| // 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. |
| // |
| // This is the base class for an object that send frames to a receiver. |
| // TODO(hclam): Refactor such that there is no separate AudioSender vs. |
| // VideoSender, and the functionality of both is rolled into this class. |
| |
| #ifndef COBALT_MEDIA_CAST_SENDER_FRAME_SENDER_H_ |
| #define COBALT_MEDIA_CAST_SENDER_FRAME_SENDER_H_ |
| |
| #include "base/macros.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/memory/weak_ptr.h" |
| #include "base/time/time.h" |
| #include "media/cast/cast_config.h" |
| #include "media/cast/cast_environment.h" |
| #include "media/cast/net/cast_transport.h" |
| #include "media/cast/net/rtcp/rtcp_defines.h" |
| #include "media/cast/sender/congestion_control.h" |
| #include "starboard/types.h" |
| |
| namespace cobalt { |
| namespace media { |
| namespace cast { |
| |
| struct SenderEncodedFrame; |
| |
| class FrameSender { |
| public: |
| FrameSender(scoped_refptr<CastEnvironment> cast_environment, |
| CastTransport* const transport_sender, |
| const FrameSenderConfig& config, |
| CongestionControl* congestion_control); |
| virtual ~FrameSender(); |
| |
| int rtp_timebase() const { return rtp_timebase_; } |
| |
| // Calling this function is only valid if the receiver supports the |
| // "extra_playout_delay", rtp extension. |
| void SetTargetPlayoutDelay(base::TimeDelta new_target_playout_delay); |
| |
| base::TimeDelta GetTargetPlayoutDelay() const { |
| return target_playout_delay_; |
| } |
| |
| // Called by the encoder with the next EncodeFrame to send. |
| void SendEncodedFrame(int requested_bitrate_before_encode, |
| std::unique_ptr<SenderEncodedFrame> encoded_frame); |
| |
| protected: |
| // Returns the number of frames in the encoder's backlog. |
| virtual int GetNumberOfFramesInEncoder() const = 0; |
| |
| // Returns the duration of the data in the encoder's backlog plus the duration |
| // of sent, unacknowledged frames. |
| virtual base::TimeDelta GetInFlightMediaDuration() const = 0; |
| |
| protected: |
| class RtcpClient : public RtcpObserver { |
| public: |
| explicit RtcpClient(base::WeakPtr<FrameSender> frame_sender); |
| ~RtcpClient() override; |
| |
| void OnReceivedCastMessage(const RtcpCastMessage& cast_message) override; |
| void OnReceivedRtt(base::TimeDelta round_trip_time) override; |
| void OnReceivedPli() override; |
| |
| private: |
| const base::WeakPtr<FrameSender> frame_sender_; |
| }; |
| // Schedule and execute periodic sending of RTCP report. |
| void ScheduleNextRtcpReport(); |
| void SendRtcpReport(bool schedule_future_reports); |
| |
| // Protected for testability. |
| void OnReceivedCastFeedback(const RtcpCastMessage& cast_feedback); |
| |
| // Called when a Pli message is received. |
| void OnReceivedPli(); |
| |
| void OnMeasuredRoundTripTime(base::TimeDelta rtt); |
| |
| const scoped_refptr<CastEnvironment> cast_environment_; |
| |
| // Sends encoded frames over the configured transport (e.g., UDP). In |
| // Chromium, this could be a proxy that first sends the frames from a renderer |
| // process to the browser process over IPC, with the browser process being |
| // responsible for "packetizing" the frames and pushing packets into the |
| // network layer. |
| CastTransport* const transport_sender_; |
| |
| const uint32_t ssrc_; |
| |
| protected: |
| // Schedule and execute periodic checks for re-sending packets. If no |
| // acknowledgements have been received for "too long," AudioSender will |
| // speculatively re-send certain packets of an unacked frame to kick-start |
| // re-transmission. This is a last resort tactic to prevent the session from |
| // getting stuck after a long outage. |
| void ScheduleNextResendCheck(); |
| void ResendCheck(); |
| void ResendForKickstart(); |
| |
| // Returns true if too many frames would be in-flight by encoding and sending |
| // the next frame having the given |frame_duration|. |
| bool ShouldDropNextFrame(base::TimeDelta frame_duration) const; |
| |
| // Record or retrieve a recent history of each frame's timestamps. |
| // Warning: If a frame ID too far in the past is requested, the getters will |
| // silently succeed but return incorrect values. Be sure to respect |
| // media::cast::kMaxUnackedFrames. |
