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Dynamic Range Compression -- Settings

I'm looking for suggestions on settings for dynamic range compression -- values for threshold, ratio, attack, release, peak/RMS.

I have a collection of songs I play in my car, mostly pop/rock from the 1960s thru 1980s. Traffic and car noise tends to overwhelm the softer parts of the songs, so I'd like to use an audio editor, such as Audacity, to compress the dynamic range. The problem is that I don't know what settings to choose.

(I understand that dynamic compression is more of an art than a science, that, for best results, different songs may require different settings, but I don't want to spend time experimenting -- I just want settings that will give reasonable, 'average' results.)

Thanks in advance.

Dynamic Range Compression -- Settings

Reply #1
Quote
but I don't want to spend time experimenting -- I just want settings that will give reasonable, 'average' results.)
  Most audio editing requires some listening and some trial-and-error!    Once you find settings that work for you and your program material, you might be satisfied using the same settings for all of your files.

I don't use Audacity regularly, but I can give you some settings from GoldWave.

GoldWave's compressor doesn't have a gain control (maybe your "peak/RMS setting"), so with GoldWave, it's a 3-step process like this:

1.  Normalize (set the peaks to 0dB... Goldwave calls it "maximize")
2.  Use the compressor to "reduce loud parts"
3.  Normalize again to bring-up the average level.

Here are a couple of presets from GoldWave:

Reduce Peaks:
Multiplier -6dB (your "ratio")
Threshold -6dB
Attack 0.001 seconds
Release 0.001 seconds

Reduce Loud Parts:
Multiplier -6dB (your "ratio")
Threshold -15dB
Attack 0.1 seconds
Release 0.1 seconds






Dynamic Range Compression -- Settings

Reply #2
Dynamic range compression might help a little bit with making quiet sections more audible, but unless you're willing to put in some effort your music will probaly end up sounding awful. To get the results I presume you're after (radio-like even levels) you'll probably be better off with some sort of automatic gain control.
Maybe something like this:
http://devilswhisper.com/agc.htm
I have no idea how to use that particular plugin or if it's any good, it was just the first result of a quick google.

Compression really does need to be tailored to the track. Many CDs these days are already heavily compressed, meaning if you use the same settings on a range of different material, some tracks will sound decent, while others will end up sounding downright terrible. A track with a lot of headroom and only the occasional snare hit making the highest peaks can be compressed quite a bit without too much noticable difference (relatively speaking) to the original, whereas a balls-to-the-wall overcompressed track will just end up sounding like even more of a turd - background noise will be brought to the foreground, cymbal decay will be the same volume as the attack etc.. I know that's not what you want to hear, but that's how it is.

Dynamic Range Compression -- Settings

Reply #3
If you want it to sound like it does "on the radio", you'll need a multi-band compressor.

I don't think any of the free/cheap audio editors have one - I've faked one with filters and multi-track in Cool Edit Pro, but there are some nice (and not so nice) plug-ins for Winamp that do a similar thing. You can easily use the disk writer to apply the DSP to copies of your audio files.

There are probably some nice stand-alone apps too - I remember one DJ package had a nice multi-band DRC built-in, but can't remember which one.

Of course there are lots of pay-solutions, some of them costing rather a lot.


I'm surprised pop music is disappearing under the traffic noise - it's usually mixed/mastered to avoid this. It's classical music, jazz etc which usually suffers.

Cheers,
David.

Dynamic Range Compression -- Settings

Reply #4
I briefly looked into this and found a free program called SOX http://sox.sourceforge.net/ that can do this. There is a recommended command line to do this, but I tried it on 2 tracks and it produced severe clipping. I didn't look further into changing the parameters, but mabe someone with knowledge of this program can supply some assistance.

@2Bdecided
Can you recommend any Winamp plugins that you consider good?
Glass half full!

Dynamic Range Compression -- Settings

Reply #5
No need to do so much hard work for this.

Use foobar2000 with vlevel component. It's an AGC just as Dracaena wrote.

Adjust settings until you like what you hear, and use converter afterwards to modify files for your car. I just saved you many hours
Can't wait for a HD-AAC encoder :P

Dynamic Range Compression -- Settings

Reply #6
@2Bdecided
Can you recommend any Winamp plugins that you consider good?
Well, I've always thought this one should work...
http://www.hansvanzutphen.com/stereo_tool/
...but I can't figure out what I consider to be decent settings.

This comparison is way out of date, and I don't think they're multiband, but I liked Audiostocker too...
http://faq.arstechnica.com/link.php?i=1635
...the main advantage being it's trivial to set-up, and does the job. Try it.

I haven't tried the fb2k plug-in odyssey linked to, so can't comment on that.

Cheers,
David.


Dynamic Range Compression -- Settings

Reply #7
@2Bdecided
Can you recommend any Winamp plugins that you consider good?
Well, I've always thought this one should work...
http://www.hansvanzutphen.com/stereo_tool/

Umm, isn't that overkill considering OP's problem? Really, I don't think OP are after a DRC solution at all, judging from his problem. Sure DRC will boost silent parts, but in reality I think it damages audio too much. AGC will just boost the silent parts. Also it eliminates the need for replaygain, as it does it on the fly.
Can't wait for a HD-AAC encoder :P

Dynamic Range Compression -- Settings

Reply #8
Many thanks for your replies.

