Photography Blog | South | Africa

(Part I is here)

In Praise of Adobe Audition

By Ctein

As we resume...

I had digitized all 500 licorice pizzas and saved the resulting WAV files to duplicate external hard drives. Unfortunately, because of hardware/software glitches and ticks and pops in the records, I really had to listen to every transcription all the way through to make sure it was okay before I got rid of the record.

I like listening to music when I'm pixel-pushing on the computer. It turned out, pleasant surprise, that I still like 98% of what I bought decades ago. Newer tastes have expanded my musical enjoyment, but they haven't evicted the old ones. And, of course, much of the music had pleasant memory associations. Listening to 300+ hours of records took time, but it wasn't onerous.

What was onerous was doing the audio cleanup. Most of the albums were in pretty good shape, with only a handful of transients. When I would hear a tick or pop, I'd switch from Photoshop to Audacity, zoom in on the defective waveform and use the fabulous Repair tool to make it go away. Those little interruptions added about a third to the actual listening time; not a big deal.

Sadly, many albums had a lot more than a handful of problems. By way of example, here's an especially bad track (note: the wav files are about 60 MB each). Some were just inherently noisy, some had acquired too many scratches over the years. Whatever the reason, when there are dozens or hundreds of audio defects to repair, it becomes unreasonably time-consuming. Also not something I can do as a background task; the interruptions to work come too fast and furiously.

Consequently, after over two years I still had almost half the files to clean up and they were worse than what I'd completed. I was feeling frustrated. All the cheap/bundled-in click and pop filters I tried worked like they were running a lawnmower over the waveforms, chopping off peaks. They don't actually remove the noise they find, and at sensitivity settings high enough to be useful, they do major damage to the sound quality. They suck.

I found software packages out there that serious audio folks considered pretty good at this task. Problem: They all cost money, some into four figures. Most didn't have trial versions, being aimed at professionals who already knew what they needed. Then I discovered Adobe Audition 3 as a field-trial beta download for the Mac. I could try it for free. It rocked.

Now it's out as Audition 5.5. Fabulous. Although it's $350 it would've been worth every penny to me to get it the moment I embarked on this project. You can check it out for yourself for free for 30 days with a fully-functional trial download.

Audition is a full-blown audio production tool. You can use it to record, mix, edit, and master multitrack recordings (it can record from my Inspire 1394 with no hassles). I'm using a miniscule fraction of its capability.

This illustration shows my master panel. Top left is a listing of open files. Audition will let you queue up operations on different files and then run them as processor cores become available. Audition is multicore savvy and very fast. On my quad-core iMac, it can perform operations on three files simultaneously and process albums almost as fast as I can queue up tasks—typically it's one or two minutes to run an operation like click removal or noise reduction on an album.

At the bottom right are the history states. Like Photoshop, you can undo or revert to any previous state. There's primitive scripting abilities (maybe it has sophisticated ones I haven't found yet); I can record a series of operations and save it as a "Favorite" that I can call up or apply to batch process a bunch of files.

The first thing I do on an audio file is run Automatic Click Remover (under Effects/Noise Reduction) twice (the ACR panel is open in the illustration above). Sometimes a second pass catches a few transients the first pass didn't. I've made this double-pass a Favorite of mine so it doesn't take any more effort on my part; in fact it's easier, because it's now at a higher menu level. You can save custom control settings as a preset, but the default settings work just fine for me. Almost every tick and pop is eliminated and I can hear absolutely no difference in the quality of the resulting audio, even with electronic music and percussion that has sharp transients of its own. I ran ACR twice on my sample track, and the result is here. No, it's not perfect, but the original was pretty hopeless.

The last thing I do is reduce the background noise—any residual hum from the ground loops (almost none), turntable rumble, vinyl noise—with "Noise Reduction (process)." I use a customized frequency weighting (see below) that hits the lows more than the highs, as that's where most of my noise is. I capture a noise print for each album (occasionally, each side) by selecting a small portion of the recording at the beginning of the file or between tracks.

I usually run noise reduction twice at low strength; the very helpful folks in the Adobe Forums suggested I would get better results if I shaved off the noise in a couple of passes rather than trying to hit it all at once. You can hear what that does to my sample track by downloading it. The cleanest albums only required a single pass; a few exceptionally noisy ones required three, with new noise prints between each pass.

The best thing about this tool is the preview. Hitting the play button in the lower left of the panel starts running the filter on my audio without actually processing the file. I can move the time cursor all over the place to sample different parts of the album and make sure I like the effect. Super-cool is the "Output Noise Only" checkbox, that plays only what's being filtered out, so I can hear what I'm shaving off of the real music. That almost never proved to be a problem, often it was truly inaudible. Usually it was only at the low frequencies, in other words a slight deemphasis of the bass, easily corrected with equalization.

The peaking VU meters at the bottom let me see how much noise is still making it through. Without putting any real effort into fine-tuning, I could routinely get the mean noise level down between –55dB and –60 without any audible change to the music and sometimes into the mid-60s. The results of this two-stage process sound so much better than anything that ever came off of my turntable "naturally" that it amazes me.

Audition includes special functions for eliminating 60 cycle hum and its harmonics and for eliminating hiss. Neither of these were problems with my vinyl, but I expect that hiss removal will prove mighty useful when I get to the tape cassettes.

Average time I spend per album in Audition is under 10 minutes. I'm reprocessing all the files I did manually before I got Audition, and I'll be done by the time this column appears.

I've found one minor bug so far: the first time I call up my custom noise reduction preset, the graph shows a clearly-wrong frequency weighting curve. If I go back to the default preset and then pull up my custom preset a second time it loads fine.

Peculiarly, Audition can read flac files but it can't write them. I use Audition to process my digitized vinyl and save it as wav; then I open that up in Audacity and play it to check the quality and catch any glitches that may remain. The majority of Audition-cleaned files play straight through with no artifacts that need my attention. From there I save it as a flac file.

All things considered, though, I am so happy I discovered Audition.

Now there are my 100 cassette tapes, for which Audition will be a godsend. As for my 750–1000 hours of VHS tapes? Done last year. That's a subject for some future column.

Ctein

Ctein's next column(s) will begin a series called "Introduction to Digital Printing." The schedule has been mixed up because of Yr. Hmbl. Editor's recent vacation, but starting two days from now Ctein's column will re-alight on its regular Wednesday perch.

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Original contents copyright 2011 by Michael C. Johnston and/or the bylined author. All Rights Reserved.