| void RecordLatestFrameTimestamps(FrameId frame_id, |
| base::TimeTicks reference_time, |
| RtpTimeTicks rtp_timestamp); |
| base::TimeTicks GetRecordedReferenceTime(FrameId frame_id) const; |
| RtpTimeTicks GetRecordedRtpTimestamp(FrameId frame_id) const; |
| |
| // Returns the number of frames that were sent but not yet acknowledged. |
| int GetUnacknowledgedFrameCount() const; |
| |
| // Playout delay represents total amount of time between a frame's |
| // capture/recording on the sender and its playback on the receiver |
| // (i.e., shown to a user). This should be a value large enough to |
| // give the system sufficient time to encode, transmit/retransmit, |
| // receive, decode, and render; given its run-time environment |
| // (sender/receiver hardware performance, network conditions,etc.). |
| |
| // The |target_playout delay_| is the current delay that is adaptively |
| // adjusted based on feedback from video capture engine and the congestion |
| // control. In case of interactive content, the target is adjusted to start |
| // at |min_playout_delay_| and in case of animated content, it starts out at |
| // |animated_playout_delay_| and then adaptively adjust based on feedback |
| // from congestion control. |
| base::TimeDelta target_playout_delay_; |
| const base::TimeDelta min_playout_delay_; |
| const base::TimeDelta max_playout_delay_; |
| // Starting playout delay for animated content. |
| const base::TimeDelta animated_playout_delay_; |
| |
| // If true, we transmit the target playout delay to the receiver. |
| bool send_target_playout_delay_; |
| |
| // Max encoded frames generated per second. |
| double max_frame_rate_; |
| |
| // Counts how many RTCP reports are being "aggressively" sent (i.e., one per |
| // frame) at the start of the session. Once a threshold is reached, RTCP |
| // reports are instead sent at the configured interval + random drift. |
| int num_aggressive_rtcp_reports_sent_; |
| |
| // This is "null" until the first frame is sent. Thereafter, this tracks the |
| // last time any frame was sent or re-sent. |
| base::TimeTicks last_send_time_; |
| |
| // The ID of the last frame sent. This member is invalid until |
| // |!last_send_time_.is_null()|. |
| FrameId last_sent_frame_id_; |
| |
| // The ID of the latest (not necessarily the last) frame that has been |
| // acknowledged. This member is invalid until |!last_send_time_.is_null()|. |
| FrameId latest_acked_frame_id_; |
| |
| // Counts the number of duplicate ACK that are being received. When this |
| // number reaches a threshold, the sender will take this as a sign that the |
| // receiver hasn't yet received the first packet of the next frame. In this |
| // case, VideoSender will trigger a re-send of the next frame. |
| int duplicate_ack_counter_; |
| |
| // This object controls how we change the bitrate to make sure the |
| // buffer doesn't overflow. |
| std::unique_ptr<CongestionControl> congestion_control_; |
| |
| // The most recently measured round trip time. |
| base::TimeDelta current_round_trip_time_; |
| |
| // This flag is set true when a Pli message is received. It is cleared once |
| // the FrameSender scheduled an encoded key frame to be sent. |
| bool picture_lost_at_receiver_; |
| |
| private: |
| // Returns the maximum media duration currently allowed in-flight. This |
| // fluctuates in response to the currently-measured network latency. |
| base::TimeDelta GetAllowedInFlightMediaDuration() const; |
| |
| // RTP timestamp increment representing one second. |
| const int rtp_timebase_; |
| |
| const bool is_audio_; |
| |
| // Ring buffers to keep track of recent frame timestamps (both in terms of |
| // local reference time and RTP media time). These should only be accessed |
| // through the Record/GetXXX() methods. The index into this ring |
| // buffer is the lower 8 bits of the FrameId. |
| base::TimeTicks frame_reference_times_[256]; |
| RtpTimeTicks frame_rtp_timestamps_[256]; |
| |
| // NOTE: Weak pointers must be invalidated before all other member variables. |
| base::WeakPtrFactory<FrameSender> weak_factory_; |
| |
| DISALLOW_COPY_AND_ASSIGN(FrameSender); |
| }; |
| |
| } // namespace cast |
| } // namespace media |
| } // namespace cobalt |
| |
| #endif // COBALT_MEDIA_CAST_SENDER_FRAME_SENDER_H_ |