This document defines a set of WebIDL objects that allow access to the statistical information about a RTCPeerConnection.
These objects are returned from the getStats API that is specified in [[WEBRTC]].
This document is incomplete, and as such is not yet suitable for implementation. However, early experimentation is encouraged.
Audio, video, or data packets transmitted over a peer-connection can be lost, and experience varying amounts of network delay. A web application implementing WebRTC expects to monitor the performance of the underlying network and media pipeline.
This document defines the statistic identifiers used by the web application to extract metrics from the user agent.
This specification defines the conformance criteria that applies to a single product: the user agent.
Implementations that use ECMAScript to implement the objects defined in this specification MUST implement them in a manner consistent with the ECMAScript Bindings defined in the Web IDL specification [[WEBIDL]], as this document uses that specification and terminology.
This specification does not define what objects a conforming implementation should generate. Specifications that refer to this specification have the need to specify conformance. They should put in their document text like this:
The concepts queue a task, and fires a simple event are defined in [[!HTML5]].
The terms event, event handlers, and event handler event types are defined in [[!HTML5]].
The terms MediaStream, MediaStreamTrack, and Consumer are defined in [[!GETUSERMEDIA]].
The terms RTCPeerConnection, RTCDataChannel, RTCDtlsTransport, RTCDtlsTransportState, RTCIceTransport, RTCIceRole and RTCPriorityType are defined in [[!WEBRTC]].
The term RTP stream is defined in [[RFC7656]] section 2.1.10.
The terms RTCStats,
RTCStats.timestamp,
RTCStats.type,
RTCStats.id,
RTCCertificate, and
statsended are defined in
[[!WEBRTC]].
The terms performance.timeOrigin and
performance.now() are
defined in [[!HIGHRES-TIME]].
The basic object of the stats model is the stats object. The following terms are defined to describe it:
An internal object that keeps a set of data values. Most monitored objects are object defined in the WebRTC API; they may be thought of as being internal properties of those objects.
A monitored object has a stable identifier "id", which is reflected in all stats objects produced from the monitored object. Stats objects may contain references to other stats objects using this "id" value. In a stats object, these references are represented by a DOMString containing "id" value of the referenced stats object.
All stats object references have type DOMString and attribute names ending in 'Id', or they have type sequence<DOMString> and attribute names ending in 'Ids'.
A monitored object changes the values it contains continuously over its lifetime, but is never visible through the getStats API call. A stats object, once returned, never changes.
The stats API is defined in [[!WEBRTC]]. It is defined to return a collection of stats objects, each of which is a dictionary inheriting directly or indirectly from the RTCStats dictionary. This API is normatively defined in [[!WEBRTC]], but is reproduced here for ease of reference.
dictionary RTCStats {
DOMHighResTimeStamp timestamp;
RTCStatsType type;
DOMString id;
};
Timestamps are expressed with DOMHighResTimeStamp [[!HIGHRES-TIME]], and are defined as performance.timeOrigin + performance.now() at the time the information is collected.
When introducing a new stats object, the following principles should be followed:
The new members of the stats dictionary need to be named according to standard practice (camelCase), as per [[API-DESIGN-PRINCIPLES]].
Names ending in "Id" (such as "transportId") are always a stats object reference; names ending in "Ids" (such as "trackIds") are always of type sequence<DOMString>, where each DOMString is a stats object reference.
If the natural name for a stats value would end in "id" (such as when the stats value is an in-protocol identifier for the monitored object), the recommended practice is to let the name end in "identifier", such as "ssrcIdentifier" or "dataChannelIdentifier".
Stats are sampled by Javascript. In general, an application will not have overall control over how often stats are sampled, and the implementation cannot know what the intended use of the stats is. There is, by design, no control surface for the application to influence how stats are generated.
Therefore, letting the implementation compute "average" rates is not a good idea, since that implies some averaging time interval that can't be set beforehand. Instead, the recommended approach is to count the number of measurements of a value and sum the measurements given even if the sum is meaningless in itself; the JS application can then compute averages over any desired time interval by calling getStats() twice, taking the difference of the two sums and dividing by the difference of the two counts.
For stats that are measured against time, such as byte counts, no separate counter is needed; one can instead divide by the difference in the timestamps.
When implementing stats objects, the following guidelines should be adhered to:
The object descriptions will say what the lifetime of a monitored object from the perspective of stats is. When a monitored object is "deleted", it no longer appears in stats; until this happens, it will appear. This may or may not correspond to the actual lifetime of an object in an implementation; what matters for this specification is what appears in stats.
If a monitored object can only exist in a few instances over the lifetime of a RTCPeerConnection, it may be simplest to consider it "eternal" and never delete it from the set of objects reported on in stats. This type of object will remain visible until the RTCPeerConnection is no longer available; it is also visible in getStats() after pc.close(). This is the default when no lifetime is mentioned in its specification.
Objects that might exist in many instances over time should have a defined time at which they are deleted, at which time a statsended event is fired on their behalf. Each event that causes deletions to happen MUST fire only one statsended event, but there are cases where one action causes multiple deletion events; for instance, an ICE restart will fire only one event containing the stats for all the discarded candidates and pairs, but will also cause a later event to be fired when the currently-in-use candidate pair and its candidates are discarded.
When a monitored object is deleted, a final stats object is produced, carrying the
values current at the time of deletion. This object will be made available using the
statsended event on the associated RTCPeerConnection. This is important
in order to report consistently on short-lived objects and to be able to consistently
report totals over the lifetime of a RTCPeerConnection.
When an object is deleted, we can guarantee that no subsequent getStats() call will contain a stats object reference that references the deleted object We also guarantee that the stats id of the deleted object will never be reused for another object. This ensures that an application that collects stats objects for deleted monitored objects will always be able to uniquely identify the object pointed to in the result of any getStats() call.
A call to getStats() touches many components of WebRTC and may take significant time to execute. The implementation may or may not utilize caching or throttling of getStats() calls for performance benefits, however any implementation must adhere to the following:
When the state of the RTCPeerConnection visibly changes as a result of an API call, a promise resolving or an event firing, subsequent new getStats() calls must return up-to-date dictionaries for the affected objects. For example, if a track is added with addTrack() subsequent getStats() calls must resolve with a corresponding RTCMediaHandlerStats object. If you call setRemoteDescription() removing a remote track, upon the promise resolving or an associated event (stream's onremovetrack or track's onmute) firing, calling getStats() must resolve with an up-to-date RTCMediaHandlerStats object.
When the statsended event is fired, subsequent getStats() calls MUST NOT return stats for the monitored object that was reported on in the statsended event.
This document, in its editors' draft form, serves as the repository for the currently defined set of stats object types including proposals for new standard types.
This document specifies the interoperable stats object types. Proposals for new object types may be made in the editors draft maintained on GitHub. New standard types may appear in future revisions of the W3C Recommendation.
If a need for a new stats object type or stats value within a stats object is found, an issue should be raised on Github, and a review process will decide on whether the stat should be added to the editors draft or not.
A pull request for a change to the editors draft may serve as guidance for the discussion, but the eventual merge is dependent on the review process.
While the WebRTC WG exist, it will serve as the review body; once it has disbanded, the W3C will have to establish appropriate review.
The level of review sought is that of the IETF process' "expert review", as defined in [[RFC5226]] section 4.1. The documentation needed includes the names of the new stats, their data types, and the definitions they are based on, specified to a level that allows interoperable implementation. The specification may consist of references to other documents.
Another specification that wishes to refer to a specific version (for instance for conformance) should refer to a dated version; these will be produced regularly when updates happen.
At times, it makes sense to retire the definition for a stats object or a stats value. When this happens, it is not advisable to simply delete it from the spec, since there may be implementations out there that use it, and it is important that the name is reserved from re-use for another, incompatible definition.
Therefore, retired stats objects are moved to a separate section in this document. Retired stats objects are moved there in their entirety; retired stats values are moved to a "partial dictionary".
If there is no evidence that the retired object definition has ever been used (such as an object that is added to the spec and renamed, redefined or removed prior to implementation), the editors can decide to just remove the object from the spec.
The type element, of type RTCStatsType, indicates the type of the
object that the RTCStats object represents. An object with a given "type" can
have only one IDL dictionary type, but multiple "type" values may indicate the same IDL
dictionary type; for example, "local-candidate" and "remote-candidate" both use the IDL
dictionary type RTCIceCandidateStats.
