AI Video Generator API: Which Model to Pick in 2026

In short

Video models differ less in picture quality than in four things: maximum duration, sound, resolution and how you define the scene. Those are what you should choose by. An ordinary viewer won't notice the difference in the frame between top models, but will notice 8 seconds vs 15 right away.

Seven models are available today. In a nutshell:

• Animate a photo: Hailuo 2.3, that's exactly what it's for.
• A scene from text, with sound: Veo 3.1 or Kling.
• A long clip of up to 15 seconds: Kling 3.0, Wan 2.7 or Seedance 2.0.
• Lots of clips on a budget: Hailuo or Kling 2.6.

Below: how these parameters work, the full table and what you need to know to build generation into a product.

Two ways to define a scene

All video generation splits into two modes, and almost everything else depends on which one you pick.

Text-to-video. You describe the scene in words, and the model invents everything: composition, lighting, characters. More freedom, less predictability: the same wording gives different results.

Image-to-video. You provide the first frame, and the model adds the motion. The composition is yours; the model only invents the movement. Predictability is higher, and the prompt should describe not the picture but what happens in it.

The second mode is what people usually call "animate a photo". It's also the most popular request in this whole topic.

An important detail: not every model supports both modes. Hailuo 2.3 works only from an image. It has no text-to-video at all, and a request without a picture returns an error.

Four parameters to choose by

Duration

The range is wider than people expect: from 8 seconds on Veo to 15 on Kling 3.0, Wan 2.7 and Seedance.

In practice this means no model makes a one-minute video in one piece. Any long video is a set of scenes you edit together yourself. When you plan the work, count in scenes from the start.

Sound

There are three different situations here, and it's important not to mix them up:

• Sound included in the price: Veo 3.1, where the audio track is part of the main scenario.
• Sound for extra money: Kling, where turning it on doubles the per-second rate.
• Sound as an option: Wan 2.7, the track is there, but it's not the model's strong suit.

If you're going to put music on in editing anyway, there's no reason to generate sound. That's paying extra for nothing.

Resolution

From 480p to 4K, but be careful: on some models resolution is a price tier, not a setting. On Seedance both resolution and duration affect the price; on Kling 3.0 the std / pro / 4K modes are priced differently. Veo is fixed at 1080p, and 4K requires a separate call and costs more.

Aspect ratio

A small thing that tends to surface at the last minute. Not every model does vertical video: 9:16 is available on Veo, Kling and Seedance, and Seedance has the widest choice, all the way to 21:9. If you make content for vertical feeds, check this before you pick a model on other criteria.

All seven models

Prices are deliberately left out of this table: the models use different billing units, and comparing them in one row next to parameters is a good way to get it wrong. The full calculation per minute and per project is in a separate article.

How the models really differ

Hailuo 2.3 specializes narrowly in animating a frame: realistic motion, facial expressions, light. On people and faces it gives the best result for the money.

Kling 2.6 and 3.0 bring synchronized sound, speech and effects. Version 3.0 added multi-shot scenes of up to 15 seconds and a 4K mode. An API quirk: 3.0 requires an explicit multi-shot parameter, and without it the request won't go through.

Wan 2.7 Video is an all-rounder with negative_prompt and seed. The second one is underrated: seed gives you reproducibility, meaning you can repeat a good take instead of trying to catch it again.

Seedance 2.0 has strong consistency between frames, so the scene doesn't "drift". It has the widest choice of aspect ratios. It's noticeably more expensive than the other per-second models.

Veo 3.1 gives a cinematic frame with sound built into the model. It's billed per clip, not per second, so duration is effectively free: take the maximum and trim in editing.

How to build it into a product

The main difference between video and text or images: a render takes minutes, so the API is asynchronous. You create a job, get an id, then poll its status. The full request format is in the video API docs.

import time, requests

BASE = "https://api.altrouter.ai/v1"
H = {"Authorization": "Bearer sk-..."}

job = requests.post(f"{BASE}/videos", headers=H, json={
    "model": "kling-2.6",
    "prompt": "the camera slowly circles a cup of coffee on a table by the window, morning light",
    "duration": "5",
}).json()

while True:
    r = requests.get(f"{BASE}/videos/{job['id']}", headers=H).json()
    if r["status"] in ("completed", "failed"):
        break
    time.sleep(5)

print(r.get("url"), r["status"])

Four things to build into the architecture from day one.

A queue on your side. The user shouldn't wait several minutes for an HTTP response. Queue the job, return its id, show the status.

Poll every 3–5 seconds. Polling more often is pointless and runs into the rate limit.

The result link doesn't last forever. Download the finished clip to your own storage if you need it for longer than a single viewing.

Money is reserved when the job is created and charged only for a successful render. A failed render isn't charged.

What not to expect

These limitations are common to all the models, and it's better to know them in advance.

• Hands and fingers are the classic weakness. A close-up of hands will almost certainly take several attempts.
• Text in the frame smears as things move. Add captions in editing instead.
• You can't set a precise script with a prompt. A prompt is a wish, not a storyboard. Complex motion is easier to assemble from several short clips.
• Long clips drift. The further from the first frame, the more the model strays from the original composition.
• It won't work on the first try. Budget 2–3 renders per usable take. That's not pessimism, it's just how this genre works.

All seven models with current prices are in the model catalog. The $1 credited for a confirmed Telegram is enough for a trial run.

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