External Record Start/Stop Control

It would be very useful to me to be able to start and stop the record process, and maybe to pause it too, with an external electrical signal such as a serial or parallel port bit. There are many applications to which Audacity could be put if it could be controlled this way.

Although it would be feasible to emulate the keyboard and use the “R” and “S” keystrokes to start and stop recording, this seems excessively complex. I’m not aware of any off-the-shelf device which could be purchased to inject these keystrokes into the keyboard input or via a USB input using a USB keyboard driver, so using the keyboard commands probably would require building hardware.

How about a wireless keyboard?

Such as? What do you have in mind?

Bluetooth keyboards.

Simulating keypresses is not straightforward and Audacity does not work well over a network – although Remote Desktop programs could be tried. Audacity hates sending hot audio data over a network.

A keypress is two commands: Press and Release. That’s how the computer knows whether or not to go into TypeMatic®. It’s not just a contact closure. And if you do use a contact closure, you have to debounce and clean it up.

Radio Shack has been selling microcontrollers and you might be able to work something up with that.



Thanks for your reply. But the topic is “Adding Features to Audacity”. There are all sorts of external complex hardware solutions that would become projects in themselves and require replicating the hardware for anyone else to use them. I raised the question here on the hope that it would be considered as a software enhancement that would be usable by others.

Yes, I know how PC and AT keyboards work. It’s actually not that difficult to emulate the data stream with a few SSI ICs and probably less work than getting involved in a firmware development project.

A serial port controller is not software. For Audacity to support control via serial port data it would need to know the protocol and encoding used by the “device” that is sending the data. I don’t see how Audacity could provide software support for an unknown/arbitrary control device over an arbitrary/unknown interface port. Perhaps it would be clearer what you mean if you gave an example.

Not so. I said serial or parallel port bit, meaning a status bit. I should have been more explicit. There is no protocol involved in a polled status bit. it has either of 2 states: on or off, depending on the electrical condition imposed on the connector pin.