Re: [RE] Time sensitivities in ResE. Part 2: Latency
Michael;
You certainly get this right. Even if you start with 10-15 ms total system
delay budget then it still brings you down to maximum 2 ms network delay.
Best regards,
Alexei Beliaev
Gibson Labs
408-313-2665
----- Original Message -----
From: "Michael Johas Teener" <mikejt@BROADCOM.COM>
To: <STDS-802-3-RE@LISTSERV.IEEE.ORG>
Sent: Tuesday, April 12, 2005 5:22 PM
Subject: [RE] Time sensitivities in ResE. Part 2: Latency
> Once again, there are several reasons why latency matters in a
> media-streaming network.
>
> 1) Control response ... in a normal CE system, the latency of most
> importance is that between the time a consumer presses a button the remote
> control and the time the appropriate response is perceived by that same
> consumer. Response times of current consumer devices is on the order of
> 0.2
> to 0.5 sec. Some devices take longer, but are disliked (controls on an
> airplane entertainment system are typically pretty awful ... try them
> sometime). Unfortunately, much of the response time is consumed by the CE
> devices themselves, and any significant addition caused by the network
> would
> be unacceptable ... so let's say that the network should hold control
> latency to less than 100ms. Not too bad.
>
> 2) Perceptual feedback ... in system where the network is part of a
> musical
> instrument or gaming feedback, the requirements are much more severe.
> Average people start noticing problems at 8-10ms, and some professionals
> much sooner. As a network latency, this is not much of a problem, but the
> network isn't the only consumer of latency: in a typical system, the
> keyboard or guitar uses some, the audio processor (mixer/effects) uses
> some,
> and the amplifier uses some ... Alexei described this process in SG
> presentations some time ago, and came up with the 2ms figure for maximum
> network transit delay (did I get that right, Alexei?).
>
> This last one is particularly significant, since this latency figure is
> absolute, not statistical (any late data will cause glitches in the sound
> since we can't do much buffering here).
>
> --
> ---------------------------------------------------------------
> Michael D. Johas Teener < mikejt@broadcom.com
> office +1-408-922-7542 cell +1-831-247-9666 fax +1-831-480-5845
> http://public.xdi.org/=Michael.Johas.Teener - PGP ID 0x3179D202
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