How to edit the level to not exceed a maximum limit?

I am importing an audio file from Final Cut Pro. The TV station says we cannot have any audio going over the -12 db levels to avoid digital audio clipping. Is there a way to use Audacity to import the audio file than capping all the audio levels above -12db without changing the levels of the lower audio sounds?

I am told Normalizing changes all the levels. Compression evens out the high and low levels. But neither can edit the audio levels above -12db.

I have an old Vision Software called Opcode and I remember Opcode having the ability to change the volume of the MIDI notes to what ever you set. Including the ability to only edit the notes above a set number - then take those midi notes and change their values. Can Audacity do this with audio levels above -12 and lower only the levels above -12db?

Thank you,

I’m surprised that the TV station does not do this for you, but yes you can do it in Audacity 1.3.

To limit the peak level to -12dB while keeping quieter sounds at a reasonable level is in 2 stages:

  1. Use “Chris’s dynamic compressor” to even out the peak levels and raise the volume of the quiet bits.
  2. Use the Amplify effect to set the maximum level to -12dB

You can get Chris’s dynamic compressor from his web site:
Right click on the download link (where it says “Download the plugin source”) and save the file as “compress.ny”
Copy that file into your Audacity plug-ins folder (If you are using Windows, look in the C:Program Files directory)
Restart Audacity and it will be listed in the Effects menu as “Compress dynamics”.
Set the compression amount to about 0.7 and apply. (This can be very slow on long tracks if your computer has insufficient memory - if you have this problem you will need to process the track in sections. If you need to do that, try and find a periods of silence for where to start and end your selection). Leave all the other settings at default.

Open “Amplify” from the Effects menu and type “-12” (without quotes) into the “New Peak Amplitude” box (don’t forget the “minus” sign) and apply.

How do they manage to play CD’s or DVDs on that station? They are usually normalised to 0dB (or very close to 0dB).

Thanks Steve.

I went to the link, downloaded the “plugin” but it comes out as at compress.ny.txt and does not load up in Audacity. I placed both in the plug-ins folder as well as the Audacity 1.3.8 folder but with no results - neither loads up under the Effects menu in Audacity.

There shouldn’t be a .txt suffix but no matter how many times I download it always comes out with the .txt

I am on a iMac, OS 10.5.7 system.

Is there something I am doing wrong?

This is a Nyquist effect. The file is actually just a plain text file (you can open it in a text editor and see the code).
When placed in the Audacity plug-ins folder, Audacity is able to read the contents and run the script to produce the effect, but to do this it needs to recognise it as a Nyquist script. That’s what the “.ny” extension does - it tell Audacity that it is a Nyquist script.

Your computer is “helpfully” renaming the file and adding a “.txt” extension because it can see that it is just a plain old text file.
Just rename the downloaded file (take off the “.txt”) so that it is just “compress.ny” and put it in the plug-ins folder.
Audacity will need to restart in order to find it.

Sorry Steve,
Removing the .txt made no difference and it still doesn’t recognize the compressor. I made two copies and placed on in the Nyquist script folder as well as the Plugin folder, restarted Audacity and still it doesn’t show up in the Effects menu.

I think there is something wrong with plugin downloader on the link website. That’s where it starts and downloading a .txt file.


Does your computer show the file extension of all files?
If not, can you set it to do so (I don’t use Macs, so I’ve no idea how to do that. - Google it if you need to).

I’m pretty sure the download is OK - I downloaded it myself a couple of days ago and it was fine, and I’ve just checked again now and it’s still fine.

An alternative way to download the file (this works with Firefox and should work with other browsers).
Instead of Right clicking on the link, just click on the link and it should open as a web page full of text.

The text starts off with

;nyquist plug-in
;version 1
;type process
;name "Compress &dynamics..."

Now go to the File menu of your browser and save that page as “compress.ny”

You don’t need a copy in the Nyquist folder - just the plug-ins folder.

Which version of Audacity do you have? I’m not sure if this plug-in works with Audacity 1.2.x

If you have ever had a previous version of Audacity installed, check that you do not have more than one Audacity program folder - if you have, you may be putting it into the wrong one.

Or you can do what most of us in Final Cut do and reduce your overall level 8dB and call it done.

If you have natural, normal (no clipping) levels in Final Cut, you are using the consumer DV sound levels which use a tone standard of -12. If you put Bars and Tone on your timeline from the effects tab, the tone level will settle at -12.

Broadcast standard is -20. Bump everything down 8dB with the audio level controls and ship it.

I wish Chris wouldn’t do this, but installing his plugin is a lot harder than it should be. If you select his work from the web site, your screen might fill up with programming and text. Select-All > Copy and Paste it into a Text-Edit (set to plain text – that’s important) and force it save as compress.ny.

I’m surprised that FireFox didn’t offer to File > Save Page for you and create the file. That works for me.

Copy that file into the Plug-Ins folder and it should show up as “Compress Dynamics” in your filter list.

That, too, is a lot more cryptic than it should be. It’s a good thing that plugin works really well… By the way if you do this to natural DV sound levels, the problem is going to get radically worse, not better. Chris will pump your sound up much louder instead of settling it down to -20.


A word on tone levels. Tone was important when VU meters ruled the world, but now it’s just a generic reference tag and not as useful as it was.

In digital video, show sound routinely peaks about 10dB over tone level. So In consumer DV, the show peaks just shy of overloading.

In Broadcast, the same thing happens, but since you’re starting at -20, the show peaks around, oddly enough, -10. Most of the show peaks around -12.

This is a little thing I recorded to illustrate the difference.


Don’t destroy your show sound just to conform to broadcast standards. The only difference between you and them is 8dB. This kills Final Cut people all the time. Your track doesn’t have to live at zero like an Electro Trance Dance Mix.



Chris’s Dynamic Compressor plug-in lives here now.