This specification is normative for the allowed values of RTCStatsType.
enum RTCStatsType {
"codec",
"inbound-rtp",
"outbound-rtp",
"remote-inbound-rtp",
"remote-outbound-rtp",
"csrc",
"peer-connection",
"data-channel",
"stream",
"track",
"sender",
"receiver",
"transport",
"candidate-pair",
"local-candidate",
"remote-candidate",
"certificate"
};
The following strings are valid values for RTCStatsType:
codec
Statistics for a codec that is currently being used by RTP streams being sent or
received by this RTCPeerConnection object. It is accessed by the
RTCCodecStats.
inbound-rtp
Statistics for an inbound RTP stream that is currently received with this
RTCPeerConnection object. It is accessed by the
RTCInboundRtpStreamStats.
outbound-rtp
Statistics for an outbound RTP stream that is currently sent with this
RTCPeerConnection object. It is accessed by the
RTCOutboundRtpStreamStats.
remote-inbound-rtp
Statistics for the remote endpoint's inbound RTP stream corresponding to an outbound
stream that is currently sent with this RTCPeerConnection object. It is
measured at the remote endpoint and reported in an RTCP Receiver Report (RR) or RTCP
Extended Report (XR). It is accessed by the
RTCRemoteInboundRtpStreamStats.
remote-outbound-rtp
Statistics for the remote endpoint's outbound RTP stream corresponding to an inbound
stream that is currently received with this RTCPeerConnection object. It
is measured at the remote endpoint and reported in an RTCP Sender Report (SR). It is
accessed by the RTCRemoteOutboundRtpStreamStats.
csrc
Statistics for a contributing source (CSRC) that contributed to an inbound RTP
stream. It is accessed by the RTCRtpContributingSourceStats.
peer-connection
Statistics related to the RTCPeerConnection object. It is accessed by
the RTCPeerConnectionStats.
data-channel
Statistics related to each RTCDataChannel id. It is accessed by the
RTCDataChannelStats.
stream
Contains statistics related to a specific MediaStream. It is accessed by the
RTCMediaStreamStats.
track
Contains statistics related to a specific MediaStreamTrack's attachment to an
RTCRtpSender and the corresponding media-level metrics. It is accessed by either
RTCSenderVideoTrackAttachmentStats or
RTCSenderAudioTrackAttachmentStats, both inherited from
RTCMediaHandlerStats.
The monitored "track" object is deleted when the sender it reports on has its "track" value changed to no longer refer to the same track.
sender
Contains statistics related to a specific RTCRtpSender and the corresponding
media-level metrics. It is accessed by the RTCAudioSenderStats or
the RTCVideoSenderStats depending on kind.
receiver
Contains statistics related to a specific receiver and the corresponding media-level
metrics. It is accessed by the RTCAudioReceiverStats or the
RTCVideoReceiverStats depending on kind.
transport
Transport statistics related to the RTCPeerConnection object. It is
accessed by the RTCTransportStats.
candidate-pair
ICE candidate pair statistics related to the RTCIceTransport objects. It
is accessed by the RTCIceCandidatePairStats.
A candidate pair that is not the current pair for a transport is deleted when the RTCIceTransport does an ICE restart, at the time the state changes to "new". The candidate pair that is the current pair for a transport is deleted after an ICE restart when the RTCIceTransport switches to using a candidate pair generated from the new candidates; this time doesn't correspond to any other externally observable event.
local-candidate
ICE local candidate statistics related to the RTCIceTransport objects.
It is accessed by the RTCIceCandidateStats for the local
candidate.
A local candidate is deleted when the RTCIceTransport does an ICE restart, and the candidate is no longer a member of any non-deleted candidate pair.
remote-candidate
ICE remote candidate statistics related to the RTCIceTransport objects.
It is accessed by the RTCIceCandidateStats for the remote
candidate.
A remote candidate is deleted when the RTCIceTransport does an ICE restart, and the candidate is no longer a member of any non-deleted candidate pair.
certificate
Information about a certificate used by an RTCIceTransport. It is accessed by the
RTCCertificateStats.
The dictionaries for RTP statistics are structured as a hierarchy, so that those stats that make sense in many different contexts are represented just once in IDL.
The lifetime of all RTP monitored objects starts when the RTP stream is first used: When the first RTP packet is sent or received on the SSRC it represents, or when the first RTCP packet is sent or received that refers to the SSRC of the RTP stream.
RTP monitored objects are not deleted.
The hierarchy is as follows:
RTCRtpStreamStats: Stats that apply to any end of any RTP stream
RTCReceivedRtpStreamStats: Stats measured at the receiving end of an RTP stream, known either because they're measured locally or transmitted via an RTCP Receiver Report (RR) or Extended Report (XR).
RTCInboundRtpStreamStats: Stats that can only be measured at the local receiving end of an RTP stream.
RTCRemoteInboundRtpStreamStats: Stats relevant to the remote receiving end of an RTP stream - usually computed by combining local data with data received via an RTCP RR or XR.
RTCSentRtpStreamStats: Stats measured at the sending end of an RTP stream, known either because they're measured locally or because they're received via RTCP, usually in an RTCP Sender Report (SR).
RTCRemoteOutboundRtpStreamStats: Stats relevant to the remote sending end of an RTP stream, usually computed based on an RTCP SR.
dictionary RTCRtpStreamStats : RTCStats {
unsigned long ssrc;
DOMString kind;
DOMString transportId;
DOMString codecId;
};
ssrc of type unsigned
long
The 32-bit unsigned integer value per [[RFC3550]] used to identify the source of the stream of RTP packets that this stats object concerns.
kind of type DOMString
Either "audio" or "video". This MUST match the media
type part of the information in the corresponding codec
member of RTCCodecStats, and MUST match the "kind" attribute of the
related MediaStreamTrack.
transportId of type DOMString
It is a unique identifier that is associated to the object that was inspected to
produce the RTCTransportStats associated with this RTP stream.
codecId of type DOMString
It is a unique identifier that is associated to the object that was inspected to
produce the RTCCodecStats associated with this RTP stream.
dictionary RTCCodecStats : RTCStats {
unsigned long payloadType;
RTCCodecType codecType;
DOMString transportId;
DOMString mimeType;
unsigned long clockRate;
unsigned long channels;
DOMString sdpFmtpLine;
DOMString implementation;
};
payloadType of type unsigned
long
Payload type as used in RTP encoding or decoding.
codecType of type RTCCodecType
"encode" or "decode", depending on whether this object
represents a media format that the implementation is prepared to encode or
decode.
transportId of type DOMString
The unique identifier of the transport on which this codec is being used, which
can be used to look up the corresponding RTCTransportStats
object.
mimeType of type DOMString
The codec MIME media type/subtype. e.g., video/vp8 or equivalent.
clockRate of type unsigned
long
Represents the media sampling rate.
channels of type unsigned
long
Use 2 for stereo, missing for most other cases.
sdpFmtpLine of type DOMString
The a=fmtp line in the SDP corresponding to the codec, i.e., after the colon following the PT. This defined by [[!JSEP]] in Section 5.7.
implementation of type DOMString
Identifies the implementation used. This is useful for diagnosing interoperability issues.
If too much information is given here, it increases the fingerprint surface. Since it is only given for active tracks, the incremental exposure is small.
enum RTCCodecType {
"encode",
"decode",
};
| Enumeration description | |
|---|---|
encode
|
The attached |
decode
|
The attached |
dictionary RTCReceivedRtpStreamStats : RTCRtpStreamStats {
unsigned long packetsReceived;
long packetsLost;
double jitter;
unsigned long packetsDiscarded;
unsigned long packetsRepaired;
unsigned long burstPacketsLost;
unsigned long burstPacketsDiscarded;
unsigned long burstLossCount;
unsigned long burstDiscardCount;
double burstLossRate;
double burstDiscardRate;
double gapLossRate;
double gapDiscardRate;
};
packetsReceived of type unsigned long
Total number of RTP packets received for this SSRC. At the receiving endpoint, this is calculated as defined in [[!RFC3550]] section 6.4.1. At the sending endpoint the packetsReceived can be calculated by subtracting the packets lost from the expected Highest Sequence Number reported in the RTCP Sender Report as discussed in Appendix A.3. in [[!RFC3550]].
packetsLost of type long
Total number of RTP packets lost for this SSRC. Calculated as defined in [[!RFC3550]] section 6.4.1. Note that because of how this is estimated, it can be negative if more packets are received than sent.
jitter of type double
Packet Jitter measured in seconds for this SSRC. Calculated as defined in section 6.4.1. of [[!RFC3550]].
packetsDiscarded of type unsigned long
The cumulative number of RTP packets discarded by the jitter buffer due to late or early-arrival, i.e., these packets are not played out. RTP packets discarded due to packet duplication are not reported in this metric [[XRBLOCK-STATS]]. Calculated as defined in [[!RFC7002]] section 3.2 and Appendix A.a.
packetsRepaired of type unsigned long
The cumulative number of lost RTP packets repaired after applying an error-resilience mechanism [[XRBLOCK-STATS]]. It is measured for the primary source RTP packets and only counted for RTP packets that have no further chance of repair. To clarify, the value is upper-bound to the cumulative number of lost packets. Calculated as defined in [[!RFC7509]] section 3.1 and Appendix A.b.
burstPacketsLost of type unsigned long
The cumulative number of RTP packets lost during loss bursts, Appendix A (c) of [[!RFC6958]].
burstPacketsDiscarded of type unsigned long
The cumulative number of RTP packets discarded during discard bursts, Appendix A (b) of [[!RFC7003]].
burstLossCount of type unsigned long
The cumulative number of bursts of lost RTP packets, Appendix A (e) of [[!RFC6958]].
