[arm-allstar] [Spam?] Re: excessive audio delay problem -- a solution is coming
LaRoy McCann
lmccann at dtisp.com
Tue Apr 21 09:03:47 EST 2015
This is great news. Looking forward to this being released.
Also, with what Tim mentioned about the power saving mode causing some
issues,
maybe they could be disabled in the archlinux kernel as well.
With the continued code re-writes and kernel tweaking, his board might
really become a "power house". lol
Thanks for the info and keep us updated on the progress.
LaRoy McCann, K5TW
On 4/21/2015 3:33 AM, David McGough wrote:
> Hi Everyone,
>
> As many are noticing, there is a variable audio delay with the RPi2's and
> it seems more pronounced than the BBB. This issue can be present on the
> BBB's (and even PC's, unfortunately) as well, but, for the most part, it's
> better "hidden" than on the RPi2's.
>
> The RPi2, without -ANY- doubt, is the preferred board to go with at this
> point for new purchases--it solves a host of inconveniences that lurk on
> the BBB's (I won't go into all the details here). And, the RPi2 is much,
> MUCH faster, overall. However, one chief way is achieves speed is via
> parallel processing (multiple CPU cores), which adds its own new
> complexities.
>
> Over many weeks now I've been working on a new, native ALSA audio driver
> (and related telemetry handler) for AllStar and I've made a great deal of
> progress. To say this has been an eye-opening experience is the
> understatement of 2015! I've been amazed how difficult it is to -reliably-
> accomplish something so seemingly simple as echoing full-duplex audio from
> a microphone back to a headset, using a USB FOB!
>
> I'll mention that, while FAR from complete, my "test" software is running
> right here beside me and has been running full-duplex (like a repeater
> "keyed up continuously") for the last 18 hours straight. During that time,
> I've logged no audio buffer underruns or overruns (AKA: pops and clicks),
> and the audio driver has -maintained- consistent, predictable latency the
> whole 18 hours.
>
> I'll also mention that one of the design goals of this new software is a
> high-performance DSP subsystem; again more details about this later.
>
> So, a solution is in progress!
>
>
> 73, David KB4FXC
>
>
>
>
> On Mon, 20 Apr 2015, LaRoy McCann wrote:
>
>> No doubt it will introduce delays into the system.
>>
>> I am fairly new to using allstar. My first experience was with the bbb
>> and it did not have the broadcast delay like the Pi2 does.
>> Granted you hear a delay between input and output of the repeater using
>> either bbb or PI2.
>>
>> Does this mean the Pi2 is actually that much slower?
>> Maybe the software is not taking advantage of the multi-core processors yet.
>>
>> Don't get wrong, I think this is a great system and we are changing out
>> hardware controllers for Allstar.
>> My hat goes off to everyone that has made this type of system possible.
>>
>> LaRoy McCann, K5TW
>>
>>
>> On 4/20/2015 1:55 PM, Cole Cunningham wrote:
>>> Isn’t this type of delay inevitable when digitizing and then
>>> converting back to analog? Flat panel TV’s have all sorts of delay,
>>> noticable if you see the same programming source on two different
>>> capability or model sets.
>>>
>>> I have a BBB set up running a remote base into a local repeater and
>>> when I compare talking into the BBB via the Allstar web transceiver
>>> and what I hear on the repeater, there’s a BIG delay. 100’s of
>>> milliseconds. Same when listening to the repeater direct and also via
>>> the computer.
>>>
>>> AFAIK the only solution is processing speed. At all points in the
>>> digital system.
>>>
>>> Cole, AA7RD
>>>
>>> *From:*arm-allstar-bounces at hamvoip.org
>>> [mailto:arm-allstar-bounces at hamvoip.org] *On Behalf Of *LaRoy McCann
>>> *Sent:* Monday, April 20, 2015 11:47 AM
>>> *To:* BeagleBone Black ARM Allstar
>>> *Subject:* Re: [arm-allstar] excessive audio delay problem
>>>
>>>
>>> Yeah, you learn to pause before un-keying.
>>> It is worse sometimes than others.
>>>
>>> I have tried real hard to make it do that on the bbb and it has not
>>> done it.
>>> I was wrong on the radio on the bbb. At one time (pre lightening
>>> strike)I had a Master II with a cat 1000. Right now it is not my 80's
>>> hamtronics exciter with the latest synthesized receiver on the bbb.
>>>
>>> I wonder if different radios introduce different delays. I hope to
>>> get a chance this week to replace the bbb with a Pi2 and we'll see
>>> what difference that makes.
>>>
>>> Thanks for the info.
>>>
>>> LaRoy McCann, K5TW
>>>
>>>
>>> On 4/20/2015 1:19 PM, Doug Crompton wrote:
>>>
>>> LaRoy,
>>>
>>> The problem you are seeing has been a problem in Allstar for
>>> years. It tends to be worse on a slower processor like the BBB or
>>> RPi2. We are currently working on a fix which will benefit all
>>> Allstar users. However for right now there is no cure. Setting
>>> rxaudiodelay to eliminate squelch tail in simpleusb.conf would
>>> make it worse as it would add to the delay. It is variable meaning
>>> at times it is almost lockstep and at other times several hundred
>>> miliseconds or more delay. Also depending on the receiving radios
>>> recovery time it may be better or worse. Using PL usually helps it
>>> as it slows down RX recovery time. Hang in there we will have a
>>> fix in the future. This is not a problem on a simplex node.
>>>
>>> For those that have not experience this what you hear is a last
>>> syllable of your transmission when you release the mike. It can be
>>> annoying but is not a show stopper.
>>>
>>> *73 Doug
>>> WA3DSP
>>> http://www.crompton.com/hamradio*
>>>
>>> > Date: Mon, 20 Apr 2015 12:38:54 -0500
>>> > From: lmccann at dtisp.com <mailto:lmccann at dtisp.com>
>>> > To: arm-allstar at hamvoip.org <mailto:arm-allstar at hamvoip.org>
>>> > Subject: [arm-allstar] excessive audio delay problem
>>> >
>>> > I have a Pi2 running on a GE Master Executive II repeater.
>>> >
>>> > The problem I am seeing is that if I un-key my mobile too
>>> quickly, I
>>> > will hear the last several words that I just spoke being
>>> transmitted
>>> > back from the repeater. Is this board just this slow or is there
>>> some
>>> > audio delay setting somewhere I am missing.
>>> >
>>> > I have a bbb running on a GE Master II and it works fine. I'm
>>> going to
>>> > try a Pi2 on the Master II to see if it is in the controller but
>>> wanted
>>> > to ask here to see if anyone has experienced the same issue.
>>> >
>>> > LaRoy McCann, K5TW
>>> >
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>>> >
>>> > Visit the BBB web page -
>>> http://www.crompton.com/hamradio/BeagleBoneBlackAllstar/
>>> >
>>>
>>>
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>>
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