Best AI Video Generation API in 2026: Comparing hiapi's Four Video Models

If you're building anything with AI-generated video in 2026 — product demos, ad creative, animated stills, social loops — the per-second cost is now the dominant variable in your unit economics. A five-second 1080p clip can cost you $0.84 or $4.12 depending on which model you call, and the picture-quality gap doesn't scale linearly with the price gap. So picking the right model for the right job is real money.

hiapi currently ships four video generation models on a unified async task API: wan2.7-t2v, wan2.7-i2v, happyhorse-1-0, and seedance-2-0. They span almost an order of magnitude in per-second cost. This piece compares them head-to-head on price, capabilities, intended use case, and gives you a decision tree at the end.

All numbers below are pulled directly from https://www.hiapi.ai/api/pricing on the date of publishing — if anything diverges, that endpoint is canonical.

The lineup at a glance

Model	Vendor	Modes	Resolutions	Per-sec 720p	Per-sec 1080p
wan2.7-t2v	Alibaba (Tongyi Wanxiang)	Text → Video	720P, 1080P	$0.100	$0.167
wan2.7-i2v	Alibaba (Tongyi Wanxiang)	Image → Video	720P, 1080P	$0.100	$0.167
happyhorse-1-0	HappyHorse	Text → Video	720p, 1080p	$0.168	$0.288
seedance-2-0	ByteDance (Doubao)	Text → Video and Image → Video	480p, 720p, 1080p	$0.330	$0.823

Two patterns jump out immediately:

• The wan2.7 family is the price floor for HD output on the platform. At $0.167/sec for 1080p, a typical 5-second clip costs $0.835.
• Seedance 2.0 is the price ceiling — almost 5× wan at 1080p. The cost premium is paid for cinematic motion quality, native audio, and the fact that a single model handles both text-to-video and image-to-video.

happyhorse-1-0 sits in the middle. It's 70% more expensive than wan at 1080p and 65% cheaper than seedance, which makes it the "stylized cinema, modest budget" pick.

Pricing math: what does a real clip cost?

Per-second pricing only matters once you fix a duration. Most production clips land in the 3–10 second range. Here are the totals you actually charge against budget:

5-second clip:

Model	480p	720p	1080p
wan2.7-t2v	—	$0.500	$0.835
wan2.7-i2v	—	$0.500	$0.835
happyhorse-1-0	—	$0.840	$1.440
seedance-2-0	$0.750	$1.650	$4.115

10-second clip:

Model	720p	1080p
wan2.7-t2v	$1.000	$1.670
wan2.7-i2v	$1.000	$1.670
happyhorse-1-0	$1.680	$2.880
seedance-2-0	$3.300	$8.230

Takeaway: if you're prototyping a flow that needs to render hundreds of variants — like ad creative A/B tests or programmatic product spins — wan2.7 at 720p ($0.10/sec) is roughly 3.3× cheaper per clip than seedance at the same resolution, and almost 5× cheaper at 1080p. That math compounds fast.

If you only call video once per finished asset (a single hero clip per landing page), the absolute cost difference is in the dollar range, not the cent range, and quality probably wins. Run the cost math against your call volume, not your unit cost.

Capability deep dive

The pricing table is one half of the story. The other half is what each model can actually do.

wan2.7-t2v — the HD workhorse

Alibaba's Tongyi Wanxiang 2.7 text-to-video model is the cheapest 1080p option on the platform. The hiapi listing flags it as supporting native audio output and clip lengths up to 15 seconds, which matters because not every text-to-video model on the market generates audio.

Where it earns its keep: high-volume jobs where you need real HD and don't want to pay for cinematic polish. Marketing collage clips, animated b-roll behind a presenter, looping ambient backgrounds, slideshow stings. Anywhere a 1080p clip with synchronized sound effects is "good enough."

wan2.7-i2v — animate the still you already have

Identical pricing to its t2v sibling. The difference is the input modality: instead of a text prompt alone, you give it a reference image (a still product photo, a character illustration, a frame from another shot) and a motion description, and it animates that frame.

