A USB sound device plugged into the RockRecorder server can record analog audio: a radio's speaker or line out, a scanner, or a console's logging output. Each input on the device is a channel, and it records whenever there's sound.
You need to be a SuperAdmin, and the server needs the USB Audio license.
1. Plug in the device
Plug the USB sound device into the server and connect your audio to its inputs. Keep it in the same USB port from now on: RockRecorder remembers the device by its port, so two identical devices can't swap places after a restart.
On a virtual machine, pass the USB device through to the VM first.
2. Add the interface
- Open the user menu (top right) and go to Administration > Recording > Recording Interfaces.
- Click Add recording interface.
- Choose Recorder Type: USB Audio, and pick the device under USB audio device. Each one is listed with its number of inputs and USB port, for example (2 inputs, USB port 2).
- Give it a name and click Create Recording Interface.
No device listed? It isn't plugged in, or it has no inputs. Plug it in and reload the page.
3. Add a channel for each input
On the Channels tab, give each channel a name and choose its Input (Input 1, Input 2…), then click Add. Use Gain to make a quiet source louder (+6 dB is about double).
For many inputs, use CSV > Import from CSV… with the columns channel,input,gain_db,enabled, for example Fire base radio,2,0,1.
Then click Apply at the top of the interface page.
4. Set the voice activation
A sound card sends audio all the time, so each channel records only when there's sound. On the Settings tab, under Voice activation (VOX):
| Setting | What it does | Default |
|---|---|---|
| Start recording above | How loud it must get to start a recording (-60 to -20 dB). Lower picks up quieter sound; raise it if background noise starts recordings | -45 dB |
| Stop after this much quiet | Pauses shorter than this stay in one recording (1 to 10 seconds) | 2 seconds |
Each recording also keeps a moment of audio from just before the sound started, so the first word isn't cut off.
5. Check it's working
Talk on the radio, or play audio into the input. A recording appears on the Recordings page a couple of seconds after the sound stops. USB audio has no talker information, so the Alias and UID columns stay blank.
| Problem | What to do |
|---|---|
| Nothing records | Lower Start recording above, or raise the channel's Gain |
| It records all the time, or records noise | Raise Start recording above, or lower the gain |
| The device shows Not plugged in | It was unplugged or moved to another USB port. Plug it back into the same port, or pick it again on the Settings tab and click Apply |
If you unplug the device, recordings so far are saved, and recording starts again within 5 seconds of plugging it back in. The recorder's log is /opt/rockrecorder/logs/usb.log.