webrtc_m130/video/g3doc/stats.md

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.

• frames_encoded - total number of encoded frames.
• encode_frame_rate - number of encoded frames during the last second.
• width - width of last encoded frame [rtcoutboundrtpstreamstats-framewidth].
• height - height of last encoded frame [rtcoutboundrtpstreamstats-frameheight].
• total_encode_time_ms - total encode time for encoded frames.
• qp_sum - sum of quantizer values of encoded frames [rtcoutboundrtpstreamstats-qpsum].
• frame_counts - total number of encoded key/delta frames [rtcoutboundrtpstreamstats-keyframesencoded].

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.

• encoder_implementation_name - name of encoder implementation [rtcoutboundrtpstreamstats-encoderimplementation].

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

• frames_encoded - total number of encoded frames [rtcoutboundrtpstreamstats-framesencoded].
• encode_frame_rate - number of encoded frames during the last second [rtcoutboundrtpstreamstats-framespersecond].
• total_encoded_bytes_target - total target frame size in bytes [rtcoutboundrtpstreamstats-totalencodedbytestarget].
• huge_frames_sent - total number of huge frames sent [rtcoutboundrtpstreamstats-hugeframessent].
• media_bitrate_bps - the actual bitrate the encoder is producing.
• avg_encode_time_ms - average encode time for encoded frames.
• total_encode_time_ms - total encode time for encoded frames [rtcoutboundrtpstreamstats-totalencodetime].
• frames_dropped_by_encoder- total number of dropped frames by the encoder.

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 VideoStreamBufferControllerStatsObserver, 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.

• frame_counts - total number of key/delta frames received [rtcinboundrtpstreamstats-keyframesdecoded].
• network_frame_rate - number of frames received during the last second.

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

• jitter_buffer_ms - jitter delay in ms: this is the delay added to handle network jitter
• 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: this is the time spent waiting in the jitter buffer [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.

• decoder_implementation_name - name of decoder implementation [rtcinboundrtpstreamstats-decoderimplementation].

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.

• frames_decoded - total number of decoded frames [rtcinboundrtpstreamstats-framesdecoded].
• decode_frame_rate - number of decoded frames during the last second [rtcinboundrtpstreamstats-framespersecond].
• decode_ms - time to decode last frame in ms.
• total_decode_time_ms - total decode time for decoded frames [rtcinboundrtpstreamstats-totaldecodetime].
• qp_sum - sum of quantizer values of decoded frames [rtcinboundrtpstreamstats-qpsum].
• content_type - content type (UNSPECIFIED/SCREENSHARE).
• interframe_delay_max_ms - max inter-frame delay within a time window between decoded frames.

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_inter_frame_delay - sum of inter-frame delay in seconds between rendered frames [rtcinboundrtpstreamstats-totalinterframedelay].
• total_squared_inter_frame_delay - sum of squared inter-frame delays in seconds between rendered frames [rtcinboundrtpstreamstats-totalsquaredinterframedelay].

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].