Video stats

Overview of collected statistics for VideoSendStream and VideoReceiveStream.

VideoSendStream

VideoSendStream::Stats for a sending stream can be gathered via VideoSendStream::GetStats().

Some statistics are collected per RTP stream (see StreamStats) and can be of StreamType: kMedia, kRtx, kFlexfec.

Multiple StreamStats objects are for example present if simulcast is used (multiple kMedia objects) or if RTX or FlexFEC is negotiated.

SendStatisticsProxy

VideoSendStream owns a SendStatisticsProxy which implements VideoStreamEncoderObserver, RtcpStatisticsCallback, ReportBlockDataObserver, RtcpPacketTypeCounterObserver, StreamDataCountersCallback, BitrateStatisticsObserver, FrameCountObserver, SendSideDelayObserver and holds a VideoSendStream::Stats object.

SendStatisticsProxy is called via these interfaces by different components (e.g. RtpRtcp module) to update stats.

StreamStats

  • type - kMedia, kRtx or kFlexfec.
  • referenced_media_ssrc - only present for type kRtx/kFlexfec. The SSRC for the kMedia stream that retransmissions or FEC is performed for.

Updated when a frame has been encoded, VideoStreamEncoder::OnEncodedImage.

Updated when a RTP packet is transmitted to the network, RtpSenderEgress::SendPacket.

  • rtp_stats - total number of sent bytes/packets.
  • total_bitrate_bps - total bitrate sent in bits per second (over a one second window).
  • retransmit_bitrate_bps - total retransmit bitrate sent in bits per second (over a one second window).
  • avg_delay_ms - average capture-to-send delay for sent packets (over a one second window).
  • max_delay_ms - maximum capture-to-send delay for sent packets (over a one second window).
  • total_packet_send_delay_ms - total capture-to-send delay for sent packets [rtcoutboundrtpstreamstats-totalpacketsenddelay].

Updated when an incoming RTCP packet is parsed, RTCPReceiver::ParseCompoundPacket.

  • rtcp_packet_type_counts - total number of received NACK/FIR/PLI packets [rtcoutboundrtpstreamstats-nackcount, fircount, plicount].

Updated when a RTCP report block packet is received, RTCPReceiver::TriggerCallbacksFromRtcpPacket.

  • rtcp_stats - RTCP report block data.
  • report_block_data - RTCP report block data.

Stats

  • std::map<uint32_t, StreamStats> substreams - StreamStats mapped per SSRC.

Updated when a frame is received from the source, VideoStreamEncoder::OnFrame.

  • frames - total number of frames fed to VideoStreamEncoder.
  • input_frame_rate - number of frames fed to VideoStreamEncoder during the last second.
  • frames_dropped_by_congestion_window - total number of dropped frames due to congestion window pushback.
  • frames_dropped_by_encoder_queue - total number of dropped frames due to that the encoder is blocked.

Updated if a frame from the source is dropped, VideoStreamEncoder::OnDiscardedFrame.

  • frames_dropped_by_capturer - total number dropped frames by the source.

Updated if a frame is dropped by FrameDropper, VideoStreamEncoder::MaybeEncodeVideoFrame.

  • frames_dropped_by_rate_limiter - total number of dropped frames to avoid bitrate overuse.

Updated (if changed) before a frame is passed to the encoder, VideoStreamEncoder::EncodeVideoFrame.

Updated after a frame has been encoded, VideoStreamEncoder::OnEncodedImage.

Adaptation stats.

  • bw_limited_resolution - shows if resolution is limited due to restricted bandwidth.
  • cpu_limited_resolution - shows if resolution is limited due to cpu.
  • bw_limited_framerate - shows if framerate is limited due to restricted bandwidth.
  • cpu_limited_framerate - shows if framerate is limited due to cpu.
  • quality_limitation_reason - current reason for limiting resolution and/or framerate [rtcoutboundrtpstreamstats-qualitylimitationreason].
  • quality_limitation_durations_ms - total time spent in quality limitation state [rtcoutboundrtpstreamstats-qualitylimitationdurations].
  • quality_limitation_resolution_changes - total number of times that resolution has changed due to quality limitation [rtcoutboundrtpstreamstats-qualitylimitationresolutionchanges].
  • number_of_cpu_adapt_changes - total number of times resolution/framerate has changed due to cpu limitation.
  • number_of_quality_adapt_changes - total number of times resolution/framerate has changed due to quality limitation.

