/transcribe-audio

name: transcribe-audio
description: Transcribes video audio using WhisperX, preserving original timestamps. Creates JSON transcript with word-level timing. Use when you need to generate audio transcripts for videos.

Skill: Transcribe Audio (parent brief)

> **Note:** In the library pipeline, transcription runs mechanically via `ruby lib/buttercut/process_footage.rb transcripts <library>` (using `TranscribeJob`), not by dispatching this sub-agent — so footage analysis comes out identical across models. The WhisperX command lives in exactly one place, `lib/buttercut/transcribe_job.rb`, which also runs standalone: `ruby lib/buttercut/transcribe_job.rb <video_path> <output_dir> <language_code> <whisper_model>`. `refine_instructions.md` remains the playbook for the separate (judgment) refinement step that `analyze-video` Step 3 dispatches.

Transcribes video audio using WhisperX and produces a clean JSON transcript with word-level timing.

`SKILL.md` is the parent's dispatch brief. The sub-agent's working prompt lives in `agent_prompt.md` — inline its contents when launching the Task agent. Don't pass `SKILL.md`.

Parallelism

Launch at most **2 in parallel**. WhisperX is already multithreaded internally (~4 CPU threads via CTranslate2); 2 processes is the throughput-vs-RAM sweet spot on a 16GB machine.

Inputs to gather and pass inline

The parent reads `library.yaml` and `settings.yaml` and passes these values inline in each agent's prompt:

• `video_path` — absolute path to the video file
• `transcript_output_dir` — where to write the transcript JSON (e.g. `libraries/<library>/transcripts`)
• `language_code` — ISO 639-1 code (e.g. `en`, `es`) — parent maps from library.yaml's `language` name
• `whisper_model` — model size from settings.yaml (e.g. `small`, `medium`, `turbo`)
• `transcript_refinement` — boolean from library.yaml. If `true`, also pass:
• `user_context` (may be empty string)
• `footage_summary` (may be empty string)

After the agent returns, update `library.yaml` with `transcript: <filename>.json`.

Next step

Once all videos have audio transcripts, dispatch `analyze-video` for visual descriptions.

Dependencies

WhisperX must be installed. Use the **setup** skill to verify.