blob: f4778415c01b69a76ef07812a8428ac4c262177a [file] [log] [blame]
// Copyright 2014 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/net/rtp/rtp_packetizer.h"
#include <string>
#include "base/big_endian.h"
#include "base/check_op.h"
#include "media/cast/net/pacing/paced_sender.h"
#include "media/cast/net/rtp/rtp_defines.h"
namespace media {
namespace cast {
RtpPacketizerConfig::RtpPacketizerConfig()
: payload_type(-1),
max_payload_length(kMaxIpPacketSize - 28), // Default is IP-v4/UDP.
sequence_number(0),
ssrc(0) {}
RtpPacketizerConfig::~RtpPacketizerConfig() = default;
RtpPacketizer::RtpPacketizer(PacedSender* const transport,
PacketStorage* packet_storage,
RtpPacketizerConfig rtp_packetizer_config)
: config_(rtp_packetizer_config),
transport_(transport),
packet_storage_(packet_storage),
sequence_number_(config_.sequence_number),
send_packet_count_(0),
send_octet_count_(0) {
DCHECK(transport) << "Invalid argument";
}
RtpPacketizer::~RtpPacketizer() = default;
uint16_t RtpPacketizer::NextSequenceNumber() {
++sequence_number_;
return sequence_number_ - 1;
}
void RtpPacketizer::SendFrameAsPackets(const EncodedFrame& frame) {
uint16_t rtp_header_length = kRtpHeaderLength + kCastHeaderLength;
uint16_t max_length = config_.max_payload_length - rtp_header_length - 1;
// Split the payload evenly (round number up).
size_t num_packets = (frame.data.size() + max_length) / max_length;
size_t payload_length = (frame.data.size() + num_packets) / num_packets;
DCHECK_LE(payload_length, max_length) << "Invalid argument";
SendPacketVector packets;
size_t remaining_size = frame.data.size();
std::string::const_iterator data_iter = frame.data.begin();
uint8_t num_extensions = 0;
if (frame.new_playout_delay_ms)
num_extensions++;
DCHECK_LE(num_extensions, kCastExtensionCountmask);
while (remaining_size > 0) {
PacketRef packet(new base::RefCountedData<Packet>);
if (remaining_size < payload_length) {
payload_length = remaining_size;
}
remaining_size -= payload_length;
BuildCommonRTPheader(
&packet->data, remaining_size == 0, frame.rtp_timestamp);
// Build Cast header.
// TODO(miu): Should we always set the ref frame bit and the ref_frame_id?
DCHECK_NE(frame.dependency, EncodedFrame::UNKNOWN_DEPENDENCY);
uint8_t byte0 = kCastReferenceFrameIdBitMask;
if (frame.dependency == EncodedFrame::KEY)
byte0 |= kCastKeyFrameBitMask;
// Extensions only go on the first packet of the frame
const uint16_t packet_id = static_cast<uint16_t>(packets.size());
if (packet_id == 0)
byte0 |= num_extensions;
packet->data.push_back(byte0);
packet->data.push_back(frame.frame_id.lower_8_bits());
size_t start_size = packet->data.size();
packet->data.resize(start_size + 4);
base::BigEndianWriter big_endian_writer(
reinterpret_cast<char*>(&(packet->data[start_size])), 4);
big_endian_writer.WriteU16(packet_id);
big_endian_writer.WriteU16(static_cast<uint16_t>(num_packets - 1));
packet->data.push_back(frame.referenced_frame_id.lower_8_bits());
// Add extension details only on the first packet of the frame
if (packet_id == 0 && frame.new_playout_delay_ms) {
packet->data.push_back(kCastRtpExtensionAdaptiveLatency << 2);
packet->data.push_back(2); // 2 bytes
packet->data.push_back(
static_cast<uint8_t>(frame.new_playout_delay_ms >> 8));
packet->data.push_back(static_cast<uint8_t>(frame.new_playout_delay_ms));
}
// Copy payload data.
packet->data.insert(packet->data.end(),
data_iter,
data_iter + payload_length);
data_iter += payload_length;
packets.push_back(make_pair(PacketKey(frame.reference_time, config_.ssrc,
frame.frame_id, packet_id),
packet));
// Update stats.
++send_packet_count_;
send_octet_count_ += payload_length;
}
DCHECK_EQ(num_packets, packets.size()) << "Invalid state";
packet_storage_->StoreFrame(frame.frame_id, packets);
// Send to network.
transport_->SendPackets(packets);
}
void RtpPacketizer::BuildCommonRTPheader(Packet* packet,
bool marker_bit,
RtpTimeTicks rtp_timestamp) {
packet->push_back(0x80);
packet->push_back(static_cast<uint8_t>(config_.payload_type) |
(marker_bit ? kRtpMarkerBitMask : 0));
size_t start_size = packet->size();
packet->resize(start_size + 10);
base::BigEndianWriter big_endian_writer(
reinterpret_cast<char*>(&((*packet)[start_size])), 10);
big_endian_writer.WriteU16(sequence_number_);
big_endian_writer.WriteU32(rtp_timestamp.lower_32_bits());
big_endian_writer.WriteU32(config_.ssrc);
++sequence_number_;
}
} // namespace cast
} // namespace media