removing crackles

[Prasa_U.]

I have this file, listening to it again I realized there was about 2 seconds worth of small crackling audible at a certain point. Very few people would notice it, especially since the entire track is six minutes. But, my question is, is it possible to be able to remove that small instance of crackling without causing harm to the track itself, or without redoing it. (Keeping in mind I am not a master when it comes to production and mastering)

[Kanjika]

If it's done in a sequencer, why not just re render / record your track? If it doesn't go away there's a problem with a sample or plugin. If you can't do that, I'm not aware of how to completley remove crackling, but if it's at a high freqency, you could maybe EQ some of it out without causing too much alteration to the other sounds.

[Villainelle]

What's causing the noise? If it's clipping, you really should fix it in the project file and re-render. Open the file in any audio editor; is there a flat line in the waveform at the point where you hear the crackling?

If not, then yeah, you can attenuate the noise by EQing. Go to the part of the track where you hear the crackle. Set up an EQ filter with a very narrow band, and either raise or lower it as far as you can go, then sweep it through the frequency spectrum until you hear it either emphasizing or deemphasizing your crackle (depending on whether you're cutting or boosting)--where the crackling sound reacts, you've found the frequencies you need to cut. Automate the EQ to just apply a cut to those frequencies during the crackling, and re-render. You may want to chain several EQ plugins together if the sound needs a lot of cutting to attenuate it to where it's not so noticeable. Try to keep your EQ band as narrow as possible to avoid affecting the rest of the sounds playing at that moment.

There are some plugins that attempt to do this automagically. Check kvraudio.com.

edit: BTW, are you sure the file isn't corrupt somehow? You didn't mention if it was a WAV, MP3, or what. If it's an MP3, try just re-encoding it from your source file first. If it's a WAV and it's *not* clipping, and you don't remember hearing that crackle while you were mixing, maybe the file is corrupt. It's best to re-render if you can rather than trying to find a band-aid for it.

[po!]

I have this file, listening to it again I realized there was about 2 seconds worth of small crackling audible at a certain point. Very few people would notice it, especially since the entire track is six minutes. But, my question is, is it possible to be able to remove that small instance of crackling without causing harm to the track itself, or without redoing it. (Keeping in mind I am not a master when it comes to production and mastering)

if you're talking about really short crackles, then it can be easily removed. you should see an abnormal spike in the waveform which you can manually smooth out by changing the actual sample values

if you're not sure what i'm talkin about, you could post the 2 second audio sample i can show you how its done

btw i would NOT recommend using EQ. you don't wanna ruin the balance of your mix just to fix a little crackle

[Theowne]

I don't think it's clipping, there are much louder parts later which don't crackle at all. What I don't understand is, even when I re-render it still crackles at this part.

Here is the 2 sec im referring to

[chrono26]

i dont hear any crackle. what kind of speakers do you use?

[po!]

yea i don't hear any crackles, aside from the beginning and end.. is that what you're talkin about?

that's usually caused by abruptly putting in a sample/waveform without properly fading it in

but if that wasn't the problem then you can do the fade in/outs after mixdown

[zircon]

Yeah, what po! said.. waveforms should start and end at a zero crossing to sound properly. However I do hear a little bit of distortion towards the left side on that timpani roll. Maybe he meant that?

[Prasa_U.]

No, the crackling should be during the timpani roll. Do you really not hear anything? I can hear them both on my sony headphones and on my logitech speakers, though it's less audible on the speakers. But if no one else hears any problem....

[po!]

ok i've removed the crackles

http://wushuplaya.googlepages.com/clipp2.mp3

here's how i did it:

1) this is the crackle at the end of the clip. you can see a spike there, which causes crackle

2) selecting the spike, i put a fade out envelope over it

3) spike is smoothed out, no more crackle

this was a special case tho.. usually crackles don't occur at the beginnings or ends, so in that case you can't use fade in/out. you have to manually edit the waveform to smooth out the spike

EDIT: so the crackle is during the timpani roll.. hmm.. lemme go find it

EDIT2: ok this is reaally hard to find.. sorry i don't think i have time right now to go looking for it

[zircon]

No, the crackling should be during the timpani roll. Do you really not hear anything? I can hear them both on my sony headphones and on my logitech speakers, though it's less audible on the speakers. But if no one else hears any problem....

Yes, I did mention that I heard some distortion in the timpani roll. It's not clipping in the file itself, it sounds like the recording distorted a bit somehow. But without knowing more info it's a little hard to diagnose. Do you only have the MP3 file? Is this a song you wrote, and if so did you use samples, or what? If the timpanis got distorted (clipped) in the recording process you can't really do much after the fact.

[Prasa_U.]

ok i've removed the crackles

Thanks for the write-up, but yeah, I was referring to the crackles during the timpani roll, the clip is part of a larger song and the beginning and ending noises don't appear when it's in the song. I just did a quick cut of it to show the clip. Thanks for the effort though.

Yes, I did mention that I heard some distortion in the timpani roll. It's not clipping in the file itself, it sounds like the recording distorted a bit somehow.

The thing is, if I reduce the volume and render it , the crackling isn't there, but I have a louder timpani roll later in the piece and yet there is never any clipping there at all. Is there any reason why that could happen? Yes, it's samples, not a recording.

[zircon]

Have you tried rendering as WAV to see if the crackles are still there then? Also, try muting the other parts and exporting JUST the timpani track. Isolate whether its the samples causing it or a general mixing problem w/ the project.

[po!]

ok i've made a clip so you can hear the crackles better

http://wushuplaya.googlepages.com/clipp3.mp3

i have no idea where the crackles are coming from. i don't see any spikes in the waveform

i'd guess its a problem in your program when rendering/exporting. try exporting the same clip a few times and see if the crackles are in the same places. maybe try some slight variations (like slightly move a timpani hit out of time) and see if the crackles are different

[B33J]

The crackle is *right after* (or right on) the 1 second mark. I can certainly hear it too.

[analoq]

my hypothesis:

the timpani roll clips briefly due to numerous overlapping samples.

theoretical solutions:

1. reduce the length of the MIDI notes on the timpani roll

2. shorten the volume envelope for the timpani sample

3. reduce the maximum polyphony of the sampler with the timpani loaded

just a guess, but might be worth a shot.