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* Copyright (c) 2012 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 <map>
#include <memory>
#include <vector>
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
#include "api/array_view.h"
#include "api/frame_transformer_interface.h"
#include "api/scoped_refptr.h"
#include "api/sequence_checker.h"
#include "api/task_queue/task_queue_base.h"
#include "api/task_queue/task_queue_factory.h"
#include "api/transport/rtp/dependency_descriptor.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "api/video/video_codec_type.h"
#include "api/video/video_frame_type.h"
#include "api/video/video_layers_allocation.h"
#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
#include "modules/rtp_rtcp/source/absolute_capture_time_sender.h"
#include "modules/rtp_rtcp/source/active_decode_targets_helper.h"
#include "modules/rtp_rtcp/source/rtp_rtcp_config.h"
#include "modules/rtp_rtcp/source/rtp_sender.h"
#include "modules/rtp_rtcp/source/rtp_sender_video_frame_transformer_delegate.h"
#include "modules/rtp_rtcp/source/rtp_video_header.h"
#include "modules/rtp_rtcp/source/video_fec_generator.h"
#include "rtc_base/bitrate_tracker.h"
#include "rtc_base/frequency_tracker.h"
#include "rtc_base/one_time_event.h"
#include "rtc_base/race_checker.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
class FrameEncryptorInterface;
class RtpPacketizer;
class RtpPacketToSend;
// kConditionallyRetransmitHigherLayers allows retransmission of video frames
// in higher layers if either the last frame in that layer was too far back in
// time, or if we estimate that a new frame will be available in a lower layer
// in a shorter time than it would take to request and receive a retransmission.
enum RetransmissionMode : uint8_t {
kRetransmitOff = 0x0,
kRetransmitBaseLayer = 0x2,
kRetransmitHigherLayers = 0x4,
kRetransmitAllLayers = 0x6,
kConditionallyRetransmitHigherLayers = 0x8
class RTPSenderVideo : public RTPVideoFrameSenderInterface {
static constexpr TimeDelta kTLRateWindowSize = TimeDelta::Millis(2'500);
struct Config {
Config() = default;
Config(const Config&) = delete;
Config(Config&&) = default;
// All members of this struct, with the exception of `field_trials`, are
// expected to outlive the RTPSenderVideo object they are passed to.
Clock* clock = nullptr;
RTPSender* rtp_sender = nullptr;
// Some FEC data is duplicated here in preparation of moving FEC to
// the egress stage.
absl::optional<VideoFecGenerator::FecType> fec_type;
size_t fec_overhead_bytes = 0; // Per packet max FEC overhead.
FrameEncryptorInterface* frame_encryptor = nullptr;
bool require_frame_encryption = false;
bool enable_retransmit_all_layers = false;
absl::optional<int> red_payload_type;
const FieldTrialsView* field_trials = nullptr;
rtc::scoped_refptr<FrameTransformerInterface> frame_transformer;
TaskQueueFactory* task_queue_factory = nullptr;
explicit RTPSenderVideo(const Config& config);
virtual ~RTPSenderVideo();
// `capture_time` and `clock::CurrentTime` should be using the same epoch.
// `expected_retransmission_time.IsFinite()` -> retransmission allowed.
// `encoder_output_size` is the size of the video frame as it came out of the
// video encoder, excluding any additional overhead.
// Calls to this method are assumed to be externally serialized.
bool SendVideo(int payload_type,
absl::optional<VideoCodecType> codec_type,
uint32_t rtp_timestamp,
Timestamp capture_time,
rtc::ArrayView<const uint8_t> payload,
size_t encoder_output_size,
RTPVideoHeader video_header,
TimeDelta expected_retransmission_time,
std::vector<uint32_t> csrcs) override;
bool SendEncodedImage(int payload_type,
absl::optional<VideoCodecType> codec_type,
uint32_t rtp_timestamp,
const EncodedImage& encoded_image,
RTPVideoHeader video_header,
TimeDelta expected_retransmission_time);
// Configures video structures produced by encoder to send using the
// dependency descriptor rtp header extension. Next call to SendVideo should
// have video_header.frame_type == kVideoFrameKey.
// All calls to SendVideo after this call must use video_header compatible
// with the video_structure.
void SetVideoStructure(const FrameDependencyStructure* video_structure);
// Should only be used by a RTPSenderVideoFrameTransformerDelegate and exists
// to ensure correct syncronization.
void SetVideoStructureAfterTransformation(
const FrameDependencyStructure* video_structure) override;
// Sets current active VideoLayersAllocation. The allocation will be sent
// using the rtp video layers allocation extension. The allocation will be
// sent in full on every key frame. The allocation will be sent once on a
// none discardable delta frame per call to this method and will not contain
// resolution and frame rate.
void SetVideoLayersAllocation(VideoLayersAllocation allocation);
// Should only be used by a RTPSenderVideoFrameTransformerDelegate and exists
// to ensure correct syncronization.
void SetVideoLayersAllocationAfterTransformation(
VideoLayersAllocation allocation) override;
// Returns the current post encode overhead rate, in bps. Note that this is
// the payload overhead, eg the VP8 payload headers and any other added
// metadata added by transforms. It does not include the RTP headers or
// extensions.
