msg_.ack_frame_id_ = kStartFrameId;
}
CastMessageBuilder::~CastMessageBuilder() {}
void CastMessageBuilder::CompleteFrameReceived(uint8 frame_id,
bool is_key_frame) {
if (last_update_time_.is_null()) {
// Our first update.
last_update_time_ = clock_->NowTicks();
}
if (waiting_for_key_frame_) {
if (!is_key_frame) {
// Ignore that we have received this complete frame since we are
// waiting on a key frame.
return;
}
waiting_for_key_frame_ = false;
cast_msg_.missing_frames_and_packets_.clear();
cast_msg_.ack_frame_id_ = frame_id;
last_update_time_ = clock_->NowTicks();
// We might have other complete frames waiting after we receive the last
// packet in the key-frame.
UpdateAckMessage();
} else {
if (!UpdateAckMessage()) return;
BuildPacketList();
}
// Send cast message.
VLOG(1) << "Send cast message Ack:" << static_cast<int>(frame_id);
cast_feedback_->CastFeedback(cast_msg_);
}
bool CastMessageBuilder::UpdateAckMessage() {
if (!decoder_faster_than_max_frame_rate_) {
int complete_frame_count = frame_id_map_->NumberOfCompleteFrames();
if (complete_frame_count > max_unacked_frames_) {
// We have too many frames pending in our framer; slow down ACK.
slowing_down_ack_ = true;
} else if (complete_frame_count <= 1) {
// We are down to one or less frames in our framer; ACK normally.
slowing_down_ack_ = false;
}
}
if (slowing_down_ack_) {
// We are slowing down acknowledgment by acknowledging every other frame.
if (acked_last_frame_) {
acked_last_frame_ = false;
} else {
acked_last_frame_ = true;
last_acked_frame_id_++;
// Note: frame skipping and slowdown ACK is not supported at the same
// time; and it's not needed since we can skip frames to catch up.
}
} else {
uint8 frame_id = frame_id_map_->LastContinuousFrame();
// Is it a new frame?
if (last_acked_frame_id_ == frame_id) return false;
last_acked_frame_id_ = frame_id;
acked_last_frame_ = true;
}
cast_msg_.ack_frame_id_ = last_acked_frame_id_;
cast_msg_.missing_frames_and_packets_.clear();
last_update_time_ = clock_->NowTicks();
return true;
}
bool CastMessageBuilder::TimeToSendNextCastMessage(
base::TimeTicks* time_to_send) {
// We haven't received any packets.
if (last_update_time_.is_null() && frame_id_map_->Empty()) return false;
*time_to_send = last_update_time_ +
base::TimeDelta::FromMilliseconds(kCastMessageUpdateIntervalMs);
return true;
}
void CastMessageBuilder::UpdateCastMessage() {
RtcpCastMessage message(media_ssrc_);
if (!UpdateCastMessageInternal(&message)) return;
// Send cast message.
cast_feedback_->CastFeedback(message);
}
void CastMessageBuilder::Reset() {
waiting_for_key_frame_ = true;
cast_msg_.ack_frame_id_ = kStartFrameId;
cast_msg_.missing_frames_and_packets_.clear();
time_last_nacked_map_.clear();
}
bool CastMessageBuilder::UpdateCastMessageInternal(RtcpCastMessage* message) {
if (last_update_time_.is_null()) {
if (!frame_id_map_->Empty()) {
// We have received packets.
last_update_time_ = clock_->NowTicks();
}
return false;
}
// Is it time to update the cast message?
base::TimeTicks now = clock_->NowTicks();
if (now - last_update_time_ <
base::TimeDelta::FromMilliseconds(kCastMessageUpdateIntervalMs)) {
return false;
}
last_update_time_ = now;
UpdateAckMessage(); // Needed to cover when a frame is skipped.
BuildPacketList();
*message = cast_msg_;
return true;
}
void CastMessageBuilder::BuildPacketList() {
base::TimeTicks now = clock_->NowTicks();
// Clear message NACK list.
cast_msg_.missing_frames_and_packets_.clear();
// Are we missing packets?
if (frame_id_map_->Empty()) return;
uint8 newest_frame_id = frame_id_map_->NewestFrameId();
uint8 next_expected_frame_id =
static_cast<uint8>(cast_msg_.ack_frame_id_ + 1);
// Iterate over all frames.
for (; !IsNewerFrameId(next_expected_frame_id, newest_frame_id);
++next_expected_frame_id) {
TimeLastNackMap::iterator it =
time_last_nacked_map_.find(next_expected_frame_id);
if (it != time_last_nacked_map_.end()) {
// We have sent a NACK in this frame before, make sure enough time have
// passed.
if (now - it->second <
base::TimeDelta::FromMilliseconds(kNackRepeatIntervalMs)) {
continue;
}
}
PacketIdSet missing;
if (frame_id_map_->FrameExists(next_expected_frame_id)) {
bool last_frame = (newest_frame_id == next_expected_frame_id);
frame_id_map_->GetMissingPackets(next_expected_frame_id, last_frame,
&missing);
if (!missing.empty()) {
time_last_nacked_map_[next_expected_frame_id] = now;
cast_msg_.missing_frames_and_packets_.insert(
std::make_pair(next_expected_frame_id, missing));
}
} else {
time_last_nacked_map_[next_expected_frame_id] = now;
missing.insert(kRtcpCastAllPacketsLost);
cast_msg_.missing_frames_and_packets_[next_expected_frame_id] = missing;
}
}
}
} // namespace cast
} // namespace media
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