---
id: T04
parent: S01
milestone: M001
provides: []
requires: []
affects: []
key_files: ["whisper/transcribe.py", "whisper/requirements.txt", "whisper/README.md"]
key_decisions: ["Whisper import deferred inside transcribe_audio() so --help and ffmpeg validation work without openai-whisper installed", "Audio extracted to 16kHz mono WAV via ffmpeg subprocess matching Whisper expected format", "Creator folder inferred from parent directory name by default, overridable with --creator"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "1. python3 whisper/transcribe.py --help — exits 0, shows full usage with all CLI args and examples. 2. python3 whisper/transcribe.py --input /tmp/fake.mp4 --output-dir /tmp/out — exits 1 with clear ffmpeg-not-found error, confirming validation works. 3. Python AST parse confirms syntax validity."
completed_at: 2026-03-29T21:57:39.524Z
blocker_discovered: false
---

# T04: Created desktop Whisper transcription script with single-file/batch modes, resumability, spec-compliant JSON output, and ffmpeg validation

> Created desktop Whisper transcription script with single-file/batch modes, resumability, spec-compliant JSON output, and ffmpeg validation

## What Happened
---
id: T04
parent: S01
milestone: M001
key_files:
  - whisper/transcribe.py
  - whisper/requirements.txt
  - whisper/README.md
key_decisions:
  - Whisper import deferred inside transcribe_audio() so --help and ffmpeg validation work without openai-whisper installed
  - Audio extracted to 16kHz mono WAV via ffmpeg subprocess matching Whisper expected format
  - Creator folder inferred from parent directory name by default, overridable with --creator
duration: ""
verification_result: passed
completed_at: 2026-03-29T21:57:39.525Z
blocker_discovered: false
---

# T04: Created desktop Whisper transcription script with single-file/batch modes, resumability, spec-compliant JSON output, and ffmpeg validation

**Created desktop Whisper transcription script with single-file/batch modes, resumability, spec-compliant JSON output, and ffmpeg validation**

## What Happened

Built whisper/transcribe.py implementing all task plan requirements: argparse CLI with --input, --output-dir, --model (default large-v3), --device (default cuda); ffmpeg audio extraction to 16kHz mono WAV; Whisper transcription with word-level timestamps; JSON output matching the Chrysopedia spec format (source_file, creator_folder, duration_seconds, segments with words); resumability via output-exists check; batch mode with progress logging. Deferred whisper import so --help works without the dependency. Created requirements.txt and comprehensive README.md.

## Verification

1. python3 whisper/transcribe.py --help — exits 0, shows full usage with all CLI args and examples. 2. python3 whisper/transcribe.py --input /tmp/fake.mp4 --output-dir /tmp/out — exits 1 with clear ffmpeg-not-found error, confirming validation works. 3. Python AST parse confirms syntax validity.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `python3 whisper/transcribe.py --help` | 0 | ✅ pass | 200ms |
| 2 | `python3 whisper/transcribe.py --input /tmp/fake.mp4 --output-dir /tmp/out` | 1 | ✅ pass (expected ffmpeg error) | 200ms |
| 3 | `python3 -c "import ast; ast.parse(open('whisper/transcribe.py').read())"` | 0 | ✅ pass | 100ms |


## Deviations

Added --creator CLI flag for overriding inferred creator folder name. ffmpeg-python included in requirements.txt per plan but script uses subprocess directly for reliability.

## Known Issues

None.

## Files Created/Modified

- `whisper/transcribe.py`
- `whisper/requirements.txt`
- `whisper/README.md`


## Deviations
Added --creator CLI flag for overriding inferred creator folder name. ffmpeg-python included in requirements.txt per plan but script uses subprocess directly for reliability.

## Known Issues
None.
