[h323plus] Dynamic Bandwidth Management!!

Robert Jongbloed robert.jongbloed at bigpond.com
Mon Jan 21 16:23:00 EST 2008


The other possibility is that he is talking about "in call" bandwidth
management, specifically the H.245 FlowControlCommand/FlowControlIndication
messages which can be used to control the bandwidth of a specific codec. For
audio it is not hugely useful unless you have something like GSM-AMR or
G.722.2 (aka GSM-AMR wideband) which have a few bit rate options, but it can
be really useful for video as most codecs have a wide range of bit rates.

 

Both H323plus and OPAL have "bits and pieces" of support for this, but no
one has ever really looked closely at it to give it a really good debug. At
least no one out there that has admitted to it! L

 

 

As another throw away comment: the rise in available bit rate will hopefully
make wide band codecs such as Speex-wb and G.722.2 more popular. I've used
them in other environments and the quality is noticeably better, and as
voice quality is one of the biggest complaints people have with VoIP, it can
only help!

 

 

Robert Jongbloed

OPAL/OpenH323 Architect and Co-founder.

 

From: h323plus-bounces at lists.packetizer.com
[mailto:h323plus-bounces at lists.packetizer.com] On Behalf Of Paul E. Jones
Sent: Tuesday, 22 January 2008 1:00 AM
To: Frank Fischer; h323plus at lists.packetizer.com
Subject: Re: [h323plus] Dynamic Bandwidth Management!!

 

Frank,

 

Ah, OK.  That makes sense.

 

>From an H.323 perspective, this kind of thing is almost doable, but no
remote device would be obliged to make adjustments.  One could send a
Request Mode message and the receiver could politely refuse.  (Likewise, a
SIP device could refuse an offer to propose changes to established media
flows.)  The other issue is knowing whether or not bandwidth needs to be
adjusted or can be adjusted.  One might say that bandwidth could increase,
because there is no observed packet loss.  But, perhaps an increase in
bandwidth might then disrupt some other service (e.g., other voice calls in
progress).  So, then perhaps the bandwidth might be decreased to compensate.
This then leads one in a vicious cycle of bandwidth adjustments up and down.

 

And, as you rightfully point out, available bandwidth is constantly rising
and it will continue, since people want to utilize services that require
more bandwidth and want to use even more services simultaneously.  The
80Kbps voice call is really very little compared to the Gbps of bandwidth
most broadband customers have today.  Still, there are bandwidth-constrained
locations, but the best recommendation I could make is to simply select a
lower bit-rate codec and use that.  Skype, for example, always uses G.729
for calls to PSTN gateways and the sound quality seems very good to me.

 

Paul

----- Original Message ----- 

From: Frank Fischer <mailto:frank.fischer at digitalnomads.ch>  

To: h323plus at lists.packetizer.com 

Sent: Monday, January 21, 2008 8:42 AM

Subject: Re: [h323plus] Dynamic Bandwidth Management!!

 

Hi

 

i think he means the abillity to dynamically change the codec during
transmission to follow any changes in available bandwith. I.e. when starting
with g.711 and the available bandwith drops to 80kbits then i.e. g.729
could be negotiated on the fly. 

 

Actually a very nice feature but probably not very easy to implement and
more important, getting less and lesser important since bandwiths are
constently increasing almost all over the world....

 

Frank

 

 


  _____  


From: h323plus-bounces at lists.packetizer.com
[mailto:h323plus-bounces at lists.packetizer.com] On Behalf Of Paul E. Jones
Sent: Monday, January 21, 2008 2:33 PM
To: Abhishek Rohilla; h323plus at lists.packetizer.com
Subject: Re: [h323plus] Dynamic Bandwidth Management!!

Abhishek,

 

H.323 Plus aside, what do you mean by "dynamic bandwidth management"?

 

Paul

 

----- Original Message ----- 

From: Abhishek Rohilla <mailto:abhishekrohilla at gmail.com>  

To: h323plus at lists.packetizer.com 

Sent: Monday, January 21, 2008 4:44 AM

Subject: [h323plus] Dynamic Bandwidth Management!!

 

Hi 

Someone please help me with this.
I wanted to know does H323+ does dynamic bandwidth management and mange the
codec bit rate accordingly?

How is it  done.?? Where can I find the code in RTP files in H323+ where
bandwidth info is calculated? 

Thanks




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