feat: Transcribe output from audio devices to keyboard or a file

[richiejp]

• Allow setting capture device
• Allow outputting transcriptions to a file

These changes allow you to transcribe the audio you are listening to rather than the microphone.

I find this especially useful for transcribing and translating meetings without having to rely on the meeting software having these features built in.

The transcription can be written to a file and you can use any software to read that file. Also I'm considering doing something in LocalAI so you can view a log of transcriptions there or do some further processing on them.

From the new README:

Example Workflow: Transcribing an Online Meeting or Video Stream

To create a transcript of an online meeting or video stream by capturing system audio:

1. List available capture devices:

   ./voxinput devices

   Identify the monitor device, e.g., "Monitor of Built-in Audio Analog Stereo".

2. Start the daemon specifying the device and output file:

   VOXINPUT_CAPTURE_DEVICE="Monitor of Built-in Audio Analog Stereo" ./voxinput listen --output-file meeting_transcript.txt

   Note: Add --no-realtime if you prefer the HTTP API.

3. Start recording:

   ./voxinput record

4. Play your online meeting or video stream; the system audio will be captured.

5. Stop recording:

   ./voxinput stop

6. The transcript is now in meeting_transcript.txt.