[quote author=2Bdecided link=msg=0 date=]
Yes, quite a few tracks have no problem; but take, say, Gentle Giant's "Think of Me with Kindness". I don't think it was mastered to avoid this issue.

[quote author=DVDdoug link=msg=0 date=]
Thanks.

[quote author=Dracaena link=msg=0 date=]
Thanks for the advice. Unfortunately, the AGC effect in that link is not available -- and, anyway, it apparently requires experimentation as well. I'm loath to spend any time experimenting with this, as I have the distinct feeling I'd only be re-inventing the wheel. Surely I'm not the first to put together a bunch of Deep Purple, Queen, Pink Floyd, ELP, etc, to play in the car...

[quote author=bilbo link=msg=0 date=]http://sox.sourceforge.net/[/url] that can do this.[/quote]
Great idea, sox; and I already had it installed. Under "Compander", soxexam suggests

Code: [Select]
compand 0.3,1 -90,-90,-70,-70,-60,-20,0,0 -5 0 0.2


I tried it on a few tracks and it didn't generate any clipping. We'll see how it does on the rest.

[quote author=odyssey link=msg=0 date=]
Thanks, I haven't used foobar so far, but I'll look into it. Incidentally, why exactly would AGC be better than DRC for this problem?

In the mean time, I found an Audacity plug-in/standalone app which is supposed to do precisely this job

chris's dynamic compressor


Dynamic Range Compression -- Settings

Reply #9
[quote author=odyssey link=msg=0 date=]Use foobar2000 with vlevel component.

Thanks, I haven't used foobar so far, but I'll look into it. Incidentally, why exactly would AGC be better than DRC for this problem?
[/quote]
Because it's simpler and doesn't compress the audio. DRC damages audio in that it reduces the dynamic range. I'm not all into the tech, but I'm fairly sure that when you apply DRC, you will not just with a high probability damage loud parts, but also the silent parts might have reduced dynmaic range. This is purely from memory, but once I played around with some compression settings in my favorite audio editor, and it seemed the silent parts also got a little flatter, than they used to, even though they are still not very loud (if you get what I mean). This could be for a number of reasons, and I'm not saying that all DRC's work that way, but generally I would avoid anything that has a possebility of reducing the dynamics.

That said, the content you are applying it to, probably wouldn't suffer much from it anyway, but newer productions (2000+), already has reduced the dynamic range to it's maximum, and trying to apply another DRC on top of it most of the time results in very bad clipping. Now with AGC, you won't suffer this problem, as the algorithm is much simpler and more suited for your situation. It won't damage your audio for sure - actually It's more like a "replaygain-on-the-fly" that will keep the loud parts as they are and just increase the volume for softer parts. Also I'm quite sure it would decrease the time used when you use the converter compared to any other DRC DSP.

You should just try it
Can't wait for a HD-AAC encoder :P

Dynamic Range Compression -- Settings

Reply #10
Any traditional compressor will reduce dynamic range. The noise floor is raised by the amount of makeup gain applied.

Dynamic Range Compression -- Settings

Reply #11
Stereo Tool has a multi-band compressor/limiter/expander.

I have never used the commandline version.  I think it would be easier to just use it with the winamp disk writer.  Just put your music in the playlist and hit play and watch it go!

And omg there's a verson3 now  gotta get it. (I only have v2)
Vorbis-q0-lowpass99
lame3.93.1-q5-V9-k-nspsytune

Dynamic Range Compression -- Settings

Reply #12
The noise floor is raised by the amount of makeup gain applied.

This is a natural effect of raising the volume  Happens with AGC also.
Can't wait for a HD-AAC encoder :P

Dynamic Range Compression -- Settings

Reply #13
If you want it to sound like it does "on the radio", you'll need a multi-band compressor.

I don't think any of the free/cheap audio editors have one - I've faked one with filters and multi-track in Cool Edit Pro, but there are some nice (and not so nice) plug-ins for Winamp that do a similar thing. You can easily use the disk writer to apply the DSP to copies of your audio files.


For the Mac users - the SlimSlowSlider 3-band compressor (http://www.kvraudio.com/get/950.html) is free and works well with any AudioUnit compatible app.  I use it to master some of my live recordings that need a little tweaking before committing to CD, and it can of course be adjusted to your liking.  As with any compressor, though, you can easily destroy a performance with aggressive settings.

Dynamic Range Compression -- Settings

Reply #14
An "Automatic Gain Control" (in the digital domain) is a form of Dynamic Range Compression.


The issue isn't gentle vs aggressive settings. You can easily have "gentle" settings (e.g. small change, slow change) that sound awful, and "aggressive" settings (e.g. large change, fast change) that sound quite effective. What you want ideally are appropriate settings for the situation, so that without comparison with the original, it just sounds "normal" and you can't hear the DRC "working".

Sadly "one size fits all" isn't possible across all possible sources - different dynamic ranges, different musical styles etc require different attention. However, you should be able to find one setting that works well enough for the kind of tracks you're looking at. At least you're no trying to music rock, jazz and classical.

Cheers,
David.

 
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