[[!RFC3611]] recommends a Gmin (threshold) value of 16 for classifying a sequence of packet losses or discards as a burst.
burstDiscardCount of type unsigned long
The cumulative number of bursts of discarded RTP packets, Appendix A (e) of [[!RFC8015]].
burstLossRate of type double
The fraction of RTP packets lost during bursts to the total number of RTP packets expected in the bursts. As defined in Appendix A (a) of [[!RFC7004]], however, the actual value is reported without multiplying by 32768.
burstDiscardRate of type double
The fraction of RTP packets discarded during bursts to the total number of RTP packets expected in bursts. As defined in Appendix A (e) of [[!RFC7004]], however, the actual value is reported without multiplying by 32768.
gapLossRate of type double
The fraction of RTP packets lost during the gap periods. Appendix A (b) of [[!RFC7004]], however, the actual value is reported without multiplying by 32768.
gapDiscardRate of type double
The fraction of RTP packets discarded during the gap periods. Appendix A (f) of [[!RFC7004]], however, the actual value is reported without multiplying by 32768.
The RTCInboundRtpStreamStats dictionary represents the measurement metrics for the incoming RTP media stream. The timestamp reported in the statistics object is the time at which the data was sampled.
dictionary RTCInboundRtpStreamStats : RTCReceivedRtpStreamStats {
DOMString trackId;
DOMString receiverId;
DOMString remoteId;
unsigned long framesDecoded;
unsigned long long qpSum;
DOMHighResTimeStamp lastPacketReceivedTimestamp;
double averageRtcpInterval;
unsigned long fecPacketsReceived;
unsigned long long bytesReceived;
unsigned long packetsFailedDecryption;
unsigned long packetsDuplicated;
record<USVString, unsigned long> perDscpPacketsReceived;
unsigned long nackCount;
unsigned long firCount;
unsigned long pliCount;
unsigned long sliCount;
};
trackId of type DOMString
RTCReceiverAudioTrackAttachmentStats or
RTCReceiverVideoTrackAttachmentStats.
receiverId of type DOMString
The stats ID used to look up the RTCAudioReceiverStats or
RTCVideoReceiverStats object receiving this stream.
remoteId of type DOMString
The remoteId is used for looking up the remote
RTCRemoteOutboundRtpStreamStats object for the same SSRC.
framesDecoded
Only valid for video. It represents the total number of frames correctly decoded for this SSRC, i.e., frames that would be displayed if no frames are dropped.
qpSum of type unsigned long
long
Only valid for video. The sum of the QP values of frames decoded by this receiver. The count of frames is in framesDecoded.
The definition of QP value depends on the codec; for VP8, the QP value is the value carried in the frame header as the syntax element "y_ac_qi", and defined in [[RFC6386]] section 19.2. Its range is 0..127.
Note that the QP value is only an indication of quantizer values used; many formats have ways to vary the quantizer value within the frame.
lastPacketReceivedTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the last packet was received for this SSRC.
This differs from timestamp, which represents the time at which the
statistics were generated by the local endpoint.
averageRtcpInterval of type double
The average RTCP interval between two consecutive compound RTCP packets. This is calculated by the sending endpoint when sending compound RTCP reports. Compound packets must contain at least a RTCP RR or SR packet and an SDES packet with the CNAME item.
fecPacketsReceived of type unsigned long
Total number of RTP FEC packets received for this SSRC. This counter can also be incremented when receiving FEC packets in-band with media packets (e.g., with Opus).
bytesReceived of type unsigned long long
Total number of bytes received for this SSRC. Calculated as defined in [[!RFC3550]] section 6.4.1.
packetsFailedDecryption of type unsigned long
The cumulative number of RTP packets that failed to be decrypted according to the
procedures in [[!RFC3711]]. These packets are not counted by
packetsDiscarded.
packetsDuplicated of type unsigned long
packetsDiscarded.perDscpPacketsReceived of type record<USVString, unsigned long>
Total number of packets received for this SSRC, per Differentiated Services code point (DSCP) [[RFC2474]]. DSCPs are identified as decimal integers in string form. Note that due to network remapping and bleaching, these numbers are not expected to match the numbers seen on sending. Not all OSes make this information available.
firCount of type unsigned
long
Only valid for video. Count the total number of Full Intra Request (FIR) packets sent by this receiver. Calculated as defined in [[!RFC5104]] section 4.3.1. and does not use the metric indicated in [[RFC2032]], because it was deprecated by [[RFC4587]].
pliCount of type unsigned
long
Only valid for video. Count the total number of Picture Loss Indication (PLI) packets sent by this receiver. Calculated as defined in [[!RFC4585]] section 6.3.1.
nackCount of type unsigned
long
Count the total number of Negative ACKnowledgement (NACK) packets sent by this receiver. Calculated as defined in [[!RFC4585]] section 6.2.1.
sliCount of type unsigned
long
Only valid for video. Count the total number of Slice Loss Indication (SLI) packets sent by this receiver. Calculated as defined in [[!RFC4585]] section 6.3.2.
The RTCRemoteInboundRtpStreamStats dictionary represents the remote endpoint's measurement metrics for a particular incoming RTP stream (corresponding to an outgoing RTP stream at the sending endpoint). The timestamp reported in the statistics object is the time at which the corresponding RTCP RR was received.
dictionary RTCRemoteInboundRtpStreamStats : RTCReceivedRtpStreamStats {
DOMString localId;
double roundTripTime;
double fractionLost;
};
localId of type DOMString
The localId is used for looking up the local
RTCOutboundRtpStreamStats object for the same SSRC.
roundTripTime of type double
Estimated round trip time for this SSRC based on the RTCP timestamps in the RTCP Receiver Report (RR) and measured in seconds. Calculated as defined in section 6.4.1. of [[!RFC3550]]. If no RTCP Receiver Report is received with a DLSR value other than 0, the round trip time is left undefined.
fractionLost of type double
The fraction packet loss reported for this SSRC. Calculated as defined in [[!RFC3550]] section 6.4.1 and Appendix A.3.
dictionary RTCSentRtpStreamStats : RTCRtpStreamStats {
unsigned long packetsSent;
unsigned long packetsDiscardedOnSend;
unsigned long fecPacketsSent;
unsigned long long bytesSent;
unsigned long long bytesDiscardedOnSend;
};
packetsSent of type unsigned
long
Total number of RTP packets sent for this SSRC. Calculated as defined in [[!RFC3550]] section 6.4.1.
packetsDiscardedOnSend of type unsigned long
Total number of RTP packets for this SSRC that have been discarded due to socket errors, i.e. a socket error occured when handing the packets to the socket. This might happen due to various reasons, including full buffer or no available memory.
fecPacketsSent of type unsigned long
Total number of RTP FEC packets sent for this SSRC. This counter can also be incremented when sending FEC packets in-band with media packets (e.g., with Opus).
bytesSent of type unsigned
long long
Total number of bytes sent for this SSRC. Calculated as defined in [[!RFC3550]] section 6.4.1.
bytesDiscardedOnSend of type unsigned long long
Total number of bytes for this SSRC that have been discarded due to socket errors, i.e. a socket error occured when handing the packets containing the bytes to the socket. This might happen due to various reasons, including full buffer or no available memory. Calculated as defined in [[!RFC3550]] section 6.4.1.
