[arm-allstar] codecs

[Dan Keizer]

Thanks guys - appreciate your feedback on your experiences.

Interesting : g726 would be using about 40Kbps per connection. iLBC would
use about 15Kbps and G729 about 8Kbps, codec2 would use about 2.4Kbps.
While our available bandwidth is normally quite good - I'm also looking at
sites that may have more latency and being in vicinity of some high power
broadcast stations, ensuring a good remote wifi connection with good RF
shielding will be important for these.  While the codec2 project aims to
have decent SSB-like signal quality, it would no where come close to good
quality FM - but may be of value in some situations.

The default installed codecs on the hamvoip project are:
        INT    BINARY        HEX   TYPE       NAME   DESC
--------------------------------------------------------------------------------
          1 (1 <<  0)      (0x1)  audio       g723   (G.723.1)
          2 (1 <<  1)      (0x2)  audio        gsm   (GSM)
          4 (1 <<  2)      (0x4)  audio       ulaw   (G.711 u-law)
          8 (1 <<  3)      (0x8)  audio       alaw   (G.711 A-law)
         16 (1 <<  4)     (0x10)  audio   g726aal2   (G.726 AAL2)
         32 (1 <<  5)     (0x20)  audio      adpcm   (ADPCM)
         64 (1 <<  6)     (0x40)  audio       slin   (16 bit Signed Linear
PCM)
        128 (1 <<  7)     (0x80)  audio      lpc10   (LPC10)
        256 (1 <<  8)    (0x100)  audio       g729   (G.729A)
        512 (1 <<  9)    (0x200)  audio      speex   (SpeeX)
       1024 (1 << 10)    (0x400)  audio       ilbc   (iLBC)
       2048 (1 << 11)    (0x800)  audio       g726   (G.726 RFC3551)
       4096 (1 << 12)   (0x1000)  audio       g722   (G722)

I think I'll have to give these a try and test them on the RF side as well.
(I used g729 as a standard for all my prior asterisk configs).  Will do
some tests, thanks.

And, just so I know, what's the preferred method on recompilation -
-downloading asterisk and rebuilding -- assuming compiling fresh from
source, what's the usual time frame for recompilation on these machines
these days?  Do you have source that you have used or just the images?

73, Dan ve4drk

On Sun, May 7, 2017 at 5:37 AM, David McGough <kb4fxc at inttek.net> wrote:

>
> Hi Dan,
>
> I added CODEC2 to Asterisk/AllStar several years ago as an experiment.
> While IMHO the audio quality was better than that heard on systems using
> the IMBE/AMBE CODECs, the quality was still *FAR* below iLBC (and G729,
> which is now freely available, since the patent expired a few months ago).
>
> And, I found that once IAX2 protocol overhead got added in, the network
> bandwidth savings over using iLBC wasn't as impressive as I had hoped.
>
> So, CODEC2 sat unused; the only obvious choice for using it being to avoid
> transcoding if CODEC2 audio came from another source---like from an HF
> MODEM using the FreeDV software or similar.
>
> Anyhow, this code pre-dated the hamvoip project and was running on a
> hybrid x86 ACID box. That code isn't in the current V1.5 release; however
> it is still on an that old ACID system. I've never tried it on an ARM
> chip.
>
> 73, David KB4FXC
>
>
>
> On Sat, 6 May 2017, "Dan Keizer via arm-allstar" wrote:
>
> > Curious to know if anyone has some experience with codec2 with allstar
> > linking?
> >
> > I'd certainly like to minimize the bandwidth - and use ham developed tech
> > at the same time.
> >
> > Speaking of such - since we want to hook up a number of nodes together,
> we
> > are establishing a local "super node" on a high availability server
> located
> > only a couple of hops from our 2.3GHz network.  Internet bandwidth
> provided
> > by a supporting ham via a 24GHz air fiber.  And
> rackspace/hosting/internet
> > for this node provided by another local ham.
> > I'm thinking a stock install of allstarlink would work well for an
> instance
> > such as this.
> > Any caveats or experience with such?
> >
> > 73, Dan ve4drk
> > _______________________________________________
> >
> > arm-allstar mailing list
> > arm-allstar at hamvoip.org
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> >
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> >
>
>