Advice needed: repairing auto-gain volume jumps

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MartinC
Posts: 30
Joined: Thu Oct 15, 2009 3:01 pm

Advice needed: repairing auto-gain volume jumps

Post by MartinC »

Hi,

I'm aware that this is not a specific AP question, but this is a very nice community so I thought it's worth to just ask... :wink:

I need to (roughly) "repair" a couple of long tracks with "jumping" volume/gain levels - a bit like old analogue recordings with auto-gain control instantly turning volume down at certain peaks and then moving it up again very very slowly.

I only need a "rough" repair to start with, so I wondered if it can be done automatically in reasonable quality. An instant idea is the "Dynamics" filter, like the AUDynamicsProcessor from Apple or the VST mdaDynamics one.

However I must confess that I have zero experience with this, the filter is not really *meant* to do this in the first place and it has some 7-10 separate sliders...

So without both first-hand knowledge and/or a manual for this specific (mis-)use it is hard to do random trial-and-error.

I managed to get "bad but somehow promising" results by trying some extreme "min/max" settings of some rulers, but especially "ratio" gives very different results in combination with other settings, so that I'm rather lost with any further improvements.

Is there anybody here who could give me a very short advice, where to start - like "this and this" should be set to minimum, "that and that" should be set to maximum and the other ones need to be fine-tuned afterwards...?

Or: Is there any other (type of) filter that would be better suited for this kind of job?

Thanks a lot in advance for any help! :D

Gerard Bik
Posts: 353
Joined: Fri Nov 10, 2006 9:04 pm

Advice needed: repairing auto-gain volume jumps

Post by Gerard Bik »

I have no experience with this problem but what you want is the opposite of Compression: Expansion.
Try to recreate the settings of the compressor in reverse.

"Soundhack +compand" might enable you to do it. There are probably better plug ins available.
Tip: sometimes correcting the bad parts manually is the fastest solution.

Gerard
Hi,

I'm aware that this is not a specific AP question, but this is a very nice community so I thought it's worth to just ask... [Wink]

I need to (roughly) "repair" a couple of long tracks with "jumping" volume/gain levels - a bit like old analogue recordings with auto-gain control instantly turning volume down at certain peaks and then moving it up again very very slowly.

I only need a "rough" repair to start with, so I wondered if it can be done automatically in reasonable quality. An instant idea is the "Dynamics" filter, like the AUDynamicsProcessor from Apple or the VST mdaDynamics one.

However I must confess that I have zero experience with this, the filter is not really *meant* to do this in the first place and it has some 7-10 separate sliders...

So without both first-hand knowledge and/or a manual for this specific (mis-)use it is hard to do random trial-and-error.

I managed to get "bad but somehow promising" results by trying some extreme "min/max" settings of some rulers, but especially "ratio" gives very different results in combination with other settings, so that I'm rather lost with any further improvements.

Is there anybody here who could give me a very short advice, where to start - like "this and this" should be set to minimum, "that and that" should be set to maximum and the other ones need to be fine-tuned afterwards...?

Or: Is there any other (type of) filter that would be better suited for this kind of job?

Thanks a lot in advance for any help! :D




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MartinC
Posts: 30
Joined: Thu Oct 15, 2009 3:01 pm

Re: Advice needed: repairing auto-gain volume jumps

Post by MartinC »

GerardBik wrote:I have no experience with this problem but what you want is the opposite of Compression: Expansion.
Try to recreate the settings of the compressor in reverse
It's a bit point of view actually... if you consider the loud parts to be "correct" then it is expansion, but if you consider the low parts to be "correct" then it is classic compression... so it should make no difference in the settings except for a final (global) raise of gain.
GerardBik wrote:"Soundhack +compand" might enable you to do it. There are probably better plug ins available.
Tip: sometimes correcting the bad parts manually is the fastest solution.
Thanks, I will have a look if the controls allow for better trial-and-error. My main request was for a little help with certain sliders... attack, release and threshold are abvious, but "ratio" gives very strange results and I'm not really sure what the value means - especially because it is something different with every filter - the Apple one has "1-50", but the VST one has "0.5" to "19" (on the left) then "LIMIT" (in the middle) then "-1.04" to "-17" (on the right end of the scale)... what the *heck* does this mean??? :shock:

MrEes
Posts: 64
Joined: Fri Nov 10, 2006 7:52 pm
Location: Finger Lakes, NY, USA
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Advice needed: repairing auto-gain volume jumps

Post by MrEes »

MartinC expressed with much marked refinement of phraseology:
GerardBik wrote:
"Soundhack +compand" might enable you to do it.
+1
Thanks, I will have a look if the controls allow for better
trial-and-error. My main request was for a little help with certain
sliders... attack, release and threshold are abvious, but "ratio" gives
very strange results and I'm not really sure what the value means -
especially because it is something different with every filter - the Apple
one has "1-50", but the VST one has "0.5" to "19" (on the left) then
"LIMIT" (in the middle) then "-1.04" to "-17" (on the right end of the
scale)... what the *heck* does this mean??? [Shocked]
http://en.wikipedia.org/wiki/Dynamic_range_compression

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MartinC
Posts: 30
Joined: Thu Oct 15, 2009 3:01 pm

Re: Advice needed: repairing auto-gain volume jumps

Post by MartinC »

Thanks, I knew that (and similar overviews).

The "Soundhack +compand" filter certainly has the advantage to label the "ratio" dial correctly.

I did a search on the other filters before but couldn't find anything useful... I have no idea what the Apple "1-50" means, although I got the best results with it so far - I found one setting that nearly does it. However, changing this value just a tiny little bit creates entirely different and random results. I can think of no "real ratio" that would work like this...

The mda one is entirely weird - I guess the positive/negative numbers indicate a dB value rather than a ratio. But the only information on the net that I could find suggests a range of "0-1" for the dial, with 0.20-0.30 being the range to use for ordinary purposes (It says 0.20 = 1:1 and 0.30 = 1:16... obvious, eh!? :lol:), and the rest being "experimental". Well... looks like it, and hardly documented as well. And they changed it recently for something even weirder.

I will try "Soundhack +compand" now, but initial tests are frustrating - it makes minor changes but leaves the massive gap in dynamics. The ratio-dial does little to nothing on my files.

I think the Apple filter is the most drastic one, but virtually uncontrollable...

MartinC
Posts: 30
Joined: Thu Oct 15, 2009 3:01 pm

Post by MartinC »

To whom it may concern... :wink:

If anyone ever has a similar problem, I finally got a weird workaround. It makes me wonder why nobody ever tried to provide a "standalone" plug-in to do exactly this, because it happens to work pretty good.

I'm using "Soundhack +compand" with obvious settings:
- a high ratio, something like 20:1
- threshold matching the lowest parts
- shortest possible attack
- longest possible release

This works perfectly for parts getting louder, but it leaves audible "low holes" when parts are getting lower, because the release takes time before the attack rises it up again. However, making the release time shorter results in "volume pumping" like in cheap tekkno-remixes.

Every attempt to cope with this resulted in worse results until I finally got the magic idea: "parts getting lower" are actually "parts getting louder" if you invert it !!! :shock:

So I'm doing this:
- make a copy of the track
- invert the second track
- run +compand over both tracks
- invert the second track again
- merge/blend both tracks

The result is *seriously* better than any single-track attempt, no matter which settings. 8)

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