Re: visually scan audio spectrum

[kozikowski]

We try to keep dialog on the forum so the most people possible can benefit.

In a word, no. Audacity doesn't do anything in real time except capture/record. Also, while Audacity will cheerfully try to record for hours, the requirements of the computer become onerous as to be unusable. We've had a number of postings like this: "My recording went toes up. How can I recover my 13-hour show from twenty-seven million temporary files?"

I don't know of anybody who ever did the research of what it would take to record a continuous, high quality stereo show for 24-hours.... Let's see. Put down the four and carry the one. Safety factor 10%...plus the UNDO buffers...Divide by...

I get about an 60GB hard drive on a machine that's not doing anything else. No internet, no email, no browsers, no virus checker, no firewall, and surgically clean and defragmented. I would certainly also, given a Windows machine, run a memory checker continuously for a day or so to make sure my machine has no instabilities whatsoever. Linux machines have the reputation of remaining stable for weeks, but not so Windows.

Mom? What does it mean when my screen turns blue with tiny white lettering on it?

http://oca.microsoft.com/en/windiag.asp

So those are the fuzzy, rough numbers--and that's assuming a very high quality, 48000, 16-bit, Stereo show for 24-hours. I don't know of anybody who's ever tried it for that long, but then I don't know anybody compulsive enough to prepare a machine like that, either.

Koz

[kozikowski]

Oop. Forgot one. There's the 4GB limit on WAV files, too. So even if you do capture all that, you'll only get to export it in chunks (which you probably want to do anyway).
Koz

[steve]

I want to position a directional Mic. towards wildlife habitat's and let the recorder run for hours. there will be much inactive time on the recording.I want to visually inspect the audio spectrum for active moments without having to sit through house of listening.

Audacity 1.3 is probably a better bet than 1.2
"Edit menu > Preferences > Audio I/O tab > Record 1 channel (mono)"
"Edit menu > Preferences > Quality tab > 44100Hz / 16 bit"

Exit the preferences and hit "Record"
Click on the "Zoom Out" button a couple of times.

When the recording cursor gets to the end of the screen the track will jump to the left to make room for more recording. The zoom level will determine how much recording time you can see in one go.

In this screenshot, you can see a load of silence, and a bit of activity at about 6 mins 20 seconds.

screenshot.png (45.11 KiB) Viewed 495 times

(Not wanting to confuse you, but this screen shot shows a stereo recording, not a mono recording).

With these settings you should be able to get around 12 hours recording and export to WAV and be just under the 4GB limit for WAVs. For long recordings like this it is essential that you have a very stable computer with lots of unfragmented disk space, and nothing else running on it. (No internet, disable Windows Update, disable your anti-virus, disable screen saver and power saving). Export the recording as a WAV file as soon as the recording is complete.

Audacity 1.3 is not limited to 4GB recording time, but many computers will loose the plot at this point.

There are a lot of tools in Audacity that will help you to clean up your recording, delete the silent bits, and so on.

It's a free open source program, so it will cost nothing to try it. Practice on shorter recording before going for the marathon.

[kozikowski]

Yes, but.

44100 is widely considered barely up to serious music and may not be enough for critical sound work. That's why I picked 48000, the video sound standard. Also, my numbers are to calculate the required drive space, not the show size. The instant you Export as a self-contained WAV file, the required space doubles and goes up three times if you decide to do a little production and the system has to create an UNDO service. Then there's Windows. Remember Windows? That's going to need a gig or two to make it happy. Adjusting for mistakes, that's still over 16 GB of drive space needed to get that 12-hour mono recording out the door.

It's difficult to be too pessimistic about the machine needed to do this trick. I've been a party to recording critical performances in the face of a noisy environment and I can tell you it's vastly easier to understand the speaker if the recording is in stereo rather than flat mono.

I didn't think either Audacity had any capture limit. You get killed when you export. I'd be putting a label about every hour or so (tune as needed) and use that as the dividing line.

Koz