I run KDE 4.7 and I noticed that when I play music with vlc, mplayer, or mpd and Desktop Effects are enabled, then my sound crackles when I switch windows or check a checkbox.
My graphics card is a 470GTX and I use the nvidia 280.13 driver.

Did anyone else experience something similar or have an idea on how I should go about getting rid of the distortion?

Thank you.

can't replicate using a 9500gt and 280.11

did it always do this or did it occur after a particular update?

what kind of music files are you playing?

try 1) disabling blur and 2) as a different user

also - does this happen when using Amarok?

which audio output module/driver are you using? try switching to pulse or alsa

Thank you for your reply.

I believe I heard the crackle all the way from KDE 4.5, but I just didn't notice the context in which it consistently happened. It actually only happens when any sound goes through my headest and not my speakers.

My headset is USB, Razer Megalodon. Replugging it in does not help, neither disabling Blur. The problem persists with both Pulse and Alsa.

Thanks for the ideas which led me to find that it is only a problem with my usb headset.

rename (or create new thread) with "usb headphones" included in subject line

6 months later I'm still having the same issue. Some new information I found is that if I completely disable effects in KDE, there is no crackle when I play music. If I toggle desktop effects on, any sound that is playing crackles when I trigger a desktop effect.

Very, very interesting. It seems that either KWin/X/Graphics drivers are causing this... If you try with an alternative compositing window manager (or alternatively, another application which uses OpenGL, preferably one which is as intensive as possible) to help eliminate the Graphics drivers/X?

My issue has been mitigated by Madman on irc. He suggested I uncheck the "Enable animations" box in Settings -> Workspace Appearance -> Window Decorations -> Configure Decoration. After unchecking the box, there is much less crackle when I play music and trigger a desktop effect.
Further tinkering and experimenting reveals that animations can be used, but it is specifically the "Window active state change transitions" checkbox that needs to be unchecked for my issue to be mitigated.

There is still a very slight blip every time I activate a desktop effect, so I will continue to pursue this issue. I'll try switching to a different compositing manager and post back the results.

Please report this issue on KDE Bugzilla - as it should not be causing any measurable change in the performance or operation of your system.

https://bugs.kde.org/show_bug.cgi?id=293884

Additional info: It only happens on my Razer Megalodon headset, not my onboard sound card. Also, even with Desktop Effects turned off, resizing a window causes a crackle.

I will be trying a different compositing manager soon and will post results.

This is now resolved after I stopped overclocking my CPU. I brought it back from 3.0GHz to 2.4GHz.