Updated when the encoder is configured, VideoStreamEncoder::ReconfigureEncoder.

  • content_type - configured content type (UNSPECIFIED/SCREENSHARE).

Updated when the available bitrate changes, VideoSendStreamImpl::OnBitrateUpdated.

  • target_media_bitrate_bps - the bitrate the encoder is configured to use.
  • suspended - shows if video is suspended due to zero target bitrate.

VideoReceiveStream

VideoReceiveStream::Stats for a receiving stream can be gathered via VideoReceiveStream::GetStats().

ReceiveStatisticsProxy

VideoReceiveStream owns a ReceiveStatisticsProxy which implements VCMReceiveStatisticsCallback, RtcpCnameCallback, RtcpPacketTypeCounterObserver, CallStatsObserver and holds a VideoReceiveStream::Stats object.

ReceiveStatisticsProxy is called via these interfaces by different components (e.g. RtpRtcp module) to update stats.

Stats

  • current_payload_type - current payload type.
  • ssrc - configured SSRC for the received stream.

Updated when a complete frame is received, FrameBuffer::InsertFrame.

Updated when a frame is ready for decoding, FrameBuffer::GetNextFrame. From VCMTiming:

  • jitter_buffer_ms - jitter buffer delay in ms.
  • max_decode_ms - the 95th percentile observed decode time within a time window (10 sec).
  • render_delay_ms - render delay in ms.
  • min_playout_delay_ms - minimum playout delay in ms.
  • target_delay_ms - target playout delay in ms. Max(min_playout_delay_ms, jitter_delay_ms + max_decode_ms + render_delay_ms).
  • current_delay_ms - actual playout delay in ms.
  • jitter_buffer_delay_seconds - total jitter buffer delay in seconds [rtcinboundrtpstreamstats-jitterbufferdelay].
  • jitter_buffer_emitted_count - total number of frames that have come out from the jitter buffer [rtcinboundrtpstreamstats-jitterbufferemittedcount].

Updated (if changed) after a frame is passed to the decoder, VCMGenericDecoder::Decode.

Updated when a frame is ready for decoding, FrameBuffer::GetNextFrame.

  • timing_frame_info - timestamps for a full lifetime of a frame.
  • first_frame_received_to_decoded_ms - initial decoding latency between the first arrived frame and the first decoded frame.
  • frames_dropped - total number of dropped frames prior to decoding or if the system is too slow [rtcreceivedrtpstreamstats-framesdropped].

Updated after a frame has been decoded, VCMDecodedFrameCallback::Decoded.

Updated before a frame is sent to the renderer, VideoReceiveStream2::OnFrame.

  • frames_rendered - total number of rendered frames.
  • render_frame_rate - number of rendered frames during the last second.
  • width - width of last frame fed to renderer [rtcinboundrtpstreamstats-framewidth].
  • height - height of last frame fed to renderer [rtcinboundrtpstreamstats-frameheight].
  • estimated_playout_ntp_timestamp_ms - estimated playout NTP timestamp [rtcinboundrtpstreamstats-estimatedplayouttimestamp].
  • sync_offset_ms - NTP timestamp difference between the last played out audio and video frame.
  • freeze_count - total number of detected freezes.
  • pause_count - total number of detected pauses.
  • total_freezes_duration_ms - total duration of freezes in ms.
  • total_pauses_duration_ms - total duration of pauses in ms.
  • total_frames_duration_ms - time in ms between the last rendered frame and the first rendered frame.
  • sum_squared_frame_durations - sum of squared inter-frame delays in seconds between rendered frames.

ReceiveStatisticsImpl::OnRtpPacket is updated for received RTP packets. From ReceiveStatistics:

  • total_bitrate_bps - incoming bitrate in bps.
  • rtp_stats - RTP statistics for the received stream.

Updated when a RTCP packet is sent, RTCPSender::ComputeCompoundRTCPPacket.

  • rtcp_packet_type_counts - total number of sent NACK/FIR/PLI packets [rtcinboundrtpstreamstats-nackcount, fircount, plicount].