Sound crackle when looping audio file

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Tomasm21
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Sound crackle when looping audio file

Post by Tomasm21 » Wed Dec 02, 2015 1:44 am

Hi. I'm new here. But I will explain my problem.
I record sound that passes through sound card. Or I record using another program but use WaveLab to process sound.
I'm using Version 7.2.1 (build 600) - 64 bit
I have recorded sound from Stereo Mix. And I'm using this wavelab to add some more deciBells to overall sound peak: Process >> Change Level... +3 dB. This is increasing sound amplitude. But it never reach 0. Sound is stronger and it is more pleasure to listen. Then I save it as ogg file. But when I play it on third party player (winamp) sound is crackling at starting. Actually this is happening when track is being looped. It cracks a bit and continues playing again 49 seconds. I need it to be clean without any distortion. I have recorded 49 seconds of white noise from Star Trek TNG HD Ambient Engine Noise. Same sound continues 12 hours but for my project I need onle a little piece of it. It can be even 10 s.
However I was thinking what could be a reason. And I came up to conclusion that it is because of level mismatch > the difference between ending state and starting state. To better understand what I mean look at these pictures:

Here is the track in general view (Click to enlarge):
Image

Here is the ending state (Click to enlarge):
Image

And this is the starting state (Click to enlarge):
Image

As we can see when the track is looped then because of the ending and starting level mismatch crackle can be heard. Am I right? Or maybe crackle reason is different?

This is pretty steady sound. You can download and open it in your wavelabs from HERE (Click to download) .
If I am right then can you explain how to avert such crackle during restart? Does WaveLab has any miracle functions that equalize ending and starting sound levels? Or can it detect repetetive chunks and to select it? Or do I have to record it correctly? Or maybe it is possible with pencil to draw curve that it would match? And would it guarantee absolute smooth sound?
Listener must not hear any crackle or distortion. The sound must be so good that he would not be able to know where is start and where is the end.

Sincerely, Tomasm21

bob99
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Re: Sound crackle when looping audio file

Post by bob99 » Thu Dec 03, 2015 9:40 am

Search for Loop Tweaker in the Help menu.

I would only expect a tick or click at the crossover point with your current setup, not a lengthy crackle. Maybe you should pull in your edges a bit before using the Loop Tweaker, in case there's existing crackle at the beginning or end of your file.

Tomasm21
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Re: Sound crackle when looping audio file

Post by Tomasm21 » Thu Dec 03, 2015 12:47 pm

I haven't found such think as Loop Tweaker. But I have inserted 3 secs of silence after the end of sound and 3 seconds before the start. This your mentioned "tick or Click" can be heared both at the end and at the start as soon as playing line crosses the point between silence and sound. I really need to vanish this "Click" because it would let a listener to determine starting and finishing point. And therefore to think that technology I use is useless. But I'm sure this "click" sound is inevitable because of technological/physical laws. I need to keep clean sound without that click.

PG
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Re: Sound crackle when looping audio file

Post by PG » Thu Dec 03, 2015 1:15 pm

Don't use a compressed file like ogg if you want perfect looping.
Philippe

bob99
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Re: Sound crackle when looping audio file

Post by bob99 » Thu Dec 03, 2015 9:48 pm

Sorry, maybe the Loop Tweaker isn't in Wavelab 7.

But I'm not sure your project would ever be seamless if you're depending on a user's player (like Winamp, or WMP, or iTunes, or a DVD player main menu) to do the looping. Isn't that what you're doing? Supplying a short audio file that's looped by the user's player? My experience is they'd all do it differently.

And what PG said, problems looping compressed files, although I found Wavelab Ogg more seamless than MP3 or AAC on most players when I tested live files for continuity in players.

But like you said you could use the pencil tool with a steady hand and get the loop pretty perfect on WAV in Wavelab, but after that, depending on a user's player to do the loop? That could be different in every player, and would probably be audible in every one, whether with a click or a gap or a player crossfade creating a dip.

Maybe somebody else has a perfect solution for this, but it sounds problematic to me.
You could line up multiple copies in Montage and adjust clip edges for the closest match, then re-render, that's one possibility.

The Youtube appears to be an actual 12 hour audio stream he created from a loop, not a short audio piece looped by the Youtube player. If it was being looped by the Youtube player the crossover points would probably be audible there too.

Maybe I'm misunderstanding and you're not depending on the user's player to play the file looped (?), but you didn't say you're creating an actual hours long stream like the Youtube file.

Tomasm21
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Re: Sound crackle when looping audio file

Post by Tomasm21 » Fri Dec 04, 2015 12:22 am

Bob, I'm creating short ambient sound. Such sounds in the game like DOOM are point sounds and they are looped as long as player is in sound area. New source port of Doom the ZDoom provides many popular formats from wav to ogg. As I was listening to loop quality there I can confirm that loop is perfect - better than most players. I'm not making twelve hour tracks. The reason why I compress to ogg is because wav takes too much space. The mod with many various sounds would be big. I'm using WaveLab LE7. In toolbars I don't see pencil thing yet. I'll try to search in various options and settings. I will try to line up multiple copies in montage. I'm doing it. I don't know whether I will succeed. I have an idea >> the second copy of the same clip to set vice versa (contrarily). I mean so the end of the track would become the beginning and the beginning the end. The lines would match but track length would be doubled. But would it sound different? Question: How to turn the track backwards?

I have realised what I have just said and I'm ROFL :D. Of course the second part would sound differently but lines would definitely match.

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