AI video audio by model: toggle, always on, or none on Sume

On Sume, audio depends on the model row. Seedance 2.5, the Seedance 2.0 rows, Wan 3.0 and Kling 3 generate audio when generate_audio is on; MiniMax H3, MiniMax H3 Max and Gemini Omni Flash 1.1 always produce audio and reject or ignore the switch; Grok Imagine Video 1.5 and Genjutsu produce none. Decide this before you choose a model, because it changes both the price and your edit.

Audio behaviour per row

The catalog constraints say it directly. For the always-on rows, omit the field; Gemini Omni Flash rejects generate_audio: false outright.

Why it matters for editing

If you plan to lay a music bed or a voice-over, an always-on row hands you a clip with its own sound that you then have to detach or duck. A toggle row lets you generate silent and mix cleanly. If you want synced ambient sound or speech from the model, choose a row that makes it by default and check the transcript with a video inspect step before you ship.

Cost

Kling 3 is the one row with two published per-second prices, one with audio and one without. For the others, audio is part of the model's price. Read the pricing fields in GET /v1/video-router/models for the current figures.