Seedance 2.5 image-to-video: first-frame-driven shot extension

Use a single product still frame as the first frame, and extend it into a continuous shot with synchronized audio using Seedance 2.5's image-to-video capability. The piece highlights three controllable points: the first frame constrains the starting point and aspect ratio of the image (aspect_ratio is adaptive, and the output follows the first frame's ratio), duration determines the clip length (8 seconds in this case), and generate_audio provides ambient sound and detail sounds within the same generation. The prompt is only responsible for camera movement, lighting ratio changes, and sound description, without repeatedly describing the subject's appearance, making it easy to observe the model's motion inference and stability given the starting image. Applicable scenarios: dynamic freeze-frame extension for product ads, e-commerce hero image to short video, rapid validation from storyboard first frame to final cut, and front-end testing for serialized short videos that require consistent character or product appearance. For the stability of complex action physics and multi-subject interaction, it is still recommended to validate with live-action or segmented generation.