Transient Click at start of aplay audio?

mrperrier · Post by **mrperrier** » Sat Sep 30, 2017 6:03 pm

Hi there,

Just got this Octo, pretty cool.

Would like to see if anyone has experienced a click at the beginning of aplay. It seems that if you play a short sound and another quickly afterwards there is not a click at the beginning but if you wait a time the click returns.

Any advice in dealing with this is appreciated.

Thanks.

flatmax · Post by **flatmax** » Sun Oct 01, 2017 2:06 pm

Hi there,
There should be some alsa mixer settings to change these clicks ... not near an octo right at this point, will look for them soon.

Matt

mrperrier · Post by **mrperrier** » Mon Oct 02, 2017 4:26 pm

Hi Matt,

Thanks for the quick reply.

I just did a test, changing alsamixer settings on the DAC (immediate, zero cross, soft ramp, soft ramp w zero cross) and the behavior in aplay stays the same. Still a click at the beginning on playing a short sample with aplay, if the playback is repeated shortly after there is no click, waiting a few more seconds before playing the short sample again the click is back.

Any ideas?

Thanks!

flatmax · Post by **flatmax** » Mon Oct 02, 2017 8:54 pm

OK - I have a feeling this has something to do with ALSA DAPM. Just to be clear, this is an output only issue - right ? Nothing to do with recording ?

Hmm ... I wonder if there is a way to turn off ALSA DAPM ... that would be the solution.

If you were to comment out DAPM widgets and routes here and recompile the audio module :
https://github.com/raspberrypi/linux/bl ... ard.c#L247

That would most likely remove DAPM and fix your problem, because the power would remain on all the time. NExt time I am fiddling with the driver, I will look into this for you.

Matt

mrperrier · Post by **mrperrier** » Tue Oct 03, 2017 2:15 am

I am not sure if this problem exists in recording as my application is playback-only.

I will try recompiling this, commenting out the DAPM.

Interestingly omxplayer does not produce this clicking however I am using aplay because it's faster to playback.

I will keep you updated. I realize this problem is not unique to the octo, thanks for your help.

mrperrier · Post by **mrperrier** » Tue Oct 03, 2017 4:37 pm

Having some trouble recompiling and installing this module, can you give me a rundown of how you'd do it?

flatmax · Post by **flatmax** » Wed Oct 04, 2017 7:22 am

ok sure.

I decided to create a new post for a kernel hacking guide for the Pi :
http://forum.audioinjector.net/viewtopi ... 5226#p5226

Matt

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