Re: [tsvwg] [Ecn-sane] Comments on L4S drafts

[Dave Taht <[e-mail]>]

On Sat, Jun 15, 2019 at 10:44 AM Dave Taht <[e-mail]> wrote:
>
> On Fri, Jun 14, 2019 at 11:28 AM Holland, Jake <[e-mail]> wrote:
> >
> > Hi Ingemar,
> > (bcc: ecn-sane, to keep them apprised on the discussion).
> >
> > Thanks for chiming in on this.  A few comments inline:
> >
> > On 2019-06-08, 12:46, "Ingemar Johansson S" <[e-mail]> wrote:
>
> > > I see many applications that can benefit greatly from L4S, besides AR/VR,

I over reacted to the second part of this sentence. AR/VR - assuming
it's over a reliable short RTT isochronous transport, can benefit from
 L4S-style techniques.

> > > there is also an increased interest in the deployment of remote control
> > > capabilities for vehicles such as cars, trucks and drones, all of which
> > > require low latency video streaming.

but not this.

> This is a poor example of a use case for l4s. The link rates in these
> cases are *wildly variable*.
>
> - in the case of a realtime command and control video stream on cars,
> trucks, drones, uav or rockets, you *want* packet loss, you want the
> most current frame or fragments thereof as closely tied to actual
> event as possible. You want to drop from the head, not the tail of the
> queue, when the rate changes, so the most
> current data is available to the operator.
>
> See any launch video from spacex for this.
>
> You also want backpressure or preferably an out of band signal to the
> encoder (if you have one) so it
> drops the encoding resolution down to the data rate ASAP, if you
> exceed the capacity, while holding the video frame rate steady.
>
> And you want to be running well below the presently observed capacity
> of the link at all times, because it's precisely when things are going
> south that you want the most data, especially if you are also
> multiplexing control traffic over the same link.
>
> --
>
> Dave Täht
> CTO, TekLibre, LLC
> http://www.teklibre.com
> Tel: [phone]



-- 

Dave Täht
CTO, TekLibre, LLC
http://www.teklibre.com
Tel: [phone]