First-In-First-Out' (FIFO), fix length recording

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First-In-First-Out' (FIFO), fix length recording

Permanent link to this post Posted by goesproto.call » Tue Mar 07, 2017 6:28 am

As an amateur radio operator, I and several others I know in the fraternity, like to record our "on-air" communications for review.

I am currently making use of your audio editor software, truly a terrific program. The only additional feature I would suggest is a recording loop capability, i.e, a data file of specified time frame and sample rate that continually overwrites itself. Think of it as 'First-In-First-Out' (FIFO).

In example, if one chooses a recording duration of 1 hour... after the first hour and a half the created data file (be it .au, .WAV, etc.) would consist of the last half of the previous hour plus the first half of the following hour.

Please let me know if this feature already exist and I overlooked it, or there are work arounds to achieve the same effect.

Thank you.
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Re: First-In-First-Out' (FIFO), fix length recording

Permanent link to this post Posted by kozikowski » Tue Mar 07, 2017 10:04 am

That would be the "surveillance mode" that Audacity doesn't have. It won't on-the-fly time stamp, either.

You would think there's no down side to those features, but you haven't had to deal with people trying to use Audacity for legal actions and law enforcement.

Koz
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Re: First-In-First-Out' (FIFO), fix length recording

Permanent link to this post Posted by steve » Tue Mar 07, 2017 10:12 am

goesproto.call wrote:Please let me know if this feature already exist and I overlooked it,

No, this feature is not available in Audacity, so I've moved this topic to the "adding features" board.

Please note that Audacity does not record as a normal audio file. Audacity works with "projects" that comprise of a "project file" (.AUP file extension) plus lots of small audio data files (.AU file extension). To create a normal audio file from an Audacity project, you must "export" the audio to an audio file.
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Re: First-In-First-Out' (FIFO), fix length recording

Permanent link to this post Posted by steve » Tue Mar 07, 2017 10:20 am

goesproto.call wrote:or there are work arounds to achieve the same effect.


If your computer supports running two recording applications at the same time (any recording application) then you may be able to automate recording and saving using an automation scripting application such as Autohotkeys. You could then run one recorder for an hour, then just before the hour is up, start the second recorder, then stop the first recorder and save the file. Then just before 2 hours is up, delete the first file and start recording again with the first recorder.

I'd guess a likely problem with this approach would be data congestion interrupting the recording while the previous recording is being saved.
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Re: First-In-First-Out' (FIFO), fix length recording

Permanent link to this post Posted by goesproto.call » Mon Mar 13, 2017 5:35 am

kozikowski wrote:That would be the "surveillance mode" that Audacity doesn't have. It won't on-the-fly time stamp, either.

You would think there's no down side to those features, but you haven't had to deal with people trying to use Audacity for legal actions and law enforcement.

Koz


Yeah but there's always workarounds to these kind of things, just not as elegant and efficient. So if that is the main reason the feature is not implemented, I'd say that's kind of silly.

steve wrote:
goesproto.call wrote:Please let me know if this feature already exist and I overlooked it,

No, this feature is not available in Audacity, so I've moved this topic to the "adding features" board.

Please note that Audacity does not record as a normal audio file. Audacity works with "projects" that comprise of a "project file" (.AUP file extension) plus lots of small audio data files (.AU file extension). To create a normal audio file from an Audacity project, you must "export" the audio to an audio file.


I do have an idea of how that works, and think that due to that nature, it would be easier to implement that feature.

The little .au files that are around 1MB each, are fragments of the entire audio in the project. I believe audacity keeps an index of all the little files and put them together when called for (when exporting). So, if the index can be made such that the older files gets deleted (and the index updated) when the project folder reaches its preset capacity, then the FIFO feature can be implemented with relative ease.

steve wrote:
goesproto.call wrote:or there are work arounds to achieve the same effect.


If your computer supports running two recording applications at the same time (any recording application) then you may be able to automate recording and saving using an automation scripting application such as Autohotkeys. You could then run one recorder for an hour, then just before the hour is up, start the second recorder, then stop the first recorder and save the file. Then just before 2 hours is up, delete the first file and start recording again with the first recorder.

I'd guess a likely problem with this approach would be data congestion interrupting the recording while the previous recording is being saved.


Thanks for the idea. I think audacity portable can run multiple instances simultaneously. Now to figure out how to trigger the recording, stopping and deleting via command lines.
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Re: First-In-First-Out' (FIFO), fix length recording

Permanent link to this post Posted by steve » Mon Mar 13, 2017 4:23 pm

goesproto.call wrote:Now to figure out how to trigger the recording, stopping and deleting via command lines.

Perhaps easier to use an application that is designed to be run from the command line?
(example: http://sox.sourceforge.net/)
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