The RTCOutboundRtpStreamStats dictionary represents the measurement metrics for the outgoing RTP stream. The timestamp reported in the statistics object is the time at which the data was sampled.
dictionary RTCOutboundRtpStreamStats : RTCSentRtpStreamStats {
DOMString trackId;
DOMString senderId;
DOMString remoteId;
DOMHighResTimeStamp lastPacketSentTimestamp;
double targetBitrate;
unsigned long framesEncoded;
unsigned long long qpSum;
double totalEncodeTime;
double averageRtcpInterval;
RTCQualityLimitationReason qualityLimitationReason;
record<DOMString, double> qualityLimitationDurations;
record<USVString, unsigned long> perDscpPacketsSent;
unsigned long nackCount;
unsigned long firCount;
unsigned long pliCount;
unsigned long sliCount;
};
trackId of type DOMString
RTCSenderAudioTrackAttachmentStats or
RTCSenderVideoTrackAttachmentStats.
senderId of type DOMString
The stats ID used to look up the RTCAudioSenderStats or
RTCVideoSenderStats object sending this stream.
remoteId of type DOMString
The remoteId is used for looking up the remote
RTCRemoteInboundRtpStreamStats object for the same SSRC.
lastPacketSentTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the last packet was sent for this SSRC. This
differs from timestamp, which represents the time at which the
statistics were generated by the local endpoint.
targetBitrate of type double
It is the current target bitrate configured for this particular SSRC and is the Transport Independent Application Specific (TIAS) bitrate [[!RFC3890]]. Typically, the target bitrate is a configuration parameter provided to the codec's encoder and does not count the size of the IP or other transport layers like TCP or UDP. It is measured in bits per second and the bitrate is calculated over a 1 second window.
framesEncoded of type long
Only valid for video. It represents the total number of frames successfully encoded for this RTP media stream.
qpSum of type unsigned long
long
Only valid for video. The sum of the QP values of frames encoded by this sender. The count of frames is in framesEncoded.
The definition of QP value depends on the codec; for VP8, the QP value is the value carried in the frame header as the syntax element "y_ac_qi", and defined in [[RFC6386]] section 19.2. Its range is 0..127.
Note that the QP value is only an indication of quantizer values used; many formats have ways to vary the quantizer value within the frame.
totalEncodeTime of type double
Total number of seconds that has been spent encoding the framesEncoded frames of this stream. The average encode time can be calculated by dividing this value with framesEncoded. The time it takes to encode one frame is the time passed between feeding the encoder a frame and the encoder returning encoded data for that frame. This does not include any additional time it may take to packetize the resulting data.
averageRtcpInterval of type double
The average RTCP interval between two consecutive compound RTCP packets. This is calculated by the sending endpoint when sending compound RTCP reports. Compound packets must contain at least a RTCP RR or SR packet and an SDES packet with the CNAME item.
qualityLimitationReason of type RTCQualityLimitationReason
Only valid for video. The current reason for limiting the resolution and/or framerate, or "none" if not limited.
qualityLimitationDurations of type record<DOMString, double>
Only valid for video. A record of the total time, in seconds, that this stream has spent in each quality limitation state. The record includes a mapping for all RTCQualityLimitationReason types, including "none".
The sum of all entries minus qualityLimidationDurations["none"]
gives the total time that the stream has been limited.
perDscpPacketsSent of type record<USVString, unsigned long>
Total number of packets sent for this SSRC, per DSCP. DSCPs are identified as decimal integers in string form.
nackCount of type unsigned
long
Count the total number of Negative ACKnowledgement (NACK) packets received by this sender. Calculated as defined in [[!RFC4585]] section 6.2.1.
firCount of type unsigned
long
Only valid for video. Count the total number of Full Intra Request (FIR) packets received by this sender. Calculated as defined in [[!RFC5104]] section 4.3.1. and does not use the metric indicated in [[RFC2032]], because it was deprecated by [[RFC4587]].
pliCount of type unsigned
long
Only valid for video. Count the total number of Picture Loss Indication (PLI) packets received by this sender. Calculated as defined in [[!RFC4585]] section 6.3.1.
sliCount of type unsigned
long
Only valid for video. Count the total number of Slice Loss Indication (SLI) packets received by this sender. Calculated as defined in [[!RFC4585]] section 6.3.2.
enum RTCQualityLimitationReason {
"none",
"cpu",
"bandwidth",
"other",
};
| Enumeration description | |
|---|---|
none
|
The resolution and/or framerate is not limited. |
cpu
|
The resolution and/or framerate is primarily limited due to CPU load. |
bandwidth
|
The resolution and/or framerate is primarily limited due to congestion cues during bandwidth estimation. Typical, congestion control algorithms use inter-arrival time, round-trip time, packet or other congestion cues to perform bandwidth estimation. |
other
|
The resolution and/or framerate is primarily limited for a reason other than the above. |
The RTCRemoteOutboundRtpStreamStats dictionary represents the remote endpoint's measurement metrics for its outgoing RTP stream (corresponding to an outgoing RTP stream at the sending endpoint). The timestamp reported in the statistics object is the time at which the corresponding RTCP SR was received.
dictionary RTCRemoteOutboundRtpStreamStats : RTCSentRtpStreamStats {
DOMString localId;
DOMHighResTimeStamp remoteTimestamp;
};
localId of type DOMString
The localId is used for looking up the local
RTCInboundRtpStreamStats object for the same SSRC.
remoteTimestamp of type DOMHighResTimeStamp
remoteTimestamp, of type DOMHighResTimeStamp
[[!HIGHRES-TIME]], represents the remote timestamp at which these statistics were
sent by the remote endpoint. This differs from timestamp, which
represents the time at which the statistics were generated or received by the
local endpoint. The remoteTimestamp, if present, is derived from the
NTP timestamp in an RTCP Sender Report (SR) packet, which reflects the remote
endpoint's clock. That clock may not be synchronized with the local clock.
The RTCRtpContributingSourceStats dictionary represents the measurement
metrics for a contributing source (CSRC) that is contributing to an incoming RTP stream.
Each contributing source produces a stream of RTP packets, which are combined by a mixer
into a single stream of RTP packets that is ultimately received by the WebRTC endpoint.
Information about the sources that contributed to this combined stream may be provided in
the CSRC list or [[RFC6465]] header extension of received RTP packets. The
timestamp of this stats object is the
most recent time an RTP packet the source contributed to was received and counted by
packetsContributedTo.
dictionary RTCRtpContributingSourceStats : RTCStats {
unsigned long contributorSsrc;
DOMString inboundRtpStreamId;
unsigned long packetsContributedTo;
double audioLevel;
};
contributorSsrc of type unsigned long
The SSRC identifier of the contributing source represented by this stats object, as defined by [[!RFC3550]]. It is a 32-bit unsigned integer that appears in the CSRC list of any packets the relevant source contributed to.
inboundRtpStreamId of type DOMString
The ID of the RTCInboundRtpStreamStats object representing
the inbound RTP stream that this contributing source is contributing to.
packetsContributedTo of type unsigned long
The total number of RTP packets that this contributing source contributed to.
This value is incremented each time a packet is counted by
RTCInboundRtpStreamStats.packetsReceived, and the packet's CSRC list
(as defined by [[!RFC3550]] section 5.1) contains the SSRC identifier of this
contributing source, contributorSsrc.
audioLevel of type double
Present if the last received RTP packet that this source contributed to contained
an [[!RFC6465]] mixer-to-client audio level header extension. The value of
audioLevel is between 0..1 (linear), where 1.0 represents 0 dBov, 0
represents silence, and 0.5 represents approximately 6 dBSPL change in the sound
pressure level from 0 dBov.
The [[!RFC6465]] header extension contains values in the range 0..127, in units
of -dBov, where 127 represents silence. To convert these values to the linear
0..1 range of audioLevel, a value of 127 is converted to 0, and all
other values are converted using the equation: f(rfc6465_level) =
10^(-rfc6465_level/20).
dictionary RTCPeerConnectionStats : RTCStats {
unsigned long dataChannelsOpened;
unsigned long dataChannelsClosed;
unsigned long dataChannelsRequested;
unsigned long dataChannelsAccepted;
};
dataChannelsOpened of type unsigned long
Represents the number of unique DataChannels that have entered the "open" state during their lifetime.
dataChannelsClosed of type unsigned long
Represents the number of unique DataChannels that have left the "open" state during their lifetime (due to being closed by either end or the underlying transport being closed). DataChannels that transition from "connecting" to "closing" or "closed" without ever being "open" are not counted in this number.
dataChannelsRequested of type unsigned long
Represents the number of unique DataChannels returned from a successful createDataChannel() call on the RTCPeerConnection. If the underlying data transport is not established, these may be in the "connecting" state.
dataChannelsAccepted of type unsigned long
Represents the number of unique DataChannels signaled in a "datachannel" event on the RTCPeerConnection.
