Transcribe Audio

Transcribe audio files to text using whisper-cpp locally on your Mac.

Your Task

Given an audio file path as argument:

1. Resolve the file path — expand ~ and verify the file exists
2. Convert to WAV if needed — if the file is not .wav, convert it using ffmpeg:

   ffmpeg -i <input> -ar 16000 -ac 1 /tmp/whisper_transcribe_tmp.wav
   

3. Run whisper-cli to transcribe:

   whisper-cli -m /opt/homebrew/share/whisper-cpp/ggml-medium.bin -l <lang> -np <wav_file>
   

   • Default language: fr (French)
   • If the user specifies a language (e.g., /transcribe file.opus en), use that instead
   • The -np flag suppresses debug output, showing only transcription results
4. Output the clean transcription — present only the transcribed text to the user, stripping timestamps
5. Clean up — if a temp WAV was created, delete /tmp/whisper_transcribe_tmp.wav

Guidelines

DO:

• Always check the file exists before processing
• Convert non-WAV files (opus, mp3, ogg, m4a, flac, etc.) to WAV first
• Use -ar 16000 -ac 1 for WAV conversion (16kHz mono, optimal for Whisper)
• Strip timestamps from output to give clean text
• Redirect ffmpeg and whisper stderr to /dev/null for clean output

DON’T:

• Don’t try to pass non-WAV files directly to whisper-cli (it only reads WAV)
• Don’t leave temp files behind after transcription
• Don’t include whisper debug/timing output in the result

Input Handling

• Single argument: audio file path (e.g., /transcribe ~/Downloads/audio.opus)
• With language: file path + language code (e.g., /transcribe ~/Downloads/audio.opus en)
• No argument: ask the user for the file path

Tools Used

• Bash: for running ffmpeg (conversion) and whisper-cli (transcription)

Dependencies

• whisper-cpp (installed via Homebrew, provides whisper-cli)
• ffmpeg (installed via Homebrew, for audio format conversion)
• Model file: /opt/homebrew/share/whisper-cpp/ggml-medium.bin

Example Usage

/transcribe ~/Downloads/voice-message.opus
/transcribe ~/Downloads/meeting.mp3 en
/transcribe ~/Desktop/recording.wav