Seedance API Review For Trailer Still To Motion

Trailer editors still burn an afternoon when a face drifts between shot two and shot three. The poster still is already approved. The motion pass is not. A gateway such as APIPod only helps that handoff if the route you call can take the still and can refuse a resolution the contract does not offer.

APIPod puts the image-to-video contract on public model pages, and those pages are the review. Fast and Standard are separate calls with separate resolution lists. A trailer desk that treats them as two adjectives for one button will ask for a frame size the Fast route cannot accept.

Lock The Trailer Brief Before Any Motion

Start from the still the poster already signed off, not from a fresh description of the actor. The image-to-video call requires three fields: the model id, a prompt, and image_urls. If image_urls is missing, the call never moves that poster, and you have started a different job. Put the approved still in that array and write the prompt as camera and action, because the still is already carrying the face.

The prompt field allows up to 30,000 characters, and the model page asks you to stay near 1,000 English words. Past that, the note on the schema is blunt: long text scatters, and the model keeps the key points while dropping the rest. A trailer brief that pastes the whole scene description, the music cue, the legal line, and three alternate endings will lose the one instruction that mattered, which is usually the eyeline or the direction of the push-in. Write the shot. Leave the rest in the edit.

Read The Fast Contract Before You Ask For 4K

The Seedance API groups Standard, Fast, and Mini as editions. For a poster that must move, the image-to-video ids are the ones to read. Fast is seedance-2.0-fast-i2v. Standard is seedance-2.0-i2v. Both default to 720p. Only one of them can be asked for 1080p or 4k.

Fast Stays Inside 720p On This Route

On the Fast image-to-video schema the resolution enum is 480p and 720p. The default is 720p. There is no 1080p value and no 4k value. A request that sends 4k to this model id is outside the contract, not a quality setting the route will quietly upgrade. That is the useful failure. You find out before a render queue, because the allowed list is on the page.

480p is the other legal value, and it is the wrong one for a trailer still you already like. The poster was approved at a size where the eyes read. Dropping the motion pass to 480p to save time makes the face softer than the still the director signed. If the temp is only a timing test, 720p is already the default. Leave it there.

Standard Can Request 1080p Or 4K

The Standard image-to-video schema lists 480p, 720p, 1080p, and 4k, and it still defaults to 720p. You do not get 4k by forgetting the field. You get 720p, same as Fast, until you set 1080p or 4k on purpose. That default is the right first look at motion. It is the wrong delivery file if the brief says the teaser must match a 4K master.

Use Fast when the question is whether the still can move without the face sliding. Move the same image_urls and a tightened prompt to seedance-2.0-i2v when the cut is locked and the delivery spec names 1080p or 4k. Do not send the 4k value to the Fast id and then wonder why the call was rejected. The enum already answered.

Match The Cut To A Duration The Route Allows

Both image-to-video routes take duration as an integer from 4 through 15. The default is 5. There is no 3-second value and no 20-second value on these schemas. A trailer beat that was timed at 8 seconds in the edit needs duration 8. Leaving the field empty does not inherit the edit. It inherits 5.

Five Seconds Is The Default Teaser Beat

Five seconds is long enough for a push-in on a poster face and short enough to throw away. That is the check for the first pass: one camera move, one action, the still held in image_urls. If the eyes drift or the costume edge crawls, you have spent a 5-second call, not a 15-second one. Change the prompt and send again. Do not lengthen a shot that already failed the face.

A temp that looks calm at 5 seconds can still fail when the move has to finish. The schema will not warn you about that. You have to play the 5-second result against the still, then decide whether the same prompt deserves 8 or 10. The duration list is a menu of legal lengths, not a promise that every length holds the likeness.

Fifteen Seconds Is The Long End Of One Call

Fifteen is the maximum on both of these image-to-video routes. A trailer that needs a 40-second arc is several calls, or a later edit that joins them. One request will not cover the whole teaser. Plan the beats as separate durations that each sit between 4 and 15, and keep the same still in image_urls so the face has one source.

Jumping straight to 15 because the field allows it is how a bad prompt gets expensive in time. You wait out the long version, then you see the same drift you would have seen at 5 seconds. Lock the move at the default. Extend only after the short pass holds.

Keep One Face Across The Two Motion Passes

The comparison that matters on a trailer desk asks whether the Fast pass and the Standard pass are the same shot at two resolutions, rather than lining up every edition in the catalog. Hold the still, the prompt, and the duration fixed. Change the model id, and change resolution only when you move to Standard.

Read the table as a gate, not as a ranking. If the delivery is a 720p temp for an internal trailer meeting, Fast is enough and Standard’s extra sizes are idle. If the delivery is a 4k tease for a public cut, Fast cannot place that order. APIPod will not invent a 4k enum on the Fast page because the poster is important.

Put the approved still beside the motion result before anyone else sees it. Drift in the jaw, a logo that crawls, a costume edge that melts: those are rejects, even when the camera move is pretty. The short pass exists so that reject happens on a 5-second 720p call. A wrong face at 4k is the same wrong face, larger.

Leave Synced Audio On Unless The Mix Says No

generate_audio defaults to true on the image-to-video schema. The field controls whether the clip contains audio synchronized with the picture. A trailer temp that arrives with its own bed will surprise a picture editor who expected a silent plate. If the mix is already cut, set the field to false before you send. If you leave it, you get sound.

That default is easy to miss because the required fields are only model, prompt, and image_urls. Audio is optional in the schema and on by default. Check it the way you check duration, because an empty field still carries that default.

APIPod’s job in this review is the contract, not a taste score. The pages say what Fast will accept and what only Standard will accept. They do not promise that a specific actor’s face will survive a fast push-in. That check is still the editor, still against the poster.

What A Trailer Desk Should Keep

Use the Fast image-to-video id when the still must move at 720p and the question is likeness. Skip it when the brief names 1080p or 4k, and send that order to the Standard id with the resolution set on purpose. Both routes default to 5 seconds and 720p, so an untouched request is a short 720p pass either way.

Keep image_urls pointed at the approved still, keep the prompt near the shot rather than the whole treatment, and do not ask Fast for a frame size that is not in its enum. APIPod is a fit for a trailer desk that will read those two model pages before it renders. It is a poor fit if the team wants one button that upgrades resolution on its own.

The face still has to match the poster when the clip comes back. The contract can stop an illegal 4k request. It cannot approve the performance.