The total number of open data channels at any time can be calculated as dataChannelsOpened - dataChannelsClosed. This number is always positive.
The sum of dataChannelsRequested and dataChannelsAccepted is always greater than or equal to dataChannelsOpened - the difference is equal to the number of channels that have been requested, but have not reached the "open" state.
dictionary RTCMediaStreamStats : RTCStats {
DOMString streamIdentifier;
sequence<DOMString> trackIds;
};
dictionary RTCMediaHandlerStats : RTCStats {
DOMString trackIdentifier;
boolean remoteSource;
boolean ended;
DOMString kind;
RTCPriorityType priority;
};
trackIdentifier of type DOMString
Represents the id property of the track.
remoteSource of type boolean
ended of type boolean
Reflects the "ended" state of the track.
kind of type DOMString
Either "audio" or "video". This reflects the "kind"
attribute of the MediaStreamTrack, see [[!GETUSERMEDIA]].
priority of type RTCPriorityType
Indicates the priority set for the track. It is specified in [[!RTCWEB-TRANSPORT]], Section 4.
dictionary RTCVideoHandlerStats : RTCMediaHandlerStats {
unsigned long frameWidth;
unsigned long frameHeight;
double framesPerSecond;
};
frameWidth of type unsigned
long
Represents the width of the last processed frame for this track. Before the first frame is processed this attribute is missing.
frameHeight of type unsigned
long
Represents the height of the last processed frame for this track. Before the first frame is processed this attribute is missing.
framesPerSecond of type double
Represents the nominal FPS value before the degradation preference is applied. It is the number of complete frames in the last second. For sending tracks it is the current captured FPS and for the receiving tracks it is the current decoding framerate.
An RTCVideoSenderStats object represents the stats about one video sender of a RTCPeerConnection object for which one calls getStats.
It appears in the stats as soon as the sender is added by either addTrack or addTransceiver, or by media negotiation.
dictionary RTCVideoSenderStats : RTCVideoHandlerStats {
unsigned long framesCaptured;
unsigned long framesSent;
unsigned long hugeFramesSent;
unsigned long keyFramesSent;
};
framesCaptured of type unsigned long
Represents the total number of frames captured, before encoding, for this
RTCRtpSender (or for this MediaStreamTrack, if type is
"track"). For example, if type is "sender"
and this sender's track represents a camera, then this is the number of frames
produced by the camera for this track while being sent by this sender, combined
with the number of frames produced by all tracks previously attached to this
sender while being sent by this sender. Framerates can vary due to hardware
limitations or environmental factors such as lighting conditions.
framesSent of type unsigned
long
Represents the total number of frames sent by this RTCRtpSender (or for this
MediaStreamTrack, if type is "track").
hugeFramesSent of type unsigned long
Represents the total number of huge frames sent by this RTCRtpSender (or for this
MediaStreamTrack, if type is "track"). Huge frames, by
definition, are frames that have an encoded size at least 2.5 times the average
size of the frames. The average size of the frames is defined as the target
bitrate per second divided by the target fps at the time the frame was encoded.
These are usually complex to encode frames with a lot of changes in the picture.
This can be used to estimate, e.g slide changes in the streamed presentation. If
a huge frame is also a key frame, then both counters hugeFramesSent and
keyFramesSent are incremented.
The multiplier of 2.5 is choosen from analyzing encoded frame sizes for a sample presentation using webrtc standalone implementation. 2.5 is a reasonably large multiplier which still caused all slide change events to be identified as a huge frames. It, however, produced 1.4% of false positive slide change detections which is deemed reasonable.
keyFramesSent of type unsigned long
Represents the total number of key frames sent by this RTCRtpSender (or for this
MediaStreamTrack, if type is "track"), such as
Infra-frames in VP8 [[RFC6386]] or I-frames in H.264 [[RFC6184]]. This is a
subset of framesSent. framesSent - keyFramesSent gives
you the number of delta frames sent.
An RTCSenderVideoTrackAttachmentStats object represents the stats about one attachment of a video MediaStreamTrack to the RTCPeerConnection object for which one calls getStats.
It appears in the stats as soon as it is attached (via addTrack, via addTransceiver, via replaceTrack on an RTCRtpSender object).
If a video track is attached twice (via addTransceiver or replaceTrack), there will be two RTCSenderVideoTrackAttachmentStats objects, one for each attachment. They will have the same "trackIdentifier" attribute, but different "id" attributes.
If the track is detached from the RTCPeerConnection (via removeTrack or via replaceTrack),
it continues to appear, but with the "objectDeleted" member set to true.
dictionary RTCSenderVideoTrackAttachmentStats : RTCVideoSenderStats {
};
An RTCVideoReceiverStats object represents the stats about one video receiver of a RTCPeerConnection object for which one calls getStats.
It appears in the stats as soon as the RTCRtpReceiver is added by either addTrack or addTransceiver, or by media negotiation.
dictionary RTCVideoReceiverStats : RTCVideoHandlerStats {
DOMHighResTimeStamp estimatedPlayoutTimestamp;
double jitterBufferDelay;
unsigned long long jitterBufferEmittedCount;
unsigned long framesReceived;
unsigned long keyFramesReceived;
unsigned long framesDecoded;
unsigned long framesDropped;
unsigned long partialFramesLost;
unsigned long fullFramesLost;
};
estimatedPlayoutTimestamp of type DOMHighResTimeStamp
This is the estimated playout time of this receiver's track. The playout time is the NTP timestamp of the last playable video frame that has a known timestamp (from an RTCP SR packet mapping RTP timestamps to NTP timestamps), extrapolated with the time elapsed since it was ready to be played out. This is the "current time" of the track in NTP clock time of the sender and can be present even if there is no video currently playing.
This can be useful for estimating how much audio and video is out of sync for two
tracks from the same remote source,
audioTrackStats.estimatedPlayoutTimestamp -
videoTrackStats.estimatedPlayoutTimestamp.
jitterBufferDelay of type double
It is the sum of the time, in seconds, each frame takes from the time it is
received and to the time it exits the jitter buffer. This increases upon frames
exiting, having completed their time in the buffer (incrementing
jitterBufferEmittedCount). The average jitter buffer delay can be
calculated by dividing the jitterBufferDelay with the
jitterBufferEmittedCount.
jitterBufferEmittedCount of type unsigned long long
The total number of frames that have come out of the jitter buffer (increasing
jitterBufferDelay).
framesReceived of type unsigned long
Represents the total number of complete frames received for this receiver. This metric is incremented when the complete frame is received.
keyFramesReceived of type unsigned long
Represents the total number of complete key frames received for this
MediaStreamTrack, such as Infra-frames in VP8 [[RFC6386]] or I-frames in H.264
[[RFC6184]]. This is a subset of framesReceived.
framesReceived - keyFramesReceived gives you the number of delta
frames received. This metric is incremented when the complete key frame is
received. It is not incremented if a partial key frames is received and sent for
decoding, i.e., the frame could not be recovered via retransmission or FEC.
framesDecoded of type unsigned long
Only valid for video. It represents the total number of frames correctly decoded for this SSRC, i.e., frames that would be displayed if no frames are dropped.
framesDropped of type unsigned long
The total number of frames dropped predecode or dropped because the frame missed its display deadline for this receiver's track. As defined in Appendix A (g) of [[!RFC7004]].
partialFramesLost of type unsigned long
The cumulative number of partial frames lost, as defined in Appendix A (j) of [[!RFC7004]]. This metric is incremented when the frame is sent to the decoder. If the partial frame is received and recovered via retransmission or FEC before decoding, the framesReceived counter is incremented.
fullFramesLost of type unsigned long
The cumulative number of full frames lost, as defined in Appendix A (i) of [[!RFC7004]].
dictionary RTCAudioHandlerStats : RTCMediaHandlerStats {
double audioLevel;
double totalAudioEnergy;
boolean voiceActivityFlag;
double totalSamplesDuration;
};
audioLevel of type double
The value is between 0..1 (linear), where 1.0 represents 0 dBov, 0 represents silence, and 0.5 represents approximately 6 dBSPL change in the sound pressure level from 0 dBov.
