[App_rpt-users] First experience with ACID app_rpt & usbradio audio popping problem.

Stephen Rodgers sales at qrvc.com
Sun Nov 15 21:23:01 EST 2009

Steve Gladden wrote:
> Hi David.. it's not a terribly loud popping it's right with the normal audio
> levels
> It really sounds like 'holes' in the processing small abrupt dropouts of the
> stream..
> Very random in timing maybe 5-15 hits per minute when I key the radio with
> PL..
> Seems to more frequently happen on/around the CWID but still is happening
> very randomly.
> CPU utilization is ~10% while radio keyed producing PL and CWID..
> Have radio continuously keyed (no actual radio) and CDID beacon going every
> minute.
> 5-15 'dropouts' per minute.
> I've tried to isolate it by throwing different tasks at the hardware/CPU to
> see if the audio dropouts
> Would increase or not during heavy CPU utilization or maxing out IO on
> network hard drives etc.
> Checked alsa mixer to make sure there were no open turned way up audio
> inputs or mic monitor turned on..
> Turned down all input levels and this had no effect on the dropouts either.
> One thing I have not tried (but will not matter) is to hook a usb HDD to the
> usb port and give the usb controller
> Itself some activity besides the usbradio port and see if this impacts the
> issue.
> This might tend to point me back to the usb controller itself having an
> issue..
> I should also try a PCI external USB card on the motherboard and give it
> it's own interrupt.
> :-)
> -----Original Message-----
> From: David McGough [mailto:kb4fxc at inttek.net] 
> Sent: Thursday, November 12, 2009 6:57 PM
> To: Steve Gladden
> Cc: app_rpt-users at qrvc.com
> Subject: Re: [App_rpt-users] First experience with ACID app_rpt & usbradio
> audio popping problem.
> Hi Steve,
> What exactly do you mean by "popping"?? Is it a loud POP! like a drum or 
> is it a momentary audio drop-out or choppiness??
> The reason I ask about choppiness is that I've experienced this issue. 
> But, I've never had loud POPS! ....
> 73, David kb4fxc
> On Wed, 11 Nov 2009, Steve Gladden wrote:
>> Short version:
>> *Installed ACID
>> *Have audio popping problem with USB transmit (output) audio.
>> *I'm not surprised didn't expect it to work perfectly first attempt.
>> *Only tried one combinarion of hardware/cpu/motherboard so far.. I need 
>> to try other motherboards/CPUs.
>> * Tried 3 different USB devices and ports.
>> * played with moving interrupts disabling motehrboard built-on hardware
> etc.
>> * CPU runs at about 10% while USB radio is active..
>> * Loading PC heavily by running gzip -9 seti at home Lots of disk access 
>> lots of network activity seem to have zero impact on the popping 
>> frequentness.
>> * I'd like to know if anyone else here has had this or similar problems 
>> with consistent audio from the USB device (CM-108) and what they may 
>> have done
>>   to make it work better.
>> Long Version:
>> I gave it a go and went the 'easy' route just to get started..
>> I ended up trying it out on that 1.1Ghz AMD Duron CPU rack mount server..
>> I must say I'm extremely excited & please with this software..
>> But it would be too good to be true if it all just worked first try.. 
>> and of course would take all the 'fun'
>> out of getting it to work..
>> Ok enough small talk (haha)
>> Here's what I have going on:
>> Everything works except I am getting intermittent audio popping in the 
>> audio output of the USB sound device.
>> VERY intermittent maybe about 3-4 'pops' every minute on average.. 10 at 
>> most sometimes.. and other times several minutes go by without a 'pop'.
>> It seems to mostly occur during the CW ID beacon which I have going 
>> every minute..
>> The pops that are heard only happen when the 'transmitter' is active 
>> sending PL or CW ID or PLAYBACK...
>> My test arrangement has "radio key" running to produce continuous PL and 
>> occasional audio popping.
>> There is no radio actually hooked up yet.
>> OK will talk about the hardware a bit.. and probably worse case scenario 
>> here due to an 'all in one' motherboard..
>> It's a MSI 6378 'budget' Athlon board.. everything built on.
>> Has USB 1.1  *NOT 2*
>> I don't know/think this matters for a sound device.
>> Here's all of the things I have tried all of which have absolutely no 
>> effect on the intermittent popping...
>> 1. Disabling everything not needed on motherboard including ethernet for 
>> test..
>>     ethernet + usb share an interrup line and there is no ability to 
>> re-route this in the bios
>>     so I turned off the ethernet on the motherboard for testing.
>> 2. Carefully monitor CPU during audio pops running 'top' around 20 
>> updates per second (this alone takes more CPU load than asterisk 
>> /app_rpt + usb radio.
>> 3. On this motherboard the USB controller and ethernet share a PCI 
>> interuupt line and you cannot change it.
>>     I've tried disabling the built on ethernet and still get the popping..
>>     I've also flood and large pinged the machine which genreates huge 
>> numbers of interrups from the ethernet chip and this has no effect on 
>> the popping..
>> 4. Tried other USB fobs with same chipset.
>>     Created various types of heavy system activity to see if it has any 
>> impact on the popping heavy disk use hevy network use and heavy vga use 
>> (text mode)
>>     moving interrupts  (changing them) on the motherboard.. getting usb 
>> controller onto a different interuupt (ethernet ends up on same).
>> 5. Measured and scoped 5V output on USB to be sure 'popping' sound is 
>> not coming from 5V power supply.
>> 6. Am really looking to hear what some others experience has been with 
>> this..
>>     what works and what does not?
>>     The popping very much sounds like an interrupt issue or some kind of 
>> issue where the task of sending and audio stream is completely dropped 
>> for something else
>> and then resumed leaving lots of holes heard as pops in the output stream.
This is reported occasionally, but I've never experienced it.

Given what you've tried already, I'd try a different motherboard.

Also, remove any usb hobs if you are using one.


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