TikTok Symphony with Seedance 2.5: 30-second AI video ads

TikTok's August 3 2026 post says Symphony, integrated with Dreamina Seedance 2.5, "now supports up to 30 seconds of video generation, up from a 15 second maximum before". It is rolling out to select advertisers in select markets. Outside that rollout, Sume's video API accepts seedance-2.5 at 4 to 30 seconds.

TikTok's details are from its Symphony announcement, read 2026-09-30. Sume's from the video generation docs.

Where is Symphony's 30-second option available?

Per TikTok, in the creation flow across Symphony Creative Studio and Symphony Automations in TikTok Ads Manager, for select paid advertisers in select markets. If your account is not in that group, you cannot use it there yet.

What does seedance-2.5 accept on Sume?

The docs state that seedance-2.5 accepts 4–30 seconds at 480p, 720p and 1080p, and that every other catalog model tops out at 15 seconds. The models endpoint lists accepted supported_input_references types per model, such as image_url, video_url and audio_url, and 9:16 is a valid aspect_ratio for vertical ads.

How do I request a 30-second vertical clip?

Send model: "seedance-2.5", duration: 30 and aspect_ratio: "9:16" to the video endpoint, after checking the model's entry on the models endpoint. Reference-count limits are covered in Seedance 2.5 reference limits.

What if I need more than 30 seconds?

Join clips on a timeline; the steps are in 1-minute AI video generator.