LTX 2.5 API

Introduction

LTX 2.5 Image to video animates an opening frame you supply for 5 to 20 whole seconds at 720p, 1080p, 2K or 4K. image_url and prompt are required; last_image_url adds an optional closing frame, and duration_seconds, resolution and seed behave as they do on Text to video. There is no aspect_ratio field: the opening frame fixes subject and composition and sets the output shape. Clips come back with a generated soundtrack and tasks run asynchronously. Upload only frames you are authorised to use; you are responsible for how the output is used.

Choose a LTX 2.5 mode by starting material

Key features

The opening frame is followed closely

Identity, wardrobe, set and light come from image_url, and that frame is followed closely. Because the image already carries the look, the prompt only has to carry what changes after it.

An optional frame for where the shot lands

last_image_url fixes the final composition and is valid only alongside image_url. It constrains the ending, not the route: the motion between the two frames is still generated, and across a long clip the middle can wander a long way. Two frames that disagree on light or wardrobe produce a visible negotiation between them, so prepare them as a continuous pair.

The same length, resolution and sound as the text endpoint

duration_seconds runs from 5 to 20 whole seconds, and longer clips wander further from a supplied closing frame. resolution offers 720p (default), 1080p, 2k (about 2560 px wide) and 4k. The output includes a generated audio track with no field to disable it, so plan to mute or replace it in the edit when you need your own mix.

Request parameters

Pricing

Prices are in credits, the same credits you use on the website (1 credit = $0.01). The hold is taken when the task is accepted and settled to the actual charge when it finishes; failed tasks are refunded.

Each task is rounded up to whole credits, so one run at the lowest tier costs 68 credits for a 5-second clip ($0.68).

For an exact number before you run, send the same body to POST /jobs/quote.

Use cases

A time-of-day transition between two approved frames

In the beach-to-bonfire example, image_url shows a couple on the beach at sunset and last_image_url shows the same two at night, wrapped in one blanket by a bonfire. The request runs 10 seconds at 1080p, and the prompt describes the passage rather than the destination: the sun going down and the firelight taking over. Pinning the ending lets the model invent the middle without drifting past a frame that is already approved.

Board-to-board shots for an edit

When a shot has to start on one storyboard frame and end on another, send both as image_url and last_image_url. The outgoing composition then matches the next cut, which is what makes a generated clip usable in a timeline instead of only as a standalone piece.

Motion added to a finished still

The candlelit-tub frame already holds the candles, the enamel and the wet emerald silk, so its prompt covers only the change: sinking into the water, hands dragged through soaked hair, eyes opening toward the camera. The deco-pool-backfall example is a physics beat instead, a backwards fall into water with rising bubbles and caustics crawling over the columns while the camera sinks along.

Prompt guide & pro tips

Describe what changes, not what is already there

Everything visible in the opening frame is set by the image. Spend the prompt on who moves, in which direction and how fast, then on the camera and any change in light. The candlelit-tub prompt starts with the first action ("She pushes up off the rim of the tub") and ends on "Slow drift-in, warm candle light only".

Name the landing when you send a closing frame

With last_image_url, say in the prompt that the shot ends on the supplied final frame and describe what happens on the way there. The bonfire brief does exactly this: "Begin on the two of them on the beach at sunset and end on the supplied final frame". Keep subject, wardrobe and light continuous between the two images before you write anything.

Scale duration to the distance travelled

The single-action examples run 5 seconds; the sunset-to-night transition uses 10. Start with a short clip and review subject, edges, light and camera continuity across the whole output before lengthening it. Scrub water shots such as the pool example frame by frame, because water is where an animated still usually falls apart.

Direct the sound and lock the seed

Because audio is always generated, write the sound into the prompt: the pool brief asks for "no music, only muffled underwater tone". When the motion is right, keep seed and the prompt fixed and raise only resolution. The seed makes runs comparable, not frame-identical, so check the final render again at full resolution.

API quick start

Call the LTX 2.5 API in three steps

1. Create an API key. Sign in to PopNow and create a key in the API console. Keys start with sk-popnow- and use the same credits as the website.
2. Send the request. POST /jobs/createTask with model lightricks/ltx-2.5/image-to-video and an input object that follows the parameter table. The response returns a task ID straight away.
3. Get the result. Poll GET /jobs/recordInfo with the task ID, or pass a callBackUrl and we post the result to it. Download the output links when the task succeeds.

# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "lightricks/ltx-2.5/image-to-video",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
    "resolution": "720p",
    "duration_seconds": 5
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Replace the prompt and any links with your own. The API tab has the response, polling and callback reference.

LTX 2.5 API questions

All LTX models

MiniMax H3 covers more shapes and adds reference photos, but stops at 15 seconds. LTX 2.5 is the pick for 20-second takes and native 4K.

• LTX 2.5 APILong 20-second takes up to 4K with a soundtrackFrom 68 credits for a 5-second clip
• LTX-2.3 LoRA APILTX-2.3 clips with stereo sound and your own LoRAsFrom 18 credits for a 5-second clip
• LTX-2 19B API20-second clips with voices, music and effectsFrom 11 credits for a 5-second clip
• LTX-2 19B LoRA APILTX-2 clips with sound and your own LoRA stylesFrom 14 credits for a 5-second clip

Other video APIs

• MiniMax H3 APIExpressive clips with audio, up to 2KFrom 28 credits for a 5-second clip
• Seedance 2.5 APIByteDance's newest: 30-second clips with native audioFrom 56 credits for a 5-second clip
• Kling 3.0 API4K clips, multi-shot cuts and motion controlFrom 51 credits for a 5-second clip
• Vidu Q4 Preview APIUp to 4K clips with sound and spoken dialogueFrom 34 credits for a 5-second clip
• Wan 3.0 APIUp to 30-second clips with synced audioFrom 34 credits for a 5-second clip
• Kling O3 APIKling’s unified model: create, animate, reference and edit up to 4KFrom 51 credits for a 5-second clip

More about LTX 2.5

Try it

LTX 2.5 AI Video Generator onlineCreate videos with LTX 2.5 in PopNow

Docs

LTX 2.5 model ID and input schema in the API docsPopNow API quickstart: your first request in five minutesImage to video guide for the PopNow APIWebhooks: get LTX 2.5 results without polling