Both generate video and synchronised audio in one pass. Seedance 2.5 pushes clip length to 30 seconds with heavy reference control; Veo 3.1 is Google's flagship with the smoothest cinematic look and easy access through Gemini and Flow.
Seedance 2.5 wins on clip length, reference inputs, and multi-character scenes. Veo 3.1 wins on out-of-the-box cinematic polish and availability in the Google ecosystem.
Pick Seedance 2.5 if you build longer scenes with specific characters, products, or camera angles and want up to 30 reference images steering the result.
Pick Veo 3.1 if you want the most dependable cinematic quality with the least setup, straight from Gemini or Flow.
Up to 30 seconds in one pass, with audio, and clips can be extended further. Most rivals, including Veo 3.1, top out around 8-10 seconds per generation.
It is live on ByteDance's Jimeng AI and Doubao apps, with API access via BytePlus ModelArk rolling out. Veo 3.1 is easier to reach internationally through Gemini and Flow.
Both generate synchronised audio natively. Veo 3.1 tends to produce cleaner dialogue; Seedance 2.5 lets you feed reference audio files for tighter control.