What causes pops and crackles?

[lordmaiku]

I'm wondering what causes pops and crackles when playing back audio files... these sound artifacts occur intermittently when playing songs, and seem to occur anywhere in the track (when starting, somewhere in the middle, or at the end). Sometimes it happens several times in the same track, but never in the same places on the next play through.

I've tried increasing the buffer, changing the update period, forcing software mixing, etc, but nothing seems to make this random noise go away. Also: running other CPU intensive tasks at the same time as my app doesn't seem to affect this problem (i.e., it's not any worse)

If this is a driver/card issue (RealTek I think... whatever comes in the Intel iMac, running Vista with Bootcamp) why don't other, much more complicated applications (*cough* iTunes *cough*) have noise issues during playback?

Thanks for any input

[JM-DG]

Are you using DSP Plugins when playing back your music???
This can be one of the problem source...

[radio42]

What programming language are you using?

[Ian @ un4seen]

To narrow-down the cause/location of the noise, you could try writing the stream to disk (while it's playing), eg. using BASS_Encode_Start on it; if the noise is present in the written file, then it's in the stream (or DSP) itself. If possible, you could also try to reproduce it with another soundcard and/or on another system.

[lordmaiku]

No DSP plugins. No custom streams or mixing (I am using BASSMix, but I noticed the same problems without using that).

Using C/C++. I've been careful to make sure my sync procs execute as fast as possible, and they are not calling any of the functions that 'steal' data (BASS_ChannelGetData et. al.)

I'll try writing the stream to disk and analyze that... and I can also try another PC/soundcard (Creative X-Fi card)... will get back to you on the results.

[lordmaiku]

After dumping the output to a .wav with BASSenc, I don't hear the same artifacts... at least, not in the same places. I don't notice the same artifacts on my other machine, although I didn't spend a lot of time there so I can't be 100% sure. Any ideas would be appreciated.

[Ian @ un4seen]

After dumping the output to a .wav with BASSenc, I don't hear the same artifacts... at least, not in the same places.

Does that mean that there are still artifacts present though, and are you sure they're not just in the playback of the recording, ie. do you hear them if you play the recorded file on your other (unaffected) system?

If the recording is fine, then that means the problem is in the output (rather than the stream), which I guess should mean that other apps are also affected. Can you reproduce the problem with the pre-compiled examples in the C\BIN directory?

[lordmaiku]

Yes, the other BASS samples do have the same problem, although possibly (?) to a lesser extent than my application. I spent all last night using iTunes and it also has the problem, but somehow much less noticeably. WMP is also minimally affected. The output files do not reproduce the artifacts on other machines.

SO, I figured for sure that this was a sound card/driver issue. I tried updating the RealTek drivers: no effect. And just now, I set up an external USB sound card (Creative X-Fi) and the problems seems to occur just as frequently as before (I did disable the built-in audio device). Now I'm _really_ confused...

[Ian @ un4seen]

Perhaps the noise is introduced after the sound has left the soundcard, eg. a dodgy cable/connection?

[JM-DG]

As funny as it may seems a lot of noise in the sounds comes from your computer's fan and computer's power supply. To put it simply the noise is transported trough the electronic. So if you have low quality computer's pieces the unwanted sound will be even louder.
When you want to make music use a good computer which is made only for this purpose.
As Ian says it may be also a bad cable...

[faggus]

so, i'm getting clicks, crackles in the mp3's that i'm playing, nearly all the 10 mp3 samples i've pulled.  now all are full length song mp3's, different artists, different songs, different sampling rates, different bitrates.  winamp, windows media player, itunes, all play fine, no clicks, or crackles.  no, i'm not running ghetto pentium 2 300mhz processors, no, my 2 gigs of ram is sufficient.  windows xp is tried and true, so it's not experimentalware. so the rig i'm using isn't causing a time delay for processing but maybe Bass.dll.  is anyone else getting this problem?  if so, how are you guys fixing it?  i'm using bass.net.  thanks.