Re: [Dart] I-D Action: draft-york-dart-dscp-rtp-00.txt

["Black, David" <[e-mail]>]

> Yes - except that every time it's used in draft-york, including in the
> place it is defined, it means "RTP packet stream". If you are trying to
> use it for the stuff that's inside the RTP packets instead of the RTP
> packet streams, the definition needs to say so.

Ok, will try to clarify - I'll put this on the list of things to do in
the -01 version, including making sure it lines up well with the
rtcweb-qos draft.

> "Media source" is the term I think you're thinking of in -taxonomy- that
> corresponds more closely to the term - the complexifier is all the cases
> where a single media source is carried over multiple packet streams.

IMHO, "Media source" sounds like the sender, not what is sent.  MediaStream
seems to be a term for that what is sent that could be carried as multiple
RTP packet streams.

Thanks,
--David


> -----Original Message-----
> From: Dart [mailto:[e-mail]] On Behalf Of Harald Alvestrand
> Sent: Wednesday, June 11, 2014 10:22 AM
> To: [e-mail]
> Subject: Re: [Dart] I-D Action: draft-york-dart-dscp-rtp-00.txt
> 
> On 06/11/2014 04:10 PM, Black, David wrote:
> > Harald,
> >
> >> Careful - "RTP packet stream" is one of those concepts that can be
> >> meaningless without citing a specific definition.
> > +1
> >
> >> draft-ietf-avtext-rtp-grouping-taxonomy is probably the best reference
> >> at the moment. It says this about "Packet stream":
> > Thank you for the pointer, we'll be happy to cite and use that definition.
> >
> >>      For the purposes of this draft, the term "media flow" refers to a
> >>      sequence of packets that is transmitted as a single RTP packet
> >>      stream.
> >>
> >> The term "media flow" doesn't sound to me like a good term to use for this
> concept.
> >> Would the authors be willing to consider switching to "packet stream"?
> > Speaking only for myself, I don't think so, because there are two
> > different concepts involved - IMHO, this draft needs two terms to refer to:
> >
> > 	a) What the application sends.
> > 	b) How RTP carries that traffic.
> >
> > "RTP packet stream" is clearly the right RTP term for the latter, and the
> > draft was written that way.  I would've liked to have used "media stream"
> > for the former, but W3C has defined MediaStream to not be a single stream
> > of media (go figure ...).  "media flow" seemed to be as good a term as
> > any for that concept, and "media flow" is already used for that concept
> > in draft-ietf-tsvwg-rtcweb-qos (i.e., it was not invented for this draft).
> Yes - except that every time it's used in draft-york, including in the
> place it is defined, it means "RTP packet stream". If you are trying to
> use it for the stuff that's inside the RTP packets instead of the RTP
> packet streams, the definition needs to say so.
> 
> "Media source" is the term I think you're thinking of in -taxonomy- that
> corresponds more closely to the term - the complexifier is all the cases
> where a single media source is carried over multiple packet streams.
> 
> >
> > If you have an alternative term, please suggest it ... and then the authors
> > of any other draft that uses "media flow" (starting w/the rtcweb-qos draft)
> > will have to go make corresponding changes.
> >
> > Thanks,
> > --David
> >
> >> -----Original Message-----
> >> From: Dart [mailto:[e-mail]] On Behalf Of Harald Alvestrand
> >> Sent: Wednesday, June 11, 2014 7:09 AM
> >> To: [e-mail]
> >> Subject: Re: [Dart] I-D Action: draft-york-dart-dscp-rtp-00.txt
> >>
> >> On 06/10/2014 09:44 PM, Black, David wrote:
> >>> Hi Ruediger,
> >>>
> >>>> thanks, your team created a well written draft.
> >>> Great - thanks for taking a look.
> >>>
> >>>> If a MediaStream is carried in a RTP session, the text may also
> explicitely
> >>>> say that (it says MediaStreamTrack == media flow, which is carried in an
> >>>> individual RTP packet stream)
> >>> As I read Section 11 of draft-ietf-rtcweb-rtp-usage-15, for RTCWEB,
> >>> that would happen only when the MediaStream contains exactly one
> >>> MediaStreamTrack.  The use of these terms in bullet item 1 in section 2
> >>> is intended to be specific to RTCWEB, but we could add text elsewhere to
> >>> point out that non-RTCWEB usage of MediaStreams could use an RTP packet
> >>> stream for each Media Stream, independent of how many MediaStreamTracks
> >>> each MediaStream contains.
> >>>
> >>> Could you suggest a reference that could be cited for usage of an RTP
> >>> packet stream for each MediaStream independent of how many
> >>> MediaStreamTracks each MediaStream contains?
> >> Careful - "RTP packet stream" is one of those concepts that can be
> >> meaningless without citing a specific definition.
> >>
> >> draft-ietf-avtext-rtp-grouping-taxonomy is probably the best reference
> >> at the moment. It says this about "Packet stream":
> >>
> >> 2.1.10.  Packet Stream
> >>
> >>      A stream of RTP packets containing media data, source or redundant.
> >>      The Packet Stream is identified by an SSRC belonging to a particular
> >>      RTP session.  The RTP session is identified as discussed in
> >>      Section 2.2.2.
> >>
> >> Under this definition, it's impossible to put more than one
> >> MediaStreamTrack into a packet stream.
> >> In a lot of cases (FEC, redundancy, SVC, simulcast), there will be
> >> multiple RTP packet streams associated with one MediaStreamTrack.
> >>
> >> The term is used only once in the draft, but unfortunately defines a new
> >> term to mean the same thing:
> >>
> >>      The most common protocol used for real time media is the Real-Time
> >>      Transport Protocol (RTP)[RFC3550].  RTP defines the mechanism by
> >>      which real-time data is transmitted between hosts on the Internet.
> >>      With most applications, a single media type (e.g., audio) is
> >>      transmitted within a single RTP session.  However, it is possible to
> >>      transmit multiple, distinct media flows over the same RTP session as
> >>      individual RTP packet streams.  This is referred to as RTP
> >>      multiplexing.
> >>
> >>      For the purposes of this draft, the term "media flow" refers to a
> >>      sequence of packets that is transmitted as a single RTP packet
> >>      stream.
> >>
> >> The term "media flow" doesn't sound to me like a good term to use for
> >> this concept.
> >> Would the authors be willing to consider switching to "packet stream"?
> >>
> >>
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