[arm-allstar] Workaround for variable audio delay

[David McGough]

Hi LaRoy,

Yes, using usbradio is an option over simpleusb for resolving the variable
audio delay. As you have found, usbradio does work in the hamvoip release.  
And, usbradio can be used, if you're will to put up with a extra audio
artifacts here and there--I expect this noise is easy for me to hear,
since I've become accustom to listening for these artifacts during
software development and tuning...But, usbradio IS indeed usable.

As for reported CPU use differences, I expect this is mainly due to -all-
the reporting software and Linux Kernel found in the hamvoip release being
more recent than the equivalents included in the Debian version....YES,
that's correct: the hamvoip release uses a NEWER kernel, libraries, 
etc., even though it was released maybe 6 months earlier!  This is the 
advantage you get by using the Arch disto: it is truly (b)leading edge. 
Since the RPi2 device drivers have been rapidly evolving, (b)leading edge 
is typically a good thing...

Also, there is nothing wrong with disabling unused Asterisk modules in 
hamvoip release, similar as found in the Debian version--this -might- 
provide a small performance boost. It's worth nothing that these modules 
are multi-threaded and on the RPi2, there are four parallel cores. So, I 
expect any performance gain to be marginal, likely not even noticeable 
(but, I welcome someone to prove me wrong about this!!!).

Anyhow, as has been mentioned on the e-mail list, there is already a beta
simpleusb driver available that resolves the variable audio delay. It will
work ONLY with the stock hamvoip RPi2 1.0 release and is available on a
limited basis to those who wish to be Guinea Pigs....AH, I MEAN -beta
testers- LOL.  (Please contact off list for more info).

73, David KB4FXC



On Mon, 18 Jan 2016, LaRoy McCann wrote:

> I know there is a fix for the variable audio delay in testing and I look 
> forward to it being released.
> 
> In the meantime....
> I have been playing around and I think I have found a workaround for the 
> problem.
> At least it works for me.
> 
> I know the general rule of thumb is to use simpleusb instead of radiousb 
> because it puts less load on the cpu.
> I noticed in the config file for radiousb that you can still use the 
> hardwired inputs for cor and ctcss.
> Well, I decided to try radiousb to see what would happen.
> 
> I am using RP2 and only one full duplex repeater on each system.
> I have two systems that are linked together full time via the internet.
> One is running Arm Allstar image and the other is running DIAL image.
> 
> Arm Allstar Image:
>    What I have done is switched to using radiousb instead of simpleusb.
>    I use the hardwired input for cor.  (carrierfrom=usb)
>    I also use the hardwired input for ctcss.  (ctcssfrom=usb)
> 
> DIAL Image:
>    What I have done is switched to using radiousb instead of simpleusb.
>    I use the hardwired input for cor.  (carrierfrom=usb)
>    I use dsp for ctcss.  (ctcssfrom=dsp)
> 
> I am actually using dsp on the DIAL image for ctcss.  I thought I would 
> try this since I did not have a tone board on this repeater yet.
> It seems to work well decoding the ctcss.
> 
> 
> I know top is a different version between the two systems but on DIAL 
> the cpu load only runs about 3.6% cpu compaired to Arm Allstar which can 
> run around 25-26% cpu.
> It's hard to tell on Arm Allstar because top breaks down each cpu usage 
> where DIAL's version only shows the total cpu usage.
> 
> I noticed that on DIAL all modules are not loaded by default.  This 
> probably contributes to less of a load on the cpu.
> 
> 
> I have been running the DIAL system this way for about a week and the 
> Arm Allstar system since yesterday.
> It seems to have cured the variable audio delay issues for me.
> I do not hear any dropped or choppy audio.
> 
> 
> LaRoy McCann, K5TW
> 
> 
> 
> 
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> 
> 
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