An image supplied to a video generator can serve two different purposes: specifying an opening or closing frame, or guiding the appearance of the scene. OpenRouter'scomparison exposes these as separate request options. A product shot intended to open the clip needs frame control; reference material can guide a character's appearance without fixing its position in the sequence. Models differ in which frame roles they accept, so choosing by price alone can leave a workflow unable to express its required ending.
