[App_rpt-users] Codec Negotiation

Fri Feb 9 05:32:38 UTC 2018

 Hi Benjamin,

I agree 100% about the small bandwidth savings not making a difference when
you have great signal, however; that doesn't mean that one codec won't
perform better than another given certain network conditions. I will do
some more testing, but my first initial tests were that ilbc sounded much
better than the others when I had 1 bar of LTE. When there's heavy network
degradation throughput suffers and in certain situations you will see
better results with a lower bandwidth codec.

Think about it, cellular is now VOIP over LTE. And although it doesn't go
through double NAT and has QoS and all that jazz, there's no reason I
shouldn't be able to use AllStar without issues when I have good LTE signal
(i.e. 2 bars or more). Skype, Google Voice, FaceTime Audio, Facebook Audio,
and even Echolink doesn't seem to have this problem on my same commute with
the same network conditions, and neither should AllStar. I mean, I can sit
here at home and stream HD video with no issues on my iPhone. One thing I
will test is connecting via AllStar via Echolink. I'm not sure what codec
is used with AllStar connecting via Echolink.

Verizon is using IPv6 and they are also giving out IPv4 via CGN, which is
what I'm seeing on my phone/hotspot. This is a double NAT, yes, but that's
no excuse either. I could also setup a VPN but then there's even more
complexity and in some cases can make performance worse.

Come to think of it, I hear Grady talking a good bit on his AllStar micro
node through his cellular hotspot while driving and his sounds great. I'll
like to know what cellular service he has and what codec his micro node is
using.

Pretty much off topic, but I do use our local repeaters via RF. When I get
out of range is mainly when I use my hotspot. But I use it to connect back
to our local repeater, when if I didn't have a hotspot I wouldn't be able
to use it. So the way I see it, I get to use the repeater more than if I
didn't have the node, because now all I need is Internet access anywhere in
the world. So I guess I look at it completely different. And as you already
know, it also allows me to connect to Columbus and join in on the AllStar
Tech Net. If I didn't have my node and hotspot while mobile, then that's
less use those repeaters would see.

But for what it's worth I appreciate the time you spent to think about it
and white up your reply.

73 for now.
Will, KE4IAJ

On Thu, Feb 8, 2018 at 11:47 PM, Benjamin Naber <Benjamin at project23d.com>
wrote:

> Will et al:
>
> Read this message please.
>
> Given the bandwidth availability of LTE and even remaining 3G, from
> cellular providers, going from 88kpbs to 18kpbs is NOT going to make a
> difference. While many seem to think this is true, it is simply not the
> case. Even with poor signal, but able to maintain a cellular data
> connection, the bandwidth is still going to be hundreds of kbits. Just
> not [UDP] reliable.
>
> Cellular data providers don't really care about UDP, their main concern
> is TCP reliability. Many streaming services are now TCP, hence lagging
> and slow to buffer video and voice streams, but little to zero
> "noticeable" drop-outs.
>
> I have several friends that use cellular hotspots, with their radio
> hotspots and be it DMR, allstar, echostink, it's very unreliable. The
> bigger the city the more unreliable it seems. My experience with
> cellular data is the same.
>
> What I am seeing now, and have a theory is this:
> Verzion and ATT now use IPv6 for their cellular data subscribers. No
> cellphone in their US networks get IPv4 any more. In the middle of last
> year, Verizon started issuing ONLY IPv6 addresses to their subscribers.
>
> This means that any IPv4 address must be routed through their limited
> placement, subscriber internet access gateway (overloaded) and then
> through another IPv6 to IPv4 gateway. These IPv6 <-> IPv4 gateways are
> getting overloaded, causes the data unreliability issues.
>
> How to solve this? Use the open repeaters in the area you are in!!!
>
> radio hotspots are nice, but if everyone is using a hotspot, then why
> should repeaters exist? Then, that one time, when some natural disaster
> takes out cellular, your cellular data connected radio hotspot is NOT
> going to work, but I am pretty sure the amateur radio repeaters in the
> area will - even if the internet at the repeater site doesn't work. If
> there are any repeaters left when that happens.
>
> What does not get used, does not get maintained.
>
> ~Benjamin, KB9LFZ
>
>
> On Thu, 2018-02-08 at 20:38 -0500, Will Bashlor wrote:
> > Hi List,
> >
> > Ok, so I have a portable node and it works great at home but on the
> > road using my iPhone hotspot with Verizon it's quite jittery and
> > doesn't sound very good, even when I have 2 or 3 bars. I can connect
> > to the same node using echolink and it works fine even with 1 to 2
> > bars.
> >
> > I'm using the hamvoip image without any codec changes and I notice it
> > connects to our local repeater hamvoip node with g726aal2 which makes
> > sense because  g726aal2 is first in [general] which I believe
> > controls outbound connections.
> >
> > So I wanted to see what I sounded like so I connected to 40894 so I
> > could hear my own voice. It connected using ulaw for some reason. The
> > only way I could get it to change was to comment out the codecs I
> > didn't want to use in [general]. Apparently it doesn't negotiate how
> > I think it does.
> >
> > On ulaw and  g726aal2 it sounded pretty terrible. gsm was better but
> > it was still broken up. I wanted to try ilbc but codec negotiation
> > failed which I'm sure means that 40894 doesn't allow ilbc.
> >
> > I then connected successfully to our local repeater node with ilbc
> > and it sounded just fine, even with one bar, but I need to test
> > more...
> >
> > Is this anyone else's experience with using hotspots?
> >
> > I've modified the codec under [genera] to the below, which the way I
> > understand is for outgoing connections. And the codec order is the
> > order of attempted negotiation. I ordered them on my portable node in
> > order of least bandwidth to greatest.
> >
> > So with that said, when I connect to my local node, which allows
> > ilbc, why does it negotiate to g726aal2?
> >
> > And how can I setup iax.conf so it always connects using the lowest
> > bandwidth codec that the other side allows?
> >
> > allow=ilbc
> > allow=gsm
> > allow=g726aal2
> > allow=ulaw
> >
> > 73,
> >
> > Will, KE4IAJ
> > _______________________________________________
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