absolute time of recording

[Axel_]

Hello,
can one of the audacity gurus pls give a quick answer to a stupid question:

Audacity recordings work with time relative to the beginning. Is there a way to get the absolute time of a point in a recording?
Is there a recording option doing this?

(Application: alarm recordings)

thanks

[kozikowski]

Audacity doesn't make a very good surveillance recorder.

-- As you discovered, there's no good way (outside of SMPTE Time Code) to record time of day.

-- We can't do Rolling Recording (erase the old while you're recording new).

-- There's no good way to custom Timed Recording. There's Sound Activated Recording, but we can't go into full record for a defined period.

-- Audacity doesn't Play Well With Others, so for best stability you can't have any other applications running on the machine. This brings you immediately to buying a real Surveillance Recorder instead of trying to cross-purpose Audacity.

-- Audacity doesn't have guaranteed process integrity. Search the forum for "holes or gaps in my recording."

-- There's no company here. It's a bunch of volunteers and we can't do law enforcement, traceable surveillance or certified evidence.

Koz

[kozikowski]

That's not to say you can't do this cheaply. Run a video camera watching a clock and recording the sound event. That may take you straight back to buying a surveillance system rather than trying to wing it.

Koz

[Axel_]

thanks for your reply, Koz. I understand, this is not the purpose of audacity.
Actually, we are a bunch of glider pilots and want to monitor our frequency. The sound triggered recording would be perfect, if only we knew when it was triggered.

thanks again for your great program!

[kozikowski]

Sound Activated Recording only activates when the sound is there. You can't use the trigger to start and then tell it to record the next ten minutes.

SMPTE is not a dreadful way to do this. There are SMPTE generators/readers. It will take up one channel of a stereo recording for time and you can do whatever you want with the other.

~~

Never mind. They're all in the high hundreds of dollars.

http://www.markertek.com/product/es-453 ... e-displays

The attached clip is of SMPTE sound. It was designed to go on the low quality cue track of early tape machines...and survive. Early tape had your problem. No time.

http://kozco.com/tech/audacity/clips/SM ... oShort.wav

Cover your ears.
In fact, if you snugged a time code reader up to your computer and played that track, the reader would tell you the exact time I recorded it down to television frames, 1/30 second.

Maybe there are software versions of these generators/readers. DV Home tape machines didn't use the full timecode. They used frame-code, a simplified version. So that's another possibility.

None of this is going to work if you need both stereo sound tracks.

Koz

[kozikowski]

There are silly/stupid ways to do this, too. Record a radio tuned to NBS Fort Collins.

"National Bureau of Standards, Fort Collins, Colorado. When the tone returns, the time will be Four Hours, Thirty Minutes."

Boop.....Boop.....Boop

If they even still do that.

I know there used to be a Canadian one—in French, thankyouverymuch. I used that one because the reception was better.

You can work the recorded time back from there.

Koz

[kozikowski]

Still there. See, I wasn't joshing. My radio only picks up the 15MHz broadcast and I live in a festival of overhead wires and electrical interference. But still.

https://en.wikipedia.org/wiki/WWV_(radio_station)

So, you put that as a mono recording on one Audacity track and you put your work on the other. As long as the "show" lasts longer than one minute, WWV will be happy to time-tone align you.

~~

There's the Canadian one.

https://en.wikipedia.org/wiki/CHU_(radio_station)

I can't hear that one because my receiver won't tune all the utility short wave frequencies.

Koz

[steve]

Audacity recordings work with time relative to the beginning. Is there a way to get the absolute time of a point in a recording?
Is there a recording option doing this?

The next version of Audacity is due to be released around the end of the year, and has an option to automatically add the date and time to the name of newly recorded tracks. (The "start time" of the recording). The setting will be in: "Edit menu > Preferences > Recording" and the feature will be documented in the manual.

[kozikowski]

Is there a new time window on the bottom that reads forward from that tagged time? Ver 2.1.4? Where does it get the time from and can I set it?

Koz

[Gale Andrews]

Is there a new time window on the bottom that reads forward from that tagged time? Ver 2.1.4? Where does it get the time from and can I set it?

It's in Recording Preferences. It will be in 2.1.3 when released.

It gets system date and time and writes it in ISO format (file name safe, not configurable).


Gale