Speech To Text

Speech to Text

Transcribe audio files locally using OpenAI Whisper — no API key required.

Prerequisites

Install local Whisper:

pip install openai-whisper
# Requires Python 3.8+

Also install ffmpeg (required by Whisper for audio processing):

brew install ffmpeg

First run downloads the model automatically to ~/.cache/whisper/.

Model sizes (speed vs accuracy tradeoff): | Model | Size | Speed | Accuracy | |-------|------|-------|----------| | tiny | 39MB | Very fast | Basic | | base | 74MB | Fast | Good | | small | 244MB | Moderate | Better | | medium | 769MB | Slow | High | | large | 1.5GB | Very slow | Best |

Default recommendation: base for speed, small for quality.

Commands

Basic Transcription

whisper audio.mp3                          # Auto-detect language, base model
whisper audio.mp3 --model small            # Better accuracy
whisper audio.mp3 --language en            # Force English
whisper audio.mp3 --language zh            # Force Chinese
whisper audio.mp3 --language ja            # Force Japanese

Output Formats

whisper audio.mp3 --output_format txt      # Plain text
whisper audio.mp3 --output_format srt      # Subtitles with timestamps
whisper audio.mp3 --output_format vtt      # WebVTT subtitles
whisper audio.mp3 --output_format json     # Full JSON with timestamps
whisper audio.mp3 --output_format all      # All formats at once

Output Directory

whisper audio.mp3 --output_dir ~/transcripts/

Transcribe from Video

whisper meeting.mp4 --model small --output_format txt

Batch Transcription

whisper *.mp3 --model base --output_dir ./transcripts/

Usage Examples

"Transcribe meeting.m4a"

whisper meeting.m4a --model small --output_format txt --output_dir ./
cat meeting.txt

"Transcribe in Chinese"

whisper recording.mp3 --language zh --model small

"Generate subtitles for video.mp4"

whisper video.mp4 --model medium --output_format srt --output_dir ./

"Quick transcription (fast)"

whisper audio.mp3 --model tiny

OpenAI API Alternative

If local Whisper is too slow and you have an API key:

# Set key: export OPENAI_API_KEY=sk-...
curl https://api.openai.com/v1/audio/transcriptions \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -F file="@audio.mp3" \
  -F model="whisper-1"

Rules

• Check if whisper is installed: which whisper || python3 -m whisper --help 2>/dev/null
• If not installed, show pip install openai-whisper and stop
• Check if ffmpeg is also installed: which ffmpeg
• Default to base model for files under 30 minutes, small for longer
• Warn user if using medium or large — processing may take several minutes
• Supported input formats: mp3, mp4, m4a, wav, ogg, flac, webm, mov
• Output transcript file path in the response
• For very long files (>1 hour), suggest splitting with ffmpeg first
• Never display raw JSON output — summarize and show the transcript text

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: claude-world
• Source: claude-world/claude-agent
• License: MIT

Install and usage instructions live in the source repository linked above.