Re: Crackling Noise In Playback

Jay Foster <jay@xxxxxxxxxxx> · Thu, 4 May 2017 09:23:05 -0700



    On 5/4/2017 8:50 AM, chris hermansen
      wrote:

    
      Jay and list,

        
          On Thu, May 4, 2017 at 8:24 AM, Jay
            Foster <jay@xxxxxxxxxxx>
            wrote:

            I have
              encountered a strange problem.  About 6 months ago, I
              added a USB

              sound adapter and alsa to an ARM based linux system.  I
              used aplay to

              play wav files successfully.

              Now, the playback has a crackling noise in it.  I can not
              find anything

              that has changed.  A few units still play with no noise,
              but I cannot

              determine any difference between them and the ones with
              the noise.

              
              One odd thing is if I run an application to make the CPU
              busy while

              playing the audio wav file, the noise seems to go away. 
              Any ideas on

              where to look for the root cause?

              
              Jay

              
            I have had a similar experience using an AudioQuest
              DragonFly and a CuBox i4.  In my case, errors were
              reported in syslog.  Do you show any errors there?

              
            Do you have any other USB sound cards to try out? 

            
          -- 

          
            Chris Hermansen · clhermansen "at" gmail
              "dot" com

              
              C'est ma façon de parler.
          
        
    I have tried 3 different USB audio dongles (all C-Media chip
    based).  No difference.

    No messages in /var/log/messages.

    I had to put the following in my /etc/asound.conf file to get clean
    playback when I originally got this working (the CPU is too under
    powered to do the default rate conversion).

    
        defaults.pcm.rate_converter "linear"

    
    The noise is also present using 'speakertest -c 2 -t wav'.  What
    bugs me is that this used to work fine, and still does if I make the
    CPU busy, which seems counter intuitive.

    Jay

  
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