[IP] more on Lingo v Vonage

[David Farber <dave@farber.net>]

Is there or will there be a skype for MAC OS X.


Begin forwarded message:

From: Brad Templeton <btm@templetons.com>
Date: July 24, 2004 1:00:37 AM EDT
To: David Farber <dave@farber.net>
Cc: mo@ccr.org
Subject: Re: [IP] more on Lingo v Vonage

> Vonage uses the standard PCM audio codec by default because
> people prefer it.
>
> a Vonage subscriber can go to his account management page and
> pick a more aggressive codec if he wishes.  this is a pretty
> straightforward quality-performance tradeoff and different
> people are willing to make it diffent ways.
>
> there's a *lot* of activity around CPE and people
> can expect that to evolve pretty quickly.


I am highly curious to see how people will react to different codecs.

I have advocated for some time that VoIP companies should try to
put "better than PSTN (G.711)" codecs in their equipment, so that
well people have a pure VoIP call, they always go away thinking
that it was a lot nicer, HDTV vs. NTSC SDTV.

Skype has done this, using the Global IP Sound high frequency response
codec by default in Skype.  As such, I have been pushing people
doing calls with me to use Skype if they have it.

Codecs like the one in Skype actually use less bandwidth than G711
even though they provide much better voice quality.  There is
a tradeoff, however.   Data compression requires you gather up
enough sound to do decent data compression into a packet, and that
adds more latency.  Unfortunately, the curse of all VoIP calls that
go over the broad internet has been inferior latency to typical
Tedium-based PSTN calls over the same distance.  Increasing your
compression (even to get better bandwidth) bumps that a little bit.

You could of course do low-compression, high-frequency-range codecs,
but nobody is quite up for the bandwidth needed for those.

When I do Skype calls, I am highly curious as to whether people
find the improved sound quality simply an incremental improvement,
or if it's one of those sea-change differnces in which, after you
have it, you are reluctant to go back.  No firm answer to that
yet.


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