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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/rtp_sender/rtp_packetizer/rtp_packetizer.h"
#include "base/logging.h"
#include "media/cast/cast_defines.h"
#include "media/cast/pacing/paced_sender.h"
#include "net/base/big_endian.h"
namespace media {
namespace cast {
static const uint16 kCommonRtpHeaderLength = 12;
static const uint16 kCastRtpHeaderLength = 7;
static const uint8 kCastKeyFrameBitMask = 0x80;
static const uint8 kCastReferenceFrameIdBitMask = 0x40;
RtpPacketizer::RtpPacketizer(PacedPacketSender* transport,
PacketStorage* packet_storage,
RtpPacketizerConfig rtp_packetizer_config)
: config_(rtp_packetizer_config),
transport_(transport),
packet_storage_(packet_storage),
sequence_number_(config_.sequence_number),
rtp_timestamp_(config_.rtp_timestamp),
frame_id_(0),
packet_id_(0),
send_packets_count_(0),
send_octet_count_(0) {
DCHECK(transport) << "Invalid argument";
}
RtpPacketizer::~RtpPacketizer() {}
void RtpPacketizer::IncomingEncodedVideoFrame(
const EncodedVideoFrame* video_frame,
const base::TimeTicks& capture_time) {
DCHECK(!config_.audio) << "Invalid state";
if (config_.audio) return;
base::TimeTicks zero_time;
base::TimeDelta capture_delta = capture_time - zero_time;
// Timestamp is in 90 KHz for video.
rtp_timestamp_ = static_cast<uint32>(capture_delta.InMilliseconds() * 90);
time_last_sent_rtp_timestamp_ = capture_time;
Cast(video_frame->key_frame,
video_frame->last_referenced_frame_id,
rtp_timestamp_,
video_frame->data);
}
void RtpPacketizer::IncomingEncodedAudioFrame(
const EncodedAudioFrame* audio_frame,
const base::TimeTicks& recorded_time) {
DCHECK(config_.audio) << "Invalid state";
if (!config_.audio) return;
rtp_timestamp_ += audio_frame->samples; // Timestamp is in samples for audio.
time_last_sent_rtp_timestamp_ = recorded_time;
Cast(true, 0, rtp_timestamp_, audio_frame->data);
}
uint16 RtpPacketizer::NextSequenceNumber() {
++sequence_number_;
return sequence_number_ - 1;
}
bool RtpPacketizer::LastSentTimestamp(base::TimeTicks* time_sent,
uint32* rtp_timestamp) const {
if (time_last_sent_rtp_timestamp_.is_null()) return false;
*time_sent = time_last_sent_rtp_timestamp_;
*rtp_timestamp = rtp_timestamp_;
return true;
}
void RtpPacketizer::Cast(bool is_key,
uint8 reference_frame_id,
uint32 timestamp,
std::vector<uint8> data) {
uint16 rtp_header_length = kCommonRtpHeaderLength + kCastRtpHeaderLength;
uint16 max_length = config_.max_payload_length - rtp_header_length - 1;
// Split the payload evenly (round number up).
uint32 num_packets = (data.size() + max_length) / max_length;
uint32 payload_length = (data.size() + num_packets) / num_packets;
DCHECK_LE(payload_length, max_length) << "Invalid argument";
std::vector<uint8> packet;
packet.reserve(kIpPacketSize);
size_t remaining_size = data.size();
uint8* data_ptr = data.data();
while (remaining_size > 0) {
packet.clear();
if (remaining_size < payload_length) {
payload_length = remaining_size;
}
remaining_size -= payload_length;
BuildCommonRTPheader(&packet, remaining_size == 0, timestamp);
// Build Cast header.
packet.push_back(
(is_key ? kCastKeyFrameBitMask : 0) | kCastReferenceFrameIdBitMask);
packet.push_back(frame_id_);
int start_size = packet.size();
packet.resize(start_size + 32);
net::BigEndianWriter big_endian_writer(&((packet)[start_size]), 32);
big_endian_writer.WriteU16(packet_id_);
big_endian_writer.WriteU16(num_packets - 1);
packet.push_back(reference_frame_id);
// Copy payload data.
packet.insert(packet.end(), data_ptr, data_ptr + payload_length);
// Store packet.
packet_storage_->StorePacket(frame_id_, packet_id_, packet);
// Send to network.
transport_->SendPacket(packet, num_packets);
++packet_id_;
data_ptr += payload_length;
// Update stats.
++send_packets_count_;
send_octet_count_ += payload_length;
}
DCHECK(packet_id_ == num_packets) << "Invalid state";
// Prepare for next frame.
packet_id_ = 0;
frame_id_ = static_cast<uint8>(frame_id_ + 1);
}
void RtpPacketizer::BuildCommonRTPheader(
std::vector<uint8>* packet, bool marker_bit, uint32 time_stamp) {
packet->push_back(0x80);
packet->push_back(static_cast<uint8>(config_.payload_type) |
(marker_bit ? kRtpMarkerBitMask : 0));
int start_size = packet->size();
packet->resize(start_size + 80);
net::BigEndianWriter big_endian_writer(&((*packet)[start_size]), 80);
big_endian_writer.WriteU16(sequence_number_);
big_endian_writer.WriteU32(time_stamp);
big_endian_writer.WriteU32(config_.ssrc);
++sequence_number_;
}
} // namespace cast
} // namespace media
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