Rendering and cost

Stage ③ Render synthesises the audio.

Passages

The book is cut at scene and paragraph boundaries into passages of a couple of thousand characters.

The size is chosen for quality, not for a technical limit. Engines will accept far longer input than this, but their own documentation warns that delivery degrades over a long single generation — so passages are kept to the length that reads well.

Only what changed is re-rendered

Every passage is content-hashed. The hash covers the text, its direction, the engine, the voice and the pronunciation list — everything that affects how it sounds.

When you render, the studio compares hashes and renders only what is stale.

Position is deliberately not part of the hash. So inserting a paragraph in chapter 2 does not invalidate chapters 3 to 40: those passages moved, but they did not change, and they stay cached.

That is the whole feature. It is what makes it reasonable to narrate a book you are still editing.

What it costs

A flat base charge from 15 credits, scaled by the length of what you are actually rendering.

The quote and the charge come from the same calculation, so the number on the button is the number you pay.

Because only stale passages are rendered, a re-render after a light edit costs a fraction of the first pass.

It runs in the background

Rendering is a worker job. Close the tab; it keeps going. The bookshelf shows the job's state — queued, running, failed or done — so a job that went wrong never looks like a book you simply never narrated.

Cancelling, and refunds

Stop works at any point.

• A job no worker has started ends immediately and costs nothing.
• A running job stops at a passage boundary. You are refunded for the passages that had not been rendered.

Rendered passages stay cached and are free to reuse, which is why the refund is partial: a full refund would let anyone narrate ninety per cent of a book, cancel, keep the audio, and re-run for the last ten.

A failure is different, and refunds in full. A crash is our fault; a cancel is your choice.

What to watch for

• One narration job at a time per account.
• Changing the engine or voice makes every passage stale, and every passage is charged again. Audition first, decide once.
• Render late. Not because rendering is destructive, but because tagging and editing after a render both cost a re-render of what they touch.
• The included narrator is dramatically cheaper. If budget matters more than performance, that is the decision that moves the number, not the length of the book.