// TODO(sprang): Consider moving this to RtpSenderEgress so it's in the same
// place as the other rate stats.
DataRate PostEncodeOverhead() const;
// 'retransmission_mode' is either a value of enum RetransmissionMode, or
// computed with bitwise operators on values of enum RetransmissionMode.
void SetRetransmissionSetting(int32_t retransmission_settings);
static uint8_t GetTemporalId(const RTPVideoHeader& header);
bool AllowRetransmission(uint8_t temporal_id,
int32_t retransmission_settings,
TimeDelta expected_retransmission_time);
struct TemporalLayerStats {
FrequencyTracker frame_rate{kTLRateWindowSize};
Timestamp last_frame_time = Timestamp::Zero();
enum class SendVideoLayersAllocation {
void SetVideoStructureInternal(
const FrameDependencyStructure* video_structure);
void SetVideoLayersAllocationInternal(VideoLayersAllocation allocation);
void AddRtpHeaderExtensions(const RTPVideoHeader& video_header,
bool first_packet,
bool last_packet,
RtpPacketToSend* packet) const
size_t FecPacketOverhead() const RTC_EXCLUSIVE_LOCKS_REQUIRED(send_checker_);
void LogAndSendToNetwork(
std::vector<std::unique_ptr<RtpPacketToSend>> packets,
size_t encoder_output_size);
bool red_enabled() const { return red_payload_type_.has_value(); }
bool UpdateConditionalRetransmit(uint8_t temporal_id,
TimeDelta expected_retransmission_time)
void MaybeUpdateCurrentPlayoutDelay(const RTPVideoHeader& header)
RTPSender* const rtp_sender_;
Clock* const clock_;
// These members should only be accessed from within SendVideo() to avoid
// potential race conditions.
rtc::RaceChecker send_checker_;
int32_t retransmission_settings_ RTC_GUARDED_BY(send_checker_);
VideoRotation last_rotation_ RTC_GUARDED_BY(send_checker_);
absl::optional<ColorSpace> last_color_space_ RTC_GUARDED_BY(send_checker_);
bool transmit_color_space_next_frame_ RTC_GUARDED_BY(send_checker_);
std::unique_ptr<FrameDependencyStructure> video_structure_
absl::optional<VideoLayersAllocation> allocation_
// Flag indicating if we should send `allocation_`.
SendVideoLayersAllocation send_allocation_ RTC_GUARDED_BY(send_checker_);
absl::optional<VideoLayersAllocation> last_full_sent_allocation_
// Current target playout delay.
absl::optional<VideoPlayoutDelay> current_playout_delay_
// Flag indicating if we need to send `current_playout_delay_` in order
// to guarantee it gets delivered.
bool playout_delay_pending_;
// Set by the field trial WebRTC-ForceSendPlayoutDelay to override the playout
// delay of outgoing video frames.
const absl::optional<VideoPlayoutDelay> forced_playout_delay_;
// Should never be held when calling out of this class.
Mutex mutex_;
const absl::optional<int> red_payload_type_;
absl::optional<VideoFecGenerator::FecType> fec_type_;
const size_t fec_overhead_bytes_; // Per packet max FEC overhead.
mutable Mutex stats_mutex_;
BitrateTracker post_encode_overhead_bitrate_ RTC_GUARDED_BY(stats_mutex_);
std::map<int, TemporalLayerStats> frame_stats_by_temporal_layer_
OneTimeEvent first_frame_sent_;
// E2EE Custom Video Frame Encryptor (optional)
FrameEncryptorInterface* const frame_encryptor_ = nullptr;
// If set to true will require all outgoing frames to pass through an
// initialized frame_encryptor_ before being sent out of the network.
// Otherwise these payloads will be dropped.
const bool require_frame_encryption_;
// Set to true if the generic descriptor should be authenticated.
const bool generic_descriptor_auth_experiment_;
AbsoluteCaptureTimeSender absolute_capture_time_sender_
// Tracks updates to the active decode targets and decides when active decode
// targets bitmask should be attached to the dependency descriptor.
ActiveDecodeTargetsHelper active_decode_targets_tracker_;
const rtc::scoped_refptr<RTPSenderVideoFrameTransformerDelegate>
} // namespace webrtc