Calibrating Audacity

One thing I forgot to mention from the weekend was the way I calibrated Audacity's latency compensation. The current stable version, 1.2, does a pretty good job of synchronizing newly-recorded tracks with what was playing when you recorded them, but it's not perfect and not adjustable. The new version, 1.3, has adjustable compensation. Unfortunately, what comes out of the box is practically unuseable -- there's a huge lag, and at first I compensated by time-shifting the new track by hand, which is obviously highly error-prone.

So Saturday afternoon, before I did any actual recording, I calibrated it. I recorded a dozen seconds worth of clicks (by tapping my guitar's pick guard with a fingernail, which gives a nice sharp attack), then cranked the volume up and recorded a track with the appropriate earpiece of the headphones held up close to a mic.

I still had to amplify the resulting track by 30dB in order to actually see the resulting waveform -- headphones are meant to operate in a small, closed volume. But it worked. (Note: "amplify" is the first or second on the menu of built-in effects.) (Hint -- vary the click pattern so you can see which direction you have to adjust.)

The way you get the exact timing between clicks is to zoom way in and select the gap. Set the selection display at the bottom of the screen (another new Audacity 1.3 feature) to show the selection length in milliseconds.

After a little trial-and-error, I found that the correct latency compensation for my setup was -140ms. There's also a buffer parameter which defaults to 100ms; I cranked it up to 200. Don't know whether I had to or not, but it seemed like the right thing to do.

Q.E.F.

tracks, and so on

Fixed many of the problems with this morning's dump CD; revised four tracks in all. Mostly just levels, though fixing "Uncle Ernie" involved going back to before I damaged it with too much eq. Sounds better without, I think. Still a couple of timing oddities -- singing against a scratch track is hard if you haven't done it much. I'm getting better, but...

I haven't been getting much work done, but the situation is gradually improving. Spent most of the afternoon reading our annual research report and chasing links to some of the technical reports. Fascinating reading; I had one idea that looks as though it'll turn into a tecnical report for next year. Nothing like getting an early start.

The weather seemed cold and damp, and the forecast included rain, so I skipped my usual walk and went to Fry's, chasing a 400GB Seagate SATA drive advertised for $100. I've heard fewer complaints about Seagate than Maxtor recently; now I have one of each and upgrading my main fileserver is going to be much simpler -- I'll just double my existing partitions. My main drive, currently a 200GB, is 95% full in the main partition. Audio and a Debian partition will do that.

( You probably don't want to know about my plans for the old drives )

Sure enough, it was starting to rain as I was leaving Fry's. If I'd gone out for my usual 1-hour walk I would have spent the last 20 minutes getting wet.

Ordered another isolation transformer, a mic stand bag, and a couple of other items from Musician's Friend. Free shipping for orders over $99.

I'm starting to get fuzzy around the edges. Time for bed.