[arm-allstar] software update status

[Tim Sawyer]

David,

Sounds like you've found the root cause of this and have a fix is the works.

Excellent!

I think this same problem is happening with RTCM's as well. I does seem
less frequent or harder to detect by ear. That may have more to do with
using ACID on Intel Atom hardware than it does with RTCM's, don't know.

Is your fix only to simpleUSB, or is there a chance it will help RTCM's as
well?

On Mon, Aug 31, 2015 at 11:24 PM, David McGough <kb4fxc at inttek.net> wrote:

>
> Hi Bob,
>
> The variable audio delay issue is occasionally seen on PC-computer
> platforms, too, particularly with the simpleusb driver. This is NOT the
> audio delay that is unavoidable due to buffering as the audio samples pass
> through Asterisk. Nor is this issue related to the Asterisk jitter buffer,
> etc.
>
> Basically stated, the problem is that the input sample rate -dynamically-
> varies from the output sample rate. Depending on various factors, you may
> have too many samples, or too few, at any given moment. With the current
> code, the main issue seen is that too many output sound frames get queued,
> causing a frequently increasing in length input to output audio
> delay--sometimes with delays of maybe as much as one second (really
> annoying!). If there is an output buffer under-run, you hear a pop/click
> due to running out of samples.
>
> Initially, I suspected some kind of subtle bug in the simpleusb sound
> code. But, after experimentation, I've been able to easily duplicate this
> issue using my native ALSA stand-alone test software or even ALSA
> applications like arecord and aplay, etc.
>
> One solution to this problem is to use a dynamic buffer that effectively
> re-samples the audio, gently up-sampling or down-sampling, depending on
> the current trends for overrun or under-run.  I've got working software
> that accomplishes this now. And, it runs full-duplex beautifully for 24+
> hours with no change in audio delay and no logged clicks or pops.
>
> Hopefully, I'll get a few days time when I'm rested to focus on completing
> the integration of this code into simpleusb.  So far, I've had no time at
> all to complete this.
>
> But, hopefully soon.
>
> 73, David KB4FXC
>
>
>
> On Mon, 31 Aug 2015, kk6ecm wrote:
>
> > Couple of questions:
> >
> > 1) Is this audio delay the same as experienced with ACID?
> >
> > 2) What is the nature of the fix that reduces the delay?
> >
> > Thanks,
> > Bob
> > kk6ecm
> >
> > Sent from iPad
> >
> >
> > > On Aug 27, 2015, at 9:33 AM, David McGough <kb4fxc at inttek.net> wrote:
> > >
> > >
> > > Hi LaRoy,
> > >
> > > Progress has been slow in recent weeks, due primarily to family
> > > commitments that I've got. At this point, the update is waiting on me.
> > >
> > > I am hopeful to minimally have a bug-fix interim release soon. The big
> > > item on the list being resolution for the variable audio delay.
> > >
> > > I hope to have more details soon.
> > >
> > >
> > > 73, David KB4FXC
> > >
> > >
> > >
> > >> On Thu, 27 Aug 2015, LaRoy McCann wrote:
> > >>
> > >> Doug,
> > >> Just curious on how things are progressing with a new software update
> > >> for the PI2?
> > >>
> > >> Thanks,
> > >>
> > >> LaRoy McCann, K5TW
> > >>
> > >>
> > >>
> > >>
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-- 
--
Tim
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