The "audio level" value defined in [[RFC6464]] (as 0..127, where 0 represents 0 dBov, 126 represents -126 dBov and 127 represents silence) is obtained by the calculation given in appendix A of [[!RFC6465]]: informally, level = -round(log10(audioLevel) * 20), with audioLevel 0.0 and values above 127 mapped to 127.
The audioLevel represents the output audio level of the track; thus, if the track is sourced from an RTCReceiver, does no audio processing, has a constant level, and has a volume setting of 1.0, the audio level is expected to be the same as the audio level of the source SSRC, while if the volume setting is 0.5, the audioLevel is expected to be half that value.
For outgoing audio tracks, the audioLevel is the level of the audio being sent.
The audioLevel is averaged over some small interval, using the algortihm described under totalAudioEnergy. The interval used is implementation dependent.
totalAudioEnergy of type double
This value MUST be computed as follows: for each audio sample sent/received for
this object (and counted by totalSamplesSent or
totalSamplesReceived), add the sample's value divided by the
highest-intensity encodable value, squared and then multiplied by the duration of
the sample in seconds. In other words, duration *
Math.pow(energy/maxEnergy, 2).
This can be used to obtain a root mean square (RMS) value that uses the same
units as audioLevel, as defined in [[RFC6464]]. It can be
converted to these units using the formula
Math.sqrt(totalAudioEnergy/totalSamplesDuration). This calculation
can also be performed using the differences between the values of two different
getStats() calls, in order to compute the average audio level over
any desired time interval. In other words, do Math.sqrt((energy2 -
energy1)/(duration2 - duration1)).
For example, if a 10ms packet of audio is received with an RMS of 0.5 (out of
1.0), this should add 0.5 * 0.5 * 0.01 = 0.0025 to
totalAudioEnergy. If another 10ms packet with an RMS of 0.1 is
received, this should similarly add 0.0001 to
totalAudioEnergy. Then,
Math.sqrt(totalAudioEnergy/totalSamplesDuration) becomes
Math.sqrt(0.0026/0.02) = 0.36, which is the same value that would be
obtained by doing an RMS calculation over the contiguous 20ms segment of audio.
voiceActivityFlag of type boolean
Whether the last RTP packet sent or played out by this track contained voice activity or not based on the presence of the V bit in the extension header, as defined in [[RFC6464]].
This value indicates the voice activity in the latest RTP packet played out from
a given SSRC, and is defined in the
RTCRtpSynchronizationSource.voiceActivityFlag of [[WEBRTC].
totalSamplesDuration of type double
Represents the total duration in seconds of all samples that have sent or
received (and thus counted by totalSamplesSent or
totalSamplesReceived). Can be used with
totalAudioEnergy to compute an average audio level over
different intervals.
An RTCAudioSenderStats object represents the stats about one audio sender of a RTCPeerConnection object for which one calls getStats.
It appears in the stats as soon as the RTCRtpSender is added by either addTrack or addTransceiver, or by media negotiation.
dictionary RTCAudioSenderStats : RTCAudioHandlerStats {
double echoReturnLoss;
double echoReturnLossEnhancement;
unsigned long long totalSamplesSent;
};
echoReturnLoss of type double
Only present while the sender is sending a track sourced from a microphone where echo cancellation is applied. Calculated in decibels, as defined in [[!ECHO]] (2012) section 3.14.
echoReturnLossEnhancement of type double
Only present while the sender is sending a track sourced from a microphone where echo cancellation is applied. Calculated in decibels, as defined in [[!ECHO]] (2012) section 3.15.
totalSamplesSent of type unsigned long long
The total number of samples that have been sent by this sender.
An RTCSenderAudioTrackAttachmentStats object represents the stats about one attachment of an audio MediaStreamTrack to the RTCPeerConnection object for which one calls getStats.
It appears in the stats as soon as it is attached (via addTrack, via addTransceiver, via replaceTrack on an RTCRtpSender object).
If an audio track is attached twice (via addTransceiver or replaceTrack), there will be two RTCSenderAudioTrackAttachmentStats objects, one for each attachment. They will have the same "trackIdentifier" attribute, but different "id" attributes.
If the track is detached from the RTCPeerConnection (via removeTrack or via replaceTrack),
it continues to appear, but with the "objectDeleted" member set to true.
dictionary RTCSenderAudioTrackAttachmentStats : RTCAudioSenderStats {
};
An RTCAudioReceiverStats object represents the stats about one audio receiver of a RTCPeerConnection object for which one calls getStats.
It appears in the stats as soon as the RTCRtpReceiver is added by either addTrack or addTransceiver, or by media negotiation.
dictionary RTCAudioReceiverStats : RTCAudioHandlerStats {
DOMHighResTimeStamp estimatedPlayoutTimestamp;
double jitterBufferDelay;
unsigned long long jitterBufferEmittedCount;
unsigned long long totalSamplesReceived;
unsigned long long concealedSamples;
unsigned long long concealmentEvents;
};
estimatedPlayoutTimestamp of type DOMHighResTimeStamp
This is the estimated playout time of this receiver's track. The playout time is the NTP timestamp of the last playable sample that has a known timestamp (from an RTCP SR packet mapping RTP timestamps to NTP timestamps), extrapolated with the time elapsed since it was ready to be played out. This is the "current time" of the track in NTP clock time of the sender and can be present even if there is no audio currently playing.
This can be useful for estimating how much audio and video is out of sync for two
tracks from the same source, audioTrackStats.estimatedPlayoutTimestamp -
videoTrackStats.estimatedPlayoutTimestamp.
jitterBufferDelay of type double
It is the sum of the time, in seconds, each sample takes from the time it is
received and to the time it exits the jitter buffer. This increases upon samples
exiting, having completed their time in the buffer (incrementing
jitterBufferEmittedCount). The average jitter buffer delay can be
calculated by dividing the jitterBufferDelay with the
jitterBufferEmittedCount.
jitterBufferEmittedCount of type unsigned long long
The total number of samples that have come out of the jitter buffer (increasing
jitterBufferDelay).
totalSamplesReceived of type unsigned long long
The total number of samples that have been received by this receiver. This includes concealedSamples.
concealedSamples of type unsigned long long
The total number of samples that are concealed samples. A concealed sample is a sample that is based on data that was synthesized to conceal packet loss and does not represent incoming data.
concealmentEvents of type unsigned long long
The number of concealment events. This counter increases every time a concealed sample is synthesized after a non-concealed sample. That is, multiple consecutive concealed samples will increase the concealedSamples count multiple times but is a single concealment event.
dictionary RTCDataChannelStats : RTCStats {
DOMString label;
DOMString protocol;
long dataChannelIdentifier;
DOMString transportId;
RTCDataChannelState state;
unsigned long messagesSent;
unsigned long long bytesSent;
unsigned long messagesReceived;
unsigned long long bytesReceived;
};
label of type DOMString
protocol of type DOMString
dataChannelIdentifier of type long
The "id" attribute of the RTCDataChannel object.
transportId of type DOMString
state of type RTCDataChannelState
messagesSent of type unsigned long
Represents the total number of API "message" events sent.
bytesSent of type unsigned
long long
Represents the total number of payload bytes sent on this
RTCDatachannel, i.e., not including headers or padding.
messagesReceived of type unsigned long
Represents the total number of API "message" events received.
bytesReceived of type unsigned long long
Represents the total number of bytes received on this
RTCDatachannel, i.e., not including headers or padding.
An RTCTransportStats object represents the stats corresponding to an
RTCDtlsTransport and its underlying
RTCIceTransport. When RTCP multiplexing is used, one transport is
used for both RTP and RTCP. Otherwise, RTP and RTCP will be sent on separate transports,
and rtcpTransportStatsId can be used to pair the resulting
RTCTransportStats objects. Additionally, when bundling is used, a single
transport will be used for all MediaStreamTracks in the bundle group.
