W3C home > Mailing lists > Public > public-webrtc@w3.org > May 2013

Stats variables - some more input

From: Harald Alvestrand <harald@alvestrand.no>
Date: Mon, 27 May 2013 15:36:37 +0200
Message-ID: <51A36165.7030609@alvestrand.no>
To: "public-webrtc@w3.org" <public-webrtc@w3.org>
I'm continuing with the process of designing stats variables that make 
sense and are useful.
My current draft is reproduced below. Comments welcome!

One question that arose about audio volume representation: It's hairy.
Especially it's hairy to define volume in a way that makes sense when 
you don't know the sampling interval (because this is a polling 
interface), and you don't want to give undue importance to the last 
tenth of a before the sample. Or perhaps you do - it might be app dependent.

One suggestion made internally: Just report the cumulative audio energy 
(sum of audio energy over time) instead. Then people can transform that 
as they will.

Thoughts on this?
For now, the proposal contains a conventional "audio level" variable.
For the rest:

Root of hierarchy:

dictionary RTCStats {
DOMHiResTimeStamp timestamp;
RTCStatsType type;
DOMString id;

All SSRCs:

dictionary RTCRTPStreamStats : RTCStats {
DOMString ssrc;
DOMString remoteId;
// New stuff:
DOMString mediaTrackId;
DOMString transportId;
DOMString codecId;

Note the convention that names ending in “Id” are identifiers of other 
stats objects.
Directed SSRCs:

dictionary RTCInboundRTPStreamStats : RTCRTPStreamStats {
unsigned long packetsReceived;
unsigned long bytesReceived;
// In addition to current spec:
float jitter;

dictionary RTCOutboundRTPStreamStats : RTCRTPStreamStats {
unsigned long packetsSent;
unsigned long bytesSent;

Representing MediaStreamTracks:

dictionary RTCMediaStreamTrackStats : RTCStats {
DOMString trackIdentifier; // track.id property
boolean remoteSource;
sequence<DOMString> ssrcIds;
// Only makes sense for audio
unsigned int audioLevel;
// Only makes sense for video
unsigned int frameWidth;
unsigned int frameHeight;
unsigned float framesPerSecond; // The nominal FPS value
unsigned int framesSent;
unsigned int framesReceived; // Only makes sense for remoteSource=true
unsigned int framesDecoded;
int firs;

dictionary MediaStream : RTCStats {
DOMString streamIdentifier; // stream.id property
sequence<DOMString> trackIds; // Note: This is the id of the stats 
object, not the track.id

Representing transports:

dictionary RTCTransport: RTCStats {
unsigned long bytesSent;
unsigned long bytesReceived;

dictionary RTCIceComponentStats : RTCStats {
DOMString transportId;
int component;
unsigned long bytesSent;
unsigned long bytesReceived;
bool activeConnection;

dictionary RTCIceCandidatePairStats : RTCStats {
DOMString componentId;
DOMString localCandidateId;
DOMString remoteCandidateId;
boolean writable; // Has gotten ACK to an ICE request
boolean readable; // Has gotten a valid incoming ICE request

dictionary RTCIceCandidate : RTCStats {
DOMString ipAddress;
int portNumber;
// More ICE-related info goes here.

dictionary RTCCodec : RTCStats {
unsigned int payloadType; // As used in RTP encoding.
DOMString codec; // video/vp8 or equivalent
unsigned int clockRate;
unsigned int channels; // 2 for stereo, missing for most other cases.
DOMString parameters; // From SDP description line
Received on Monday, 27 May 2013 13:37:13 UTC

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