chromium/third_party/webrtc/modules/rtp_rtcp/source/rtcp_packet/target_bitrate.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/rtcp_packet/target_bitrate.h"

#include "modules/rtp_rtcp/source/byte_io.h"
#include "rtc_base/checks.h"
#include "rtc_base/numerics/safe_conversions.h"

namespace webrtc {
namespace rtcp {
constexpr size_t kTargetBitrateHeaderSizeBytes = …;
constexpr uint8_t TargetBitrate::kBlockType;
const size_t TargetBitrate::kBitrateItemSizeBytes = …;

TargetBitrate::BitrateItem::BitrateItem()
    : … { … }

TargetBitrate::BitrateItem::BitrateItem(uint8_t spatial_layer,
                                        uint8_t temporal_layer,
                                        uint32_t target_bitrate_kbps)
    : … { … }

//  RFC 4585: Feedback format.
//
//  Common packet format:
//
//   0                   1                   2                   3
//   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |     BT=42     |   reserved    |         block length          |
//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//
//  Target bitrate item (repeat as many times as necessary).
//
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  |   S   |   T   |                Target Bitrate                 |
//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  :  ...                                                          :
//
//  Spatial Layer (S): 4 bits
//    Indicates which temporal layer this bitrate concerns.
//
//  Temporal Layer (T): 4 bits
//    Indicates which temporal layer this bitrate concerns.
//
//  Target Bitrate: 24 bits
//    The encoder target bitrate for this layer, in kbps.
//
//  As an example of how S and T are intended to be used, VP8 simulcast will
//  use a separate TargetBitrate message per stream, since they are transmitted
//  on separate SSRCs, with temporal layers grouped by stream.
//  If VP9 SVC is used, there will be only one SSRC, so each spatial and
//  temporal layer combo used shall be specified in the TargetBitrate packet.

TargetBitrate::TargetBitrate() = default;
TargetBitrate::TargetBitrate(const TargetBitrate&) = default;
TargetBitrate& TargetBitrate::operator=(const TargetBitrate&) = default;
TargetBitrate::~TargetBitrate() = default;

void TargetBitrate::Parse(const uint8_t* block, uint16_t block_length) { … }

void TargetBitrate::AddTargetBitrate(uint8_t spatial_layer,
                                     uint8_t temporal_layer,
                                     uint32_t target_bitrate_kbps) { … }

const std::vector<TargetBitrate::BitrateItem>&
TargetBitrate::GetTargetBitrates() const { … }

size_t TargetBitrate::BlockLength() const { … }

void TargetBitrate::Create(uint8_t* buffer) const { … }

}  // namespace rtcp
}  // namespace webrtc