[arm-allstar] developing voice packs for ASL/HamVoIP

[David McGough]

Remember, we're using Asterisk 1.4.x ---NOT a recent version!  Everything 
is 8KHz sampling!  I included the G.722 CODEC for compatibility with Cisco 
VoIP phones, not for use directly with app_rpt.

Also note that 8KHz sampling is "hard wired" into all the app_rpt related 
channel drivers. The DSP code in these drivers used no other rates. 
Further, that provides more audio bandwidth than narrow FM radio can 
utilize.

73, David KB4FXC



On Wed, 23 Oct 2019, "Patrick Perdue via ARM-allstar" wrote:

> I thought about using SLN (raw PCM.) Asterisk can take files at 48 kHz 
> 16-bit signed, and translate them to any codec, in the unlikely event 
> that you are using G722. Probably way overkill in this case, though.
> 
> Speaking of G722, is anyone using that on a public node? I'd like to try 
> that between two nodes. Anyway, I could convert to raw PCM as easily as 
> raw ULAW with SoX. At 8 kHz, it takes twice the space as ULAW, but with 
> very little benefit, as far as radio goes. ULAW is definitely a huge 
> improvement over GSM for... well... anything, really, but anything that 
> isn't GSM would take more work to implement on a HamVoip system, since 
> some scripts called from outside of Asterisk are hard-coded to GSM. It 
> would be pretty easy to write a script that recursively searches for 
> .gsm in *.pl and *.sh in /usr/local/sbin, I guess.
> 
> Oh, and that's another good reason to not use any containers. You can 
> splice raw data without worrying about pops and clicks from riff wav 
> headers and the like, even if you use a supported file format that 
> Asterisk likes within that container.
> 
> On 10/23/2019 7:16 PM, "David McGough via ARM-allstar" wrote:
> > Hi Danny,
> >
> > Remember that the .wav format is just a container. Many different CODECs
> > can be used in the .wav container, most of them incompatible with
> > asterisk. In addition, the files are somewhat larger and realistically not
> > easier to manage with sox, for asterisk use. The reason is that you've
> > still got to tell sox all the details about the CODEC to use, sample rate
> > (8KHz), etc.
> >
> > 73, David KB4FXC
> >
> >
> >
> > On Wed, 23 Oct 2019, "Danny K5CG via ARM-allstar" wrote:
> >
> >> If we're not concerned about disk space whynot use wav files. They play just fine and are easier to manipulate with tools like sox.
> > Danny
> > K5CG
> >
> >
> > _______________________________________________
> >
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> >
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>