Audiobook

Use this skill when Kip asks to "make an audiobook of...", "narrate this article", "read this aloud", or supplies a URL/PDF/EPUB and wants a long-form audio file back. Default output is a single MP3 in ~/audiobooks/ with embedded ID3 tags and (when supported by the container) chapter markers per section.

Command

{{HOME}}/bin/article-audiobook-render.sh <url> [flags]

Direct invocation (equivalent):

python3 {{HOME}}/.openclaw/workspace/skills/audiobook/audiobook.py <url> [flags]

Flags

Test example

{{HOME}}/bin/article-audiobook-render.sh \
  https://www.vatican.va/content/leo-xiv/en/encyclicals/documents/20260515-magnifica-humanitas.html

Expected stdout (one line per phase, ending with a JSON summary):

fetch ok bytes=312841
extract ok title="Magnifica Humanitas" author="Pope Leo XIV" chars=158203
chunk ok sections=18 chunks=42 max_chars=3800
tts provider=openai voice=alloy chunks_total=42 cached=0 rendered=42
concat ok duration=05:12:47
tag ok format=mp3 path={{HOME}}/audiobooks/2026-05-30_magnifica-humanitas.mp3
{"title":"Magnifica Humanitas","author":"Pope Leo XIV","duration_seconds":18767,"runtime":"5h12m","path":"{{HOME}}/audiobooks/2026-05-30_magnifica-humanitas.mp3","chapters":18}

Reply to Kip with the human summary: Generated audiobook for "<title>" by <author>. Runtime: <h>h<m>m. File saved to <path>.

Caching

Per-chunk MP3 fragments are written to ~/.cache/openclaw-audiobook/<sha>.mp3 where <sha> = sha256(provider + voice + speed + chunk_text). Repeat runs of the same URL with the same voice/speed only re-render chunks whose source text actually changed. The cache is safe to delete at any time.

Providers

Default and fallback order live in config.yaml. Provider credentials come from ~/.openclaw/.env:

• OPENAI_API_KEY — openai
• ELEVENLABS_API_KEY — elevenlabs
• PIPER_BIN (path), PIPER_VOICE (model path) — piper (offline)
• KOKORO_BIN, KOKORO_VOICE — kokoro (offline)

If the requested provider is unavailable, the script falls back to the next provider in provider.fallbacks. Piper is the recommended offline fallback on the Pi (CPU only, ~1×realtime on a Pi 4).

Piper (offline, installed on kip)

• Binary: {{HOME}}/.local/bin/piper (Python package piper-tts v1.4.2)
• Models live in {{HOME}}/.local/share/piper/ — one .onnx + matching .onnx.json
• Default voice (from ~/.openclaw/.env → PIPER_VOICE): en_US-amy-medium.onnx
• Currently installed voices on kip:
  • en_US-amy-medium.onnx — warm female, default
  • en_US-hfc_male-medium.onnx — Home Assistant Cloud male, neutral news read
  • en_US-ryan-high.onnx — clear male, highest quality (~2-3× slower on Pi)
• Swap voices for a single run by exporting PIPER_VOICE inline:

  PIPER_VOICE={{HOME}}/.local/share/piper/en_US-hfc_male-medium.onnx \
    ~/bin/article-audiobook-render.sh --provider piper <url>
  

• More voices: download <name>.onnx + <name>.onnx.json from https://huggingface.co/rhasspy/piper-voices into ~/.local/share/piper/. Browse en/en_US/<voice>/<quality>/ (qualities: low, medium, high).
• Cache keying respects the resolved voice file path, so swapping PIPER_VOICE triggers a fresh render rather than returning a stale fragment.

Source types

Logs

Per-run JSONL log at ~/audiobooks/_log.jsonl. Failed runs include the phase that failed (fetch|extract|chunk|tts|concat|tag) plus the exception summary.

Errors and retries

• Network fetch: 3 retries with exponential backoff (handled by httpx)
• TTS request: 2 retries per chunk, then fall through to the next provider in the fallback chain for that chunk only (mixed-provider runs are allowed and logged)
• ffmpeg concat: fails fast — broken cache fragments are deleted and the run retries once

RSS feed (nice-to-have)

If rss.enabled: true in config.yaml, every completed audiobook is appended to ~/audiobooks/feed.xml (Atom/Podcast-compatible). The feed is served by the nginx tailnet vhost if ~/audiobooks/ is symlinked under the files site.

When NOT to use this skill

• Short text (< 500 chars) — just narrate inline if needed.
• Paywalled or login-required URLs — extraction will fail; tell Kip.
• Copyrighted commercial books — out of scope; refuse.