Install

First, install blackhole-2ch, which is necessary for capturing sound from other application.

You may follow the official guide or just use the below command.

brew install blackhole-2ch

Second, create a multi-output device in Audio MIDI Setup, which could be accessed through Lauchpad or by searching midi in Spotlight (⌘+space). This device should use both your favour speakers and Blackhole 2ch.

Please ensure that your favour spearkers are listed above Blackhole 2ch in the device list.

Third, set up whisper.cpp by the below command.

git clone https://github.com/ggerganov/whisper.cpp ~/Desktop/whisper.cpp
cd whisper.cpp

bash models/download-ggml-model.sh base.en # download basic model
make stream

# start speech recogntion
./stream -c 0

In the last command, the number 0 is the device ID of BlackHole, which may vary depending on the specific device. If you are unsure of the device ID, you can run ./stream and check the first lines of the output.

init: found 5 capture devices:
init:    - Capture device #0: 'BlackHole 2ch'
init:    - Capture device #1: 'External Microphone'
...

You may check other command options by

./stream -h

There are other model avaialable as well.

Model	Disk	Mem	WER(%)
tiny	75 MB	~125 MB	6
base	142 MB	~210 MB	4.9
small	466 MB	~600 MB	4
medium	1.5 GB	~1.7 GB	4.1
large	2.9 GB	~3.3 GB	4

Usage

If you want to use live caption for an application such as Zoom, you will need to select the multi-output device as the speaker for that application.