SK-404

Doc no. SK-404Rev 2026.09Sheet 2.1 of 4

U1

Kokoro Audiobook Studio

Turns textbooks and technical PDFs into chaptered .m4b audiobooks — entirely on-device, on the Apple Silicon GPU.

Source on GitHub $ audiobook-studio book.pdf -v bm_george

01

Block diagram

PDF.pdf / .epub Cleanbbox · hyphens Chaptersoutline · regex Kokoro-82MPyTorch · MPS FFmpeg mux.m4b + chapter marks GPU → Apple Books / VLC
Fig. 1 — PDF to audiobook signal path
02

Characteristics

Throughput~16× real-time — 55.5 h of audio from a 1,200-page textbook in ~3.5 h
ModelKokoro-82M on PyTorch MPS, one shared model across voices
PDF cleanupStrips running headers, footers and page numbers by position and repetition; de-hyphenates; reads two-column layouts in order
ChaptersPDF outline first, then heading patterns, then word-budget chunks
OutputReal, skippable chapter markers via FFMETADATA1 + FFmpeg AAC; also keeps a clean EPUB3
InterfaceOpenAI-compatible /v1/audio/speech server that starts on demand and shuts down on exit, plus a live terminal dashboard and --doctor
  • Python
  • PyTorch
  • PyMuPDF
  • FastAPI
  • FFmpeg
  • Rich
03

Measured performance

Apple Silicon M-series
TitlePagesAudioSynthesisSpeed
Astronomy 2e (OpenStax)1,200+55.5 h~3.5 h~16.0×
Additive Manufacturing Technologies5008.0 h~32 min~15.0×
Python Illustrated3209.0 h~38 min~14.2×