chromium/third_party/webrtc/modules/rtp_rtcp/source/ulpfec_header_reader_writer.cc

/*
 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "modules/rtp_rtcp/source/ulpfec_header_reader_writer.h"

#include <string.h>

#include "api/scoped_refptr.h"
#include "modules/rtp_rtcp/source/byte_io.h"
#include "modules/rtp_rtcp/source/forward_error_correction_internal.h"
#include "rtc_base/checks.h"

namespace webrtc {

namespace {

// Maximum number of media packets that can be protected in one batch.
constexpr size_t kMaxMediaPackets = …;

// Maximum number of media packets tracked by FEC decoder.
// Maintain a sufficiently larger tracking window than `kMaxMediaPackets`
// to account for packet reordering in pacer/ network.
constexpr size_t kMaxTrackedMediaPackets = …;

// Maximum number of FEC packets stored inside ForwardErrorCorrection.
constexpr size_t kMaxFecPackets = …;

// FEC Level 0 header size in bytes.
constexpr size_t kFecLevel0HeaderSize = …;

// FEC Level 1 (ULP) header size in bytes (L bit is set).
constexpr size_t kFecLevel1HeaderSizeLBitSet = …;

// FEC Level 1 (ULP) header size in bytes (L bit is cleared).
constexpr size_t kFecLevel1HeaderSizeLBitClear = …;

constexpr size_t kPacketMaskOffset = …;

size_t UlpfecHeaderSize(size_t packet_mask_size) { … }

}  // namespace

UlpfecHeaderReader::UlpfecHeaderReader()
    : … { … }

UlpfecHeaderReader::~UlpfecHeaderReader() = default;

bool UlpfecHeaderReader::ReadFecHeader(
    ForwardErrorCorrection::ReceivedFecPacket* fec_packet) const { … }

UlpfecHeaderWriter::UlpfecHeaderWriter()
    : … { … }

UlpfecHeaderWriter::~UlpfecHeaderWriter() = default;

// TODO(brandtr): Consider updating this implementation (which actually
// returns a bound on the sequence number spread), if logic is added to
// UlpfecHeaderWriter::FinalizeFecHeader to truncate packet masks which end
// in a string of zeroes. (Similar to how it is done in the FlexFEC case.)
size_t UlpfecHeaderWriter::MinPacketMaskSize(const uint8_t* packet_mask,
                                             size_t packet_mask_size) const { … }

size_t UlpfecHeaderWriter::FecHeaderSize(size_t packet_mask_size) const { … }

void UlpfecHeaderWriter::FinalizeFecHeader(
    rtc::ArrayView<const ProtectedStream> protected_streams,
    ForwardErrorCorrection::Packet& fec_packet) const { … }

}  // namespace webrtc