If bundling is not used, different MediaStreamTrack will use
different transports. RTCP multiplexing and bundling are described in [[!WEBRTC]].
dictionary RTCTransportStats : RTCStats {
unsigned long packetsSent;
unsigned long packetsReceived;
unsigned long long bytesSent;
unsigned long long bytesReceived;
DOMString rtcpTransportStatsId;
RTCIceRole iceRole;
RTCDtlsTransportState dtlsState;
DOMString selectedCandidatePairId;
DOMString localCertificateId;
DOMString remoteCertificateId;
DOMString tlsVersion;
DOMString dtlsCipher;
DOMString srtpCipher;
DOMString tlsGroup;
};
packetsSent of type unsigned
long
Represents the total number of packets sent over this transport.
packetsReceived of type unsigned long
Represents the total number of packets received on this transport.
bytesSent of type unsigned
long long
Represents the total number of payload bytes sent on this
PeerConnection, i.e., not including headers or padding.
bytesReceived of type unsigned long long
Represents the total number of bytes received on this
PeerConnection, i.e., not including headers or padding.
rtcpTransportStatsId of type DOMString
If RTP and RTCP are not multiplexed, this is the id of the transport
that gives stats for the RTCP component, and this record has only the RTP
component stats.
iceRole of type RTCIceRole
Set to the current value of the "role" attribute of the underlying RTCDtlsTransport's "transport".
dtlsState of type RTCDtlsTransportState
Set to the current value of the "state" attribute of the underlying RTCDtlsTransport.
selectedCandidatePairId of type DOMString
It is a unique identifier that is associated to the object that was inspected to
produce the RTCIceCandidatePairStats associated with this transport.
localCertificateId of type DOMString
For components where DTLS is negotiated, give local certificate.
remoteCertificateId of type DOMString
For components where DTLS is negotiated, give remote certificate.
tlsVersion of type DOMString
For components where DTLS is negotiated, the TLS version agreed. Only present after DTLS negotiation is complete.
The value comes from ServerHello.supported_versions if present, otherwise from ServerHello.version. It is represented as four hex digits, representing the two bytes of the version.
dtlsCipher of type DOMString
Descriptive name of the cipher suite used for the DTLS transport, as defined in the "Description" column of the IANA cipher suite registry [[!IANA-TLS-CIPHERS]].
srtpCipher of type DOMString
Descriptive name of the protection profile used for the SRTP transport, as defined in the "Profile" column of the IANA DTLS-SRTP protection profile registry [[!IANA-DTLS-SRTP]] and described further in [[RFC5764]].
tlsGroup of type DOMString
Descriptive name of the group used for the encryption, as defined in the "Description" column of the IANA TLS Supported Groups registry [[!IANA-TLS-GROUPS]].
RTCIceCandidateStats reflects the properties of a candidate in
Section 15.1 of [[!RFC5245]]. It corresponds to a RTCIceCandidate object.
dictionary RTCIceCandidateStats : RTCStats {
DOMString transportId;
RTCNetworkType networkType;
DOMString? address;
long port;
DOMString protocol;
RTCIceCandidateType candidateType;
long priority;
DOMString url;
DOMString relayProtocol;
boolean deleted = false;
};
transportId of type DOMString
It is a unique identifier that is associated to the object that was inspected to
produce the RTCTransportStats associated with this candidate.
networkType of type RTCNetworkType
Represents the type of network interface used by the base of a local candidate (the address the ICE agent sends from). Only present for local candidates; it's not possible to know what type of network interface a remote candidate is using.
networkType of the
relevant candidate would be "wifi", even when the next hop is over a
cellular connection.
This reveals information that would otherwise not be available to web pages, which increases the fingerprint surface.
address of type DOMString
It is the address of the candidate, allowing for IPv4 addresses, IPv6 addresses, and fully qualified domain names (FQDNs). See [[!RFC5245]] section 15.1 for details.
The user agent should make sure that only remote candidate addresses that the web application has configured on the corresponding RTCPeerConnection are exposed; This is especially important for peer reflexive remote candidates. By default, the user agent MUST leave the 'address' member as null in the RTCICECandidateStats dictionary of any remote candidate. Once a RTCPeerConnection instance learns on an address by the web application using addIceCandidate, the user agent can expose the 'address' member value in any remote RTCIceCandidateStats dictionary of the corresponding RTCPeerConnection that matches the newly learnt address.
port of type long
It is the port number of the candidate.
protocol of type DOMString
Valid values for transport is one of udp and tcp. Based
on the "transport" defined in [[!RFC5245]] section 15.1.
relayProtocol of type DOMString
It is the protocol used by the endpoint to communicate with the TURN server. This
is only present for local candidates. Valid values are
udp, tcp, or tls.
candidateType of type RTCIceCandidateType
This enumeration is defined in [[WEBRTC]].
priority of type long
Calculated as defined in [[!RFC5245]] section 15.1.
url of type DOMString
For local candidates this is the URL of the ICE server from which the candidate was obtained. It is the same as the url surfaced in the RTCPeerConnectionIceEvent.
For remote candidates, this property is not present.
deleted of type boolean, defaulting to false
For local candidates, true indicates that the candidate has been
deleted/freed as described by [[!RFC5245]]. For host candidates, this means that
any network resources (typically a socket) associated with the candidate have
been released. For TURN candidates, this means the TURN allocation is no longer
active.
For remote candidates, this property is not present.
enum RTCNetworkType {
"bluetooth",
"cellular",
"ethernet",
"wifi",
"wimax",
"vpn",
"unknown"
};
| Enumeration description | |
|---|---|
bluetooth
|
A Bluetooth connection. |
cellular
|
A cellular connection (e.g., EDGE, HSPA, LTE, etc.). |
ethernet
|
An Ethernet connection. |
wifi
|
A Wi-Fi connection. |
wimax
|
A WiMAX connection. |
vpn
|
The connection runs over a VPN. The underlying network type is not available. |
unknown
|
The user agent is unable or unwilling to identify the underlying connection technology. |
dictionary RTCIceCandidatePairStats : RTCStats {
DOMString transportId;
DOMString localCandidateId;
DOMString remoteCandidateId;
RTCStatsIceCandidatePairState state;
boolean nominated;
unsigned long packetsSent;
unsigned long packetsReceived;
unsigned long long bytesSent;
unsigned long long bytesReceived;
DOMHighResTimeStamp lastPacketSentTimestamp;
DOMHighResTimeStamp lastPacketReceivedTimestamp;
DOMHighResTimeStamp firstRequestTimestamp;
DOMHighResTimeStamp lastRequestTimestamp;
DOMHighResTimeStamp lastResponseTimestamp;
double totalRoundTripTime;
double currentRoundTripTime;
double availableOutgoingBitrate;
double availableIncomingBitrate;
unsigned long circuitBreakerTriggerCount;
unsigned long long requestsReceived;
unsigned long long requestsSent;
unsigned long long responsesReceived;
unsigned long long responsesSent;
unsigned long long retransmissionsReceived;
unsigned long long retransmissionsSent;
unsigned long long consentRequestsSent;
DOMHighResTimeStamp consentExpiredTimestamp;
};
transportId of type DOMString
It is a unique identifier that is associated to the object that was inspected to
produce the RTCTransportStats associated with this candidate pair.
localCandidateId of type DOMString
It is a unique identifier that is associated to the object that was inspected to
produce the RTCIceCandidateStats for the local candidate
associated with this candidate pair.
remoteCandidateId of type DOMString
It is a unique identifier that is associated to the object that was inspected to
produce the RTCIceCandidateStats for the remote candidate
associated with this candidate pair.
state of type RTCStatsIceCandidatePairState
Represents the state of the checklist for the local and remote candidates in a pair.
nominated of type boolean
Related to updating the nominated flag described in Section 7.1.3.2.4 of [[!RFC5245]].
packetsSent of type unsigned
long
Represents the total number of packets sent on this candidate pair.
packetsReceived of type unsigned long
Represents the total number of packets received on this candidate pair.
bytesSent of type unsigned
long long
Represents the total number of payload bytes sent on this candidate pair, i.e., not including headers or padding.
bytesReceived of type unsigned long long
Represents the total number of payload bytes received on this candidate pair, i.e., not including headers or padding.
lastPacketSentTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the last packet was sent on this particular candidate pair, excluding STUN packets.
lastPacketReceivedTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the last packet was received on this particular candidate pair, excluding STUN packets.
firstRequestTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the first STUN request was sent on this particular candidate pair.
lastRequestTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the last STUN request was sent on this
particular candidate pair. The average interval between two consecutive
connectivity checks sent can be calculated with (lastRequestTimestamp -
firstRequestTimestamp) / requestsSent.
lastResponseTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the last STUN response was received on this particular candidate pair.
totalRoundTripTime of type double
Represents the sum of all round trip time measurements in seconds since the
beginning of the session, based on STUN connectivity check [[!STUN-PATH-CHAR]]
responses (responsesReceived), including those that reply to requests that are
sent in order to verify consent [[!RFC7675]]. The average round trip time can be
computed from totalRoundTripTime by dividing it by
responsesReceived.
currentRoundTripTime of type double
Represents the latest round trip time measured in seconds, computed from both STUN connectivity checks [[!STUN-PATH-CHAR]], including those that are sent for consent verification [[!RFC7675]].
availableOutgoingBitrate of type double
It is calculated by the underlying congestion control by combining the available bitrate for all the outgoing RTP streams using this candidate pair. The bitrate measurement does not count the size of the IP or other transport layers like TCP or UDP. It is similar to the TIAS defined in [[!RFC3890]], i.e., it is measured in bits per second and the bitrate is calculated over a 1 second window.
