[op25-dev] Audio Dies Pt2 and JSON meta tags????

Graham Norbury gnorbury at bondcar.com
Mon Feb 25 11:00:21 UTC 2019

Localizing the problem is going to take some detective work.
1. Determine whether op25 is receiving, decoding and outputting audio. 
Depending how you run your log level, I'd suggest first looking for
"voice update" messages which are produced at level "-v 1" (or greater)
every time op25 tunes a voice channel.  Once that is confirmed, I'd look
for occasional "PCM underrun" messages that are occasionally emitted by
sockaudio when there are inevitable lost frames or processing delays. 
You should be able to get a sense of the approximate frequency looking
back at the log when audio is known to be good.  Sudden absence of these
sporadic underruns would suggest either op25 stopped sending pcm or the
alsa subsystem had an issue.

2. Compare the behavior when outputting to 'aloop' vs 'default'
(speaker) device.  In the past when I've seen the sudden absence of
audio, it has only affected output to aloop.

3. Consider temporarily testing with the internal audio player disabled
(remove the -U and make sure you have -V -w) then run an instance of nc
| aplay  Generally 'nc' is quite chatty when it's running so you should
be able to see if raw udp samples stop arriving at some point.

Let me know what happens.

On 2/24/19 7:34 PM, op25 at zellners.com wrote:
> Quoting Graham Norbury <gnorbury at bondcar.com>:
>> This is not a unique problem especially with RPi3 and aloop/darkice.  My
>> recommended solution is to switch over to liquidsoap which avoids
>> alsa and
>> aloop altogether.  Instructions can be found in the
>> README-rpi3-liquidsoap
>> file in the top level op25 directory.
> First, MY PI3 op25 is humming along with darkice and audio quite
> fine... its only issue is when metatag updates fail causing a crash..
> thats fixed in a later version, but I can't update that part right
> now.. listening to it right now after days and days of running....
> Second, LAPTOP setup is the issue.....
> Thrid, I planned to do a different test today, but a hardware snafu
> nixed that, till later..
> Fourth... I have had the laptop taking audio from VLC output to loop0
> and its been playing for hours...this is continous audio... I just
> took my mp3 NAS and dumped it into VLC! :)
> Fifth, I do NOT LIKE liquidsoap. I have my reasons, mainly I KNOW
> DARKICE, and use it extensively for years.
> So with audio flowing non stop locally on the laptop
> And audio flowing from a VLC Playlist out aloop0
> op25 seems to be the issue...'
> Now the the only difference in this is a CHANGE IN SYSTEMS from a
> local about 3 air miles to a new system coming online, tower is 12 air
> miles away... I was using op25 to monitor another part of this system
> that was about 20 air miless away....
> The signal is about ~30-31db for each channel, CC or traffic, and
> audio is clean and crisp.. when I let it only play on local .... I was
> using the same laptop for the local system and feeding it out
> darkice/aloop....I just was not monitoring it close to see if it was
> dying and was futzing with what it was monitoring etc.. so I can't
> 100% verify that it was pumping out audio 24/7 on that system...
> So one thing could be signal strength, but that should only matter in
> the recovery of the CC and audio. Constellation looks good, eye
> pattern looks good... steady stream of CC data, even dealing with the
> rotations.. Harris system.... they have taken their rolling CC from
> EDACS and added it to their P25 CAI, more so than just normal.. which
> when monitoring the part of this system system 20 miles away, I saw CC
> decode issues, missing audio... to be expected.. the system is setup
> so as not to cover me from that site(s)... its a dual zone setup
> similar to their existing system... not really sure why keep this in
> P25.. but considering the vendor is the same, it doesn't surprise me....
> I probably will take and revert this back to the local system
> overnight to see if audio comes out of this thing 24/7 and then
> proceed from there...
> I will most likely try my Pi3 setup with this system when I can set it
> up... and then see if it works... with dakrice/aloop...
> What I am after is getting way to pinpoint where the issue is.. op25,
> aloop, what ever... Some may have an affinity for liquidsoap, just as
> I have affinity for darkice.. I use ALSA plugins to act as sort of
> split to take a single stereo input and send out 2 feeds with out
> issues..24/7/365 for over 10 years. And like I Said I am listening to
> the PI3B with darkice/aloop feed out out audio right now.. just a
> different system.... which I am hoping is not the culprit... Motorola
> v. Harris?, signal... (Note: I use commercial antennas and LMR cable,
> the antenna for these systems is 25 feet in the air above local scrub
> and I actually will put a yagi onto this in the final setup... its on
> the omni right now
> Ultimately this has to run on Pi3b+'s as my setup for op25... and I
> need to setup probably about 3-4 for this system once its full blown
> use.. so if I get things to work on the Pi3b+ as a test then I will
> just go with that... and chalk the laptop upto an anamoly... I would
> mostly use it for local audio any way..
> The laptop was pushed into this due to the users in one group
> switching sooner than I was planning on them....

More information about the op25-dev mailing list