RTCInboundRtpStreamStats
The RTCInboundRtpStreamStats
dictionary of the WebRTC API is used to report statistics related to the receiving end of an RTP stream on the local end of the RTCPeerConnection
.
The statistics can be obtained by iterating the RTCStatsReport
returned by RTCPeerConnection.getStats()
or RTCRtpReceiver.getStats()
until you find a report with the type
of inbound-rtp
.
Instance properties
averageRtcpInterval
-
A floating-point value indicating the average RTCP interval between two consecutive compound RTCP packets.
bytesReceived
-
A 64-bit integer which indicates the total number of bytes that have been received so far for this media source.
fecPacketsDiscarded
-
An integer value indicating the number of RTP Forward Error Correction (FEC) packets which have been received for this source, for which the error correction payload was discarded.
fecPacketsReceived
-
An integer value indicating the total number of RTP FEC packets received for this source. This counter may also be incremented when FEC packets arrive in-band along with media content; this can happen with Opus, for example.
firCount
-
An integer value which indicates the total number of Full Intra Request (FIR) packets which this receiver has sent to the sender. This is an indicator of how often the stream has lagged, requiring frames to be skipped in order to catch up. This value is only available for video streams.
framesDecoded
-
A long integer value indicating the total number of frames of video which have been correctly decoded so far for this media source. This is the number of frames that would have been rendered if none were dropped. Only valid for video streams.
lastPacketReceivedTimestamp
-
A
DOMHighResTimeStamp
indicating the time at which the last packet was received for this source. Thetimestamp
property, on the other hand, indicates the time at which the statistics object was generated. nackCount
-
An integer value indicating the total number of Negative ACKnolwedgement (NACK) packets this receiver has sent.
packetsDuplicated
-
An integer value indicating the total number of packets that have been discarded because they were duplicates. These packets are not counted by
packetsDiscarded
. packetsFailedDecryption
-
An integer totaling the number of RTP packets that could not be decrypted. These packets are not counted by
packetsDiscarded
. perDscpPacketsReceived
-
A record of key-value pairs with strings as the keys mapped to 32-bit integer values, each indicating the total number of packets this receiver has received on this RTP stream from this source for each Differentiated Services Code Point (DSCP).
pliCount
-
An integer specifying the number of times the receiver has notified the sender that some amount of encoded video data for one or more frames has been lost, using Picture Loss Indication (PLI) packets. This is only available for video streams.
qpSum
-
A 64-bit value containing the sum of the QP values for every frame decoded by this RTP receiver. You can determine the average QP per frame by dividing this value by
framesDecoded
. Valid only for video streams. receiverId
-
A string indicating which identifies the
RTCAudioReceiverStats
orRTCVideoReceiverStats
object associated with the stream's receiver. This ID is stable across multiple calls togetStats()
. remoteId
-
A string which identifies the
RTCRemoteOutboundRtpStreamStats
object that provides statistics for the remote peer for this same SSRC. This ID is stable across multiple calls togetStats()
. sliCount
-
An integer indicating the number of times the receiver sent a Slice Loss Indication (SLI) frame to the sender to tell it that one or more consecutive (in terms of scan order) video macroblocks have been lost or corrupted. Available only for video streams.
trackIdentifier
-
A string that contains the
id
value of theMediaStreamTrack
associated with the inbound stream. trackId
Deprecated-
A string which identifies the statistics object representing the receiving track; this object is one of two types:
RTCReceiverAudioTrackAttachmentStats
orRTCReceiverVideoTrackAttachmentStats
. This ID is stable across multiple calls togetStats()
.
Statistics measured at the receiver of an RTP stream
These statistics are measured at the receiving end of an RTP stream, regardless of whether it's local or remote.
packetsReceived
-
The total number of RTP packets received for this synchronizing source, including retransmissions.
packetsLost
-
The total number of RTP packets lost for this synchronizing source. Note that this can be negative if more packets are received than sent.
jitter
-
Packet jitter for this synchronizing source, measured in seconds.
Standard fields included for all media types
codecId
-
A string which uniquely identifies the object which was inspected to produce the
RTCCodecStats
object associated with this RTP stream. kind
-
A string whose value is
"audio"
if the associatedMediaStreamTrack
is audio-only or"video"
if the track contains video. This value will match that of the media type indicated byRTCCodecStats.codec
, as well as the track'skind
property. Previously calledmediaType
. ssrc
-
The 32-bit integer which identifies the source of the RTP packets this
RTCRtpStreamStats
object covers. This value is generated per the RFC 3550 specification. trackId
-
A string which uniquely identifies the
RTCMediaStreamTrackStats
object representing the associatedMediaStreamTrack
. This is not the same as the value ofMediaStreamTrack.id
. transportId
-
A string uniquely identifying the object which was inspected to produce the
RTCTransportStats
object associated with this RTP stream.
Local-only measurements
These properties are computed locally, and are only available to the device receiving the media stream. Their primary purpose is to examine the error resiliency of the connection, as they provide information about lost packets, lost frames, and how heavily compressed the data is.
firCount
-
A count of the total number of Full Intra Request (FIR) packets received by the sender. This statistic is only available to the device which is receiving the stream and is only available for video tracks. A FIR packet is sent by the receiving end of the stream when it falls behind or has lost packets and is unable to continue decoding the stream; the sending end of the stream receives the FIR packet and responds by sending a full frame instead of a delta frame, thereby letting the receiver "catch up." The higher this number is, the more often a problem of this nature arose, which can be a sign of network congestion or an overburdened receiving device.
nackCount
-
The number of times the receiver notified the sender that one or more RTP packets has been lost by sending a Negative ACKnowledgement (NACK, also called "Generic NACK") packet to the sender. This value is only available to the receiver.
pliCount
-
The number of times the receiving end of the stream sent a Picture Loss Indication (PLI) packet to the sender, indicating that it has lost some amount of encoded video data for one or more frames. Only the receiver has this value, and it's only valid for video tracks.
qpSum
-
The sum of the Quantization Parameter (QP) values associated with every frame received to date on the video track described by this
RTCRtpStreamStats
object. In general, the higher this number is, the more heavily compressed the video track was. Combined withRTCReceivedRtpStreamStats.framesDecoded
orRTCInboundRtpStreamStats.framesEncoded
, you can approximate the average QP over those frames, keeping in mind that codecs often vary the quantizer values even within frames. Also keep in mind that the values of QP can vary from codec to codec, so this value is only potentially useful when compared against the same codec.
Common instance properties
The following properties are common to all WebRTC statistics objects.
id
-
A string that uniquely identifies the object that is being monitored to produce this set of statistics.
timestamp
-
A
DOMHighResTimeStamp
object indicating the time at which the sample was taken for this statistics object. type
-
A string with the value
"inbound-rtp"
, indicating the type of statistics that the object contains.
Examples
Specifications
Specification |
---|
Identifiers for WebRTC's Statistics API # dom-rtcstatstype-inbound-rtp |
Browser compatibility
BCD tables only load in the browser