Adjusting Compressor's Settings: DVD Audio

By Alex on December 11, 2008 10:00 AM | Permalink | Leave a Comment(2) | TrackBacks (0)

You can find more compression settings articles in our Supercharging Compressor series index.

If you read our Final Cut to DVD tutorial, you may be wanting to dig a little deeper into the belly of Compressor. I'll be writing at some length about the video settings in the coming weeks, but for an introduction, let's tweak a setting that's pretty noncontroversial.

Background (skip to Step-By-Step)
Out of the box, Compressor's DVD presets apply fairly aggressive dynamic range compression (see also) to your audio. If we were only talking audio, we'd call this transformation simply a compressor -- but to avoid confusion, I'll call it a DRC for this article.

In a nutshell, the DRC makes the loud parts of your audio quieter and the quiet parts louder, for a more consistent level of sound on your viewers' TV sets. To be fair, DRCs are popular in broadcast media, they're often appropriate for audio that's being delivered specifically to TV sets, and Compressor uses a really solid algorithm from Dolby itself. On the other hand, audiophiles loathe DRCs, and Compressor's default DRC algorithm is designed for movie theaters rather than DVD players. If you haven't spent time mastering your audio tracks, you might be pleasantly surprised by the DRC's effects when you prepare your DVD -- but then again, you might not.

Personally, I hate surprises -- and when Compressor substantially modifies my audio without my say-so, I get a little annoyed. So whether you want to turn the DRC off or just play with its preset values, read on for the (really quick!) step-by-step.

Step By Step

After you've opened Compressor, find the settings you want to use as a starting point. In this case, we'll use DVD 90 Minutes from the Apple Default Settings.
When you've selected the settings that you want to tweak, click the hard-to-find Duplicate button at the top of the Settings tab to make a copy of those settings.
Double-click on the specific set of settings that you want to modify. In this case, we want to change the audio settings, so double-click on the Dolby Digital Professional 2.0 item.
The Inspector window shows the settings that pertain to what we're modifying. Right up front, we see a summary of all of the current settings. Consider changing the default name and description to something that will help you identify this group of settings later.
The group buttons at the top of the Inspector let us change actual encoding settings. Click the Encoding group button.
If you want to remove the DRC that I described above, you'll want to change the Dialog Normalization on this page from -27dBfs to -31dBfs. Then, click the Preprocessing tab, and change Compression Preset to None.
Click the Save button at the bottom of the Inspector window, and your brand new settings are all ready to drag onto a source file!

Just as a reminder: later in this series, I'm planning to do some serious testing on Compressor's MPEG-2 (i.e. DVD video) encodes -- if you have a favorite set of MPEG settings that you swear is the best for your kind of video, I encourage you to share it so that we can put it to the test!

PS - Remember, we just turned comments back on ... please feel free to leave one.

Purple Tentacle said:

Thank you so much for this! I was pulling my hair out trying to figure out why Compressor was screwing up my audio that I had just spent hours mixing...!!

December 11, 2008 4:07 PM

Anonymous said:

Thank you! I read your article awhile back, but wasn't sure that it applied to me. But I was just watching a DVD I made with Compressor and noticed that when the crowd cheered loud, the music dipped. What the?! I realized it must have been the darn DRC! I used your tip and the music doesn't dip now. A relief.

November 12, 2009 3:50 PM