Subject: RE: [Sipping] RE: draft-stein-great-00.txt

From: "Yaakov Stein" <[email-masked]>
Date: Mon, 10 Oct 2005 08:33:09 +0200

> Can someone please send me a reference to the "shock-absorber" 
> technique?  I'm not familiar with that.

It is described briefly in the draft.

I quote
   In jitter buffer based
   systems Incoming packets are not directly played out, but rather
   placed in a 'jitter buffer' and later played out at a constant rate.
   The jitter buffer is usually configured to be able to absorb the
   maximum expected PDV, and thus introduces a significant amount of
   delay.  In 'shock absorber' based systems packets are played out as
   they arrive, and when a packet is not yet available, a signal
   processing algorithm is employed to extrapolate based on previous
   packets, until such time as a packet arrives.  These systems
   introduce only minimal additional latency, but require considerably
   more computational power.

This is the basic idea, but there are numerous variations.

Y(J)S

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From: Greg Herlein <[email-masked]>
Date: Mon, 10 Oct 2005 04:34:54 -0700 (PDT)

> This is the basic idea, but there are numerous variations.

Interesting.  Can you reference other academic papers or books or 
descriptions?  Implementations?  Perhaps a few codecs that 
actually implement this?

I'm anxious to learn more about these kinds of systems. I've done 
VoIP and/or IPTV for 7+ years and never seen this kind of system, 
so I understandably am very intrigued.  I'd love to look at the 
code for a systme that actually implements this solution.

Greg