Implementations that do not calculate a sender-side estimate MUST leave this
undefined. Additionally, the value MUST be undefined for candidate pairs that
were never used. For pairs in use, the estimate is normally no lower than the
bitrate for the packets sent at lastPacketSentTimestamp, but might
be higher. For candidate pairs that are not currently in use but were used
before, implementations MUST return undefined.
availableIncomingBitrate of type double
It is calculated by the underlying congestion control by combining the available bitrate for all the incoming RTP streams using this candidate pair. The bitrate measurement does not count the size of the IP or other transport layers like TCP or UDP. It is similar to the TIAS defined in [[!RFC3890]], i.e., it is measured in bits per second and the bitrate is calculated over a 1 second window.
Implementations that do not calculate a receiver-side estimate MUST leave this
undefined. Additionally, the value should be undefined for candidate pairs that
were never used. For pairs in use, the estimate is normally no lower than the
bitrate for the packets received at lastPacketReceivedTimestamp, but
might be higher. For candidate pairs that are not currently in use but were used
before, implementations MUST return undefined.
circuitBreakerTriggerCount of type unsigned long
Represents the number of times the circuit breaker is triggered for this particular 5-tuple. Ceasing transmission when a circuit breaker is triggered is defined in Section 4.5 of [[!RFC8083]]. The field MUST return undefined for user-agents that do not implement the circuit-breaker algorithm.
requestsReceived of type unsigned long long
Represents the total number of connectivity check requests received (including retransmissions). It is impossible for the receiver to tell whether the request was sent in order to check connectivity or check consent, so all connectivity checks requests are counted here.
requestsSent of type unsigned long long
Represents the total number of connectivity check requests sent (not including retransmissions).
responsesReceived of type unsigned long long
Represents the total number of connectivity check responses received.
responsesSent of type unsigned long long
Represents the total number of connectivity check responses sent. Since we cannot distinguish connectivity check requests and consent requests, all responses are counted.
retransmissionsReceived of type unsigned long long
Represents the total number of connectivity check request retransmissions received. Retransmissions are defined as connectivity check requests with a TRANSACTION_TRANSMIT_COUNTER attribute where the "req" field is larger than 1, as defined in [[!RFC7982]].
retransmissionsSent of type unsigned long long
Represents the total number of connectivity check request retransmissions sent.
consentRequestsSent of type unsigned long long
Represents the total number of consent requests sent.
consentExpiredTimestamp of type DOMHighResTimeStamp
Represents the timestamp at which the latest valid STUN binding response expired,
as defined in [[!RFC7675]] section 5.1. If a valid STUN binding response has not
been made (responsesReceived is zero) or the latest one has not
expired this value must be undefined.
enum RTCStatsIceCandidatePairState {
"frozen",
"waiting",
"in-progress",
"failed",
"succeeded"
};
| Enumeration description | |
|---|---|
frozen
|
Defined in Section 5.7.4 of [[!RFC5245]]. |
waiting
|
Defined in Section 5.7.4 of [[!RFC5245]]. |
in-progress
|
Defined in Section 5.7.4 of [[!RFC5245]]. |
failed
|
Defined in Section 5.7.4 of [[!RFC5245]]. |
succeeded
|
Defined in Section 5.7.4 of [[!RFC5245]]. |
dictionary RTCCertificateStats : RTCStats {
DOMString fingerprint;
DOMString fingerprintAlgorithm;
DOMString base64Certificate;
DOMString issuerCertificateId;
};
fingerprint of type DOMString
The fingerprint of the certificate. Only use the fingerprint value as defined in Section 5 of [[!RFC4572]].
fingerprintAlgorithm of type DOMString
The hash function used to compute the certificate fingerprint. For instance, "sha-256".
base64Certificate of type DOMString
The DER-encoded base-64 representation of the certificate.
issuerCertificateId of type DOMString
The issuerCertificateId refers to the stats object that contains the next certificate in the certificate chain. If the current certificate is at the end of the chain (i.e. a self-signed certificate), this will not be set.
partial dictionary RTCIceCandidateStats {
boolean isRemote;
};
isRemote of type boolean
false indicates that this represents a local candidate;
true indicates that this represents a remote candidate.
partial dictionary RTCIceCandidatePairStats {
double totalRtt;
double currentRtt;
unsigned long long priority;
};
totalRtt
This field got renamed to "totalRoundTripTime" in Dec 2016.
currentRtt
This field got renamed to "currentRoundTripTime" in Dec 2016.
priority
This field got removed in Feb 2018, as it cannot be represented in 53 bits. It can be recalculated if needed as defined in [[RFC5245]] section 5.7.2.
partial dictionary RTCRTPStreamStats {
DOMString mediaType;
double averageRTCPInterval;
};
mediaType of type DOMString
This field got renamed to "kind" in Feb 2018.
averageRTCPInterval
This field got renamed to "averageRtcpInterval" in Jan 2018.
Consider the case where the user is experiencing bad sound and the application wants to determine if the cause of it is packet loss. The following example code might be used:
var baselineReport, currentReport;
var sender = pc.getSenders()[0];
sender.getStats().then(function (report) {
baselineReport = report;
})
.then(function() {
return new Promise(function(resolve) {
setTimeout(resolve, aBit); // ... wait a bit
});
})
.then(function() {
return sender.getStats();
})
.then(function (report) {
currentReport = report;
processStats();
})
.catch(function (error) {
console.log(error.toString());
});
function processStats() {
// compare the elements from the current report with the baseline
for (let now of currentReport.values()) {
if (now.type != "outbound-rtp")
continue;
// get the corresponding stats from the baseline report
let base = baselineReport.get(now.id);
if (base) {
remoteNow = currentReport[now.remoteId];
remoteBase = baselineReport[base.remoteId];
var packetsSent = now.packetsSent - base.packetsSent;
var packetsReceived = remoteNow.packetsReceived - remoteBase.packetsReceived;
// if intervalFractionLoss is > 0.3, we've probably found the culprit
var intervalFractionLoss = (packetsSent - packetsReceived) / packetsSent;
}
});
}
The data exposed by WebRTC Statistics include most of the media and network data also exposed by [[!GETUSERMEDIA]] and [[!WEBRTC]] - as such, all the privacy and security considerations of these specifications related to data exposure apply as well to this specifciation.
In addition, the properties exposed by RTCReceivedRtpStreamStats, RTCRemoteInboundRtpStreamStats, RTCSentRtpStreamStats, RTCOutboundRtpStreamStats, RTCRemoteOutboundRtpStreamStats, RTCIceCandidatePairStats, RTCTransportStats expose network-layer data not currently available to the JavaScript layer.
Beyond the risks associated with revealing IP addresses as discussed in the WebRTC 1.0 specification, some combination of the network properties uniquely exposed by this specification can be correlated with location.
For instance, the round-trip time exposed in RTCRemoteInboundRtpStreamStats can give some coarse indication on how far aparts the peers are located, and thus, if one of the peer's location is known, this may reveal information about the other peer.
When applied to isolated streams, media metrics may allow an application to infer some
characteristics of the isolated stream, such as if anyone is speaking (by watching the
audioLevel statistic).
The following stats are deemed to be sensitive, and MUST NOT be reported for an isolated media stream:
This section will be removed before publication. The entries are in reverse chronological order.
This list does not include infrastructure and minor editorials.
The editors wish to thank the Working Group chairs, Stefan Håkansson, and the Team Contact, Dominique Hazaël-Massieux, for their support. The editors would like to thank Bernard Aboba, Taylor Brandstetter, Henrik Boström, Jan-Ivar Bruaroey, Karthik Budigere, Cullen Jennings, and Lennart Schulte for their contributions to this specification.