Topic: peak lowering in audacity

[Brian Skalinder]

Don't expect the compressor to reduce signal all the way down to the threshold -- that's basically a limiter's function (and it generally doesn't sound very good).  Theoretically, a ratio of 10:1 should knock down a signal 10 dB above the threshold so it's only 1 dB above the threshold.  You're running into an issue I discovered long ago:  the compressor doesn't compress the signal as far as I expect.  This is true in all the compressors I've used (Audacity, Audition, WaveLab, Samplitude).  They knock down the signal, but not all the way to where I expect based on the settings.  I've not taken the time to explore the issue more deeply, and have simply assumed there's some limit in the implementation, whether related to the attack, release, or internal workings, that makes it so.  That said, I still find compression very useful sometimes.

You might try applying compression only to the problematic peaks.  This will allow you to use a more aggressive threshold and ratio without impacting the rest of the recording.  And if compression isn't accomplishing what you need, you might try using a volume envelope.

[DisturbedPyro]

it just seems weird to me that will all the in depth functions these audio editors can do, there isnt one that works like a hard limiter but rather than just hacking off the peaks at whatever designated limit you enter, it instead reduces the peaks to that level. so that it would be as if you had manually lowered the peaks using a negative amplify

what ive always done in the past is: i find a peak, select it, and then lower the peak by entering a –x db amount to bring it down to more of an appropriate level to match the rest of the recording. its a pain to go through and find all the peaks so i figured with all the hundreds of effects you can use on a recording, theres got to be one that allows you to enter a designated point at which any peak above that number would be reduced to that level. is there really no way to do this?

[Brian Skalinder]

A compressor or limiter is the only tool I know of that works the way you mention.  The limiter does so in a bit of a harsh way, and the compressor -- by design -- is more subtle, so it doesn't flatten out the waveform.  But it also doesn't reduce the level quite as efficiently, either.  I stopped searching for alternatives because I've found mild (or mild or heavy) compression works just fine for those instances I need it.  I like dynamic range and don't want to squash it too much, so I've never searched for an alternative tool.

[DisturbedPyro]

so i guess im s.o.l. ok, thanks for the help anyway. id anyone else has another idea, please let me know

[Brian Skalinder]

I don't know if your SOL, yet.  Try multiple passes of the compressor, but with a higher threshold so you're not impacting most of the audio.  You might also try a pass or two of compressor (again with a higher threshold), and then a limiter pass for any remaining pesky peaks.  Or one or both of those + a final pass with a volume envelope on any particularly pesky peaks.

Just for curiousity's sake, and to get a better handle at the peaks we're talking about, would you post a screenshot of the entire performance's waveform, using Audacity's dB scale?

[Scooter123]

In Goldwave, this is stupidly easy.  They even have about 10 presets for this.  I looked at the presets and made my own.

Pick a threshold minimum and maximum and it reduces the volume of those portions across the whole track or within a selected area, like a few seconds down to the minimum.  It does not touch the volumes below of the spread you've selected.  You can raise or lower that spread of db to suit your taste.

Goldwave also has the reverse, which takes lower db sections, again within a range and boosts that spread within a track or a selection within that spread only, so quiet piano parts are boosted but loud cymbal crashes are not.

What I do is a batch file processing, compressing the volume at a very high db level, so it is not very noticeable at all, then the reverse ever so slightly, then compress again etc.  With Goldwave, I can take a whole 2 hour show and program the batch commands, multiple light compression, boosting, compression boosting etc, and it processes the file overnight and even saves it.  So in the morning, I'm ready to look at it one last time for tweaks and file splitting. 

 

[db]

"a" and the pop just after 45 mins looks like the only thing you'd want to alter. can you envelop or pencil tool these away?  if not, i'd let it slide. the waveform looks fine. the thing to consider with compressing a whole mix (as was pointed out above) is that you can lose more than you gain (pardon the expression). it's a taste/opinion thing, but i find compression useful for recording drums (overheads/snare), bass.. etc. individual instruments in a controlled studio setting. applying it to a live recording has more downsides than up as you are killing whatever dynamic range you've collected.

[Brian Skalinder]

In Goldwave, this is stupidly easy.  < snip >

I haven't touched Goldwave in years and years, but sounds like every other implementation of compression:  easy, really.  Just a matter of finding what works for you.  Though I'm not sure Audacity supports batch processing, I know other apps do.

If the waveform db quoted is of the whole show, I agree A and B + the peak a little after 45min might be the only places I'd bother tweaking.  You might apply a volume envelope to reduce the levels of the first 7 minutes or so -- it looks like maybe you tweaked levels to lower them a bit after this portion -- but if this section of the performance was naturally louder, I'd just leave it alone.

Still curious to see the whole waveform in dB scale, if you're willing.  It's a better representation than the arbitrary 0.0-1.0 scale.  Either way, hope we can help you find a resolution that makes you happy. 

[DisturbedPyro]

In Goldwave, this is stupidly easy.  They even have about 10 presets for this.  I looked at the presets and made my own.

Pick a threshold minimum and maximum and it reduces the volume of those portions across the whole track or within a selected area, like a few seconds down to the minimum.  It does not touch the volumes below of the spread you've selected.  You can raise or lower that spread of db to suit your taste.

Goldwave also has the reverse, which takes lower db sections, again within a range and boosts that spread within a track or a selection within that spread only, so quiet piano parts are boosted but loud cymbal crashes are not.

What I do is a batch file processing, compressing the volume at a very high db level, so it is not very noticeable at all, then the reverse ever so slightly, then compress again etc.  With Goldwave, I can take a whole 2 hour show and program the batch commands, multiple light compression, boosting, compression boosting etc, and it processes the file overnight and even saves it.  So in the morning, I'm ready to look at it one last time for tweaks and file splitting.

yes! i like goldwave's compressor much better. i used the "reduce peak" preset and it gave much more of the effect i was expecting. it also did more of what you all said a compressor should do...im not convinced audacity's compressor works as its supposed to. anyway, i like goldwave's much better, so i can just use the preset as a starting point and alter it from there to get the results i want. as always, the experts at tapers section know their stuff. thanks scooter for the goldwave suggestion. and thanks to brian for sticking with me this entire time! you guys rock!

[Brian Skalinder]

Perhaps Audacity's compressor still isn't fully functional.  Glad you tried another option and it worked for you!