Audacity Forum

Hi, I'm new here and have used audacity to solve problems at work. I have been able to record audio from our analog 2way radio networks with this program. Can audacity record a min. of 100 hrs continuous and is there a formula or chart for estimating hard drive space and recording time? I use XP and vista. Thanks
acomtech

I'm going with no. I think the limiting factor is storage, and not just size. Audacity needs clean, fast, error-free places to put its work and it needs it in a timely manner. Sooner or later, the drives are going to fill up and change characteristics. It's the characteristics that kill you.

Surveillance systems almost all compress very strongly before they commit the work to a drive or other storage medium. Audacity doesn't do that. It's shoveling live segments to the drives all the time it's recording and the best you can do is reduce the quality of the work to make the process a little easier.

Then there's the damage problem. Hour 99 and the computer feels a very serious urge to wee behind the bushes and drops a segment or two. That's the end of 99 hours of recording. People are stunned to find out how long it takes to recover a crashed hour or two long show. Doing it at 99 hours is worth buying another computer to do the next capture because this one won't be done in time for the next performance.

So the theory is there, but the theory is based on perfect computers and storage systems. Even Dell doesn't make those.

You are describing a surveillance recording system designed to do this. The good ones can juggle multiple streams in record and playback at the same time.

Koz

Oh, the original question. Roughly 700MB per hour for an hour long show at 44100, 16-bit Stereo. Many operating systems start having file management problems at 2GB and 4GB, so there's that.

You posted in the Windows forum, but I would so be doing this with a modern Mac. FireWire management of a 1TB external hard drive and well behaved, multi-tasking operating system. Even at that, there may be problems with one stunningly enormous sound file.

Koz

acomtech wrote:Can audacity record a min. of 100 hrs continuous

I believe the record so far is 3 months continuous, but the person that achieved that had quite a job doing so and in the end wrote his own program that could write a sequence of smaller audio files direct to disk in real time.

There is a limit to the maximum size of a WAV file - 4GB (although some Windows computers limit this further to 3, or even 2 GB).
Audacity 1.3.x can theoretically handle files of any size, but in practice it is another issue. Can your sound card run rock-solid-stable without dropping a byte continuously for 100 hours? I don't think that I would like to trust XP or Vista to do anything continuously for 100 hours unless I set up a dedicated computer to do the task (and then I would probably use a custom install of a NIX operating system rather than Windows).

If the audio is silent (or almost silent) for the majority of the time, you could use the "Smart Recording" feature in Audacity 1.3.7 so that Audacity only records when there is an audio signal (above the "silence" threshold that you set). This could massively reduce the length of the recording and make it a lot more manageable.

acomtech wrote:is there a formula or chart for estimating hard drive space and recording time?

For CD quality stereo - it's about 10MB per minute. (a 600MB audio CD is about an hour long).
If you drop the quality down to 22050 Hz sample rate mono, then you are down to about 2.5 MB per minute.

To contrast that. We recently installed a six channel, high definition, h.264 television surveillance system that will keep a month of continuously cycling storage on relatively modest hard drives and make it available to several people at the same time with web access. The box was obviously built to purpose.

So yes, you could probably force Audacity to do your task...once.

Microsoft makes an excellent memory checker. Don't let the title of the page put you off.

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

This tool loads its own modest operating system (particularly modest if you can boot from a floppy) and beats the crap out of your memory stack using multiple different tools. The rest of the computer has to be in terrific shape to pass these tests because any dropped test anywhere for any reason will cause the process to fail. Run that test continuously for a couple of days.

Many computers won't make it and neither will your recording chore.

Koz

Thanks for all your comments. It appears that a commercial logger is the path I will have to take. As I study more about audio files and editing I find it very fascinating, and will be a great addition to my work in RF communications. I look forward to reading more on this forum.
acomtech

acomtech wrote:As I study more about audio files and editing I find it very fascinating, and will be a great addition to my work in RF communications. I look forward to reading more on this forum.

Even if Audacity is not the best tool for the job in hand (which is probably the case), download it anyway (the 1.3.7 version/ 1.3.8 when released) and have a play with it. It's free, fun, and a great way to learn a lot about digital audio.