Multi-Format Book Extractor

Extract chapters from PDF, MOBI, and AZW3 files into individual numbered markdown files. Mirrors the epub-chapter-extractor pattern for non-EPUB formats.

Dependencies

• PDF: pymupdf — auto-installed via --with pymupdf
• Scanned PDF OCR fallback: requests (--with requests) + a Gemini key in $GEMINI_API_KEY / $GOOGLE_API_KEY (read from cornelius/.env if unset)
• MOBI / AZW3: calibre must be installed

  brew install --cask calibre

Single Book

cd $PROJECT_ROOT/.claude/skills/multi-format-book-extractor && \
uv run --with pymupdf --with requests python extract_book.py "/path/to/book.pdf" [output_dir]

If output_dir is omitted, creates a folder named after the file in the same directory.

Scanned / Image-Only PDFs (auto-OCR)

Some PDFs are pure page scans with no text layer — pymupdf extracts nothing and would silently write empty files. extract_book.py now samples the text layer first (_has_text_layer) and, when a PDF looks image-only, automatically routes it to Gemini 2.5 Flash OCR (ocr_pdf.py).

• Renders each page to PNG (~180 DPI), batches pages per API call, transcribes verbatim to Markdown (preserves verse line breaks, Sanskrit/Tibetan diacritics, footnotes), and writes NN_pages-S-E.md chunk files.
• Resumable: re-running skips chunk files already written (≥200 chars), so an interrupted long book picks up where it left off.
• Cost is ~$0.002/page on Flash (a 300-page book ≈ $0.60).

Run OCR directly (e.g. to tune params or force it):

cd $PROJECT_ROOT/.claude/skills/multi-format-book-extractor && \
uv run --with pymupdf --with requests python ocr_pdf.py "/path/to/scan.pdf" [output_dir] \
  [--model gemini-2.5-flash] [--dpi 180] [--pages-per-call 5] [--pages-per-file 20] [--concurrency 6]

Batch Extraction (Parallel)

Extract all PDFs, MOBIs, and AZW3s from a directory in parallel:

SKILL="$PROJECT_ROOT/.claude/skills/multi-format-book-extractor"
UVX="uv"
DIR="/path/to/books"

for book in "$DIR"/*.{pdf,mobi,azw3}; do
  [ -f "$book" ] || continue
  stem="${book%.*}"
  [ -d "$stem" ] && echo "Skipping: $(basename "$book") (already extracted)" && continue
  echo "Starting: $(basename "$book")"
  (cd "$SKILL" && $UVX run --with pymupdf --with requests python extract_book.py "$book") &
done
wait
echo "All done"

Output Format

Each book gets a subfolder named after the file (without extension):

book-name/
├── 01_introduction.md
├── 02_chapter-one.md
└── ...

• PDF with TOC: one file per chapter (uses level-1 TOC; falls through to level-2 if < 5 top-level entries, e.g. books structured as Parts)
• PDF without TOC: 20-page chunks (01_pages-1-20.md, etc.)
• Scanned / image-only PDF: auto-routed to Gemini OCR → 20-page chunks (01_pages-1-20.md) with <!-- page N --> markers
• MOBI / AZW3: same output quality as epub-chapter-extractor (converts via calibre first)

After Extraction

open /path/to/books/