This is the model you reach for when you already have approved key art and you just need it to move. Brand consistency is the whole game here — the t2v models won't reliably reproduce a character or product across clips, but i2v starts from the asset you've already locked in.

Practical use cases:

• E-commerce: animate a product hero shot (rotate, soft motion, parallax).
• Illustration-driven content: bring a static character pose to life for a 5-second social loop.
• Editorial: take an existing magazine spread photo and add subtle environmental motion (rain, wind, drifting smoke).

happyhorse-1-0 — the cinematic stylization tier

HappyHorse is the newcomer (badged "New" on the model directory and pinned in the top slot). The platform listing positions it for 720p–1080p output at 3–15 second durations with multi-aspect-ratio support, and the model's example prompt explicitly references "live-action cinematography, natural ambient lighting, 35mm film grain, shallow depth of field" plus on-clip audio cues (footsteps, distant bells, wind).

The marketing framing is "looks like film" rather than "looks generated." If your project needs that filmic register — short-form drama scenes, mood pieces, period stylization — happyhorse is the middle-priced choice that targets exactly that aesthetic. You're paying about $0.12/sec extra over wan at 1080p for the stylization upgrade.

When not to use it: pure utility clips (UI motion, abstract data visualization, animated logo reveals). The cinematic vocabulary doesn't help you there and you'd be paying for capability you don't need.

seedance-2-0 — the premium pick, both modalities in one

ByteDance's Seedance 2.0 is the only model in the lineup whose tags include both TEXT-TO-VIDEO and IMAGE-TO-VIDEO. With wan, you have to know up front which modality you need and call the matching endpoint; with seedance, the same model handles either.

The platform description claims "cinematic-grade visual quality, exceptional motion performance, native audio." The pricing reflects the positioning: $0.823/sec at 1080p is steeper than every alternative on the platform, but seedance is also the only one that offers a 480p tier ($0.15/sec) — which is interesting if you're doing rapid creative exploration where you want to iterate on motion and composition before committing to an HD render.

The use case profile:

• Hero shots and signature scenes where the clip is the asset and budget matters less than polish.
• Pitch decks, sizzle reels, paid-media headers where one clip carries the campaign.
• Mixed t2v/i2v workflows where you don't want to maintain two model integrations.
• Rapid creative iteration at 480p ($0.15/sec is cheaper than wan at 720p — useful if you can tolerate the resolution drop for storyboarding).

The trap: if your workflow is "generate 200 variants and pick three," seedance at 1080p is the wrong tool. Use a cheaper model for the variant pass, then upgrade the winners.

Decision tree

Distilling everything above into a single routing decision:

1. Are you animating an existing image?

   • Yes, and budget is tight → wan2.7-i2v at 1080p ($0.167/sec).
   • Yes, and quality matters more than cost → seedance-2-0 at 1080p ($0.823/sec).

2. Pure text-to-video, what's the use case?

   • Volume / programmatic / variant generation → wan2.7-t2v at 720p ($0.10/sec). Cheapest HD output with native audio.
   • Filmic stylization, drama, mood pieces → happyhorse-1-0 at 1080p ($0.288/sec). Cinematic register at a moderate premium.
   • Hero shots, paid creative, single high-stakes clip → seedance-2-0 at 1080p ($0.823/sec). Premium quality, native audio, both modalities in one model.

3. Storyboarding / rapid creative exploration? Render at 480p with seedance-2-0 ($0.15/sec, the same per-second cost as wan2.7 at 720p) — then re-render the winners at 1080p in the model that fits the final use case.

How you actually call them

All four models speak the same API — hiapi unified async task interface at POST /v1/tasks. You create a task, poll for completion, then download the output URL. Worth highlighting because in early 2026 the platform retired the older /v1/chat/completions and /v1/images/generations endpoints for video; the task API is the only path now.

# Create the task — same shape for all four models, just swap the model name.
curl https://api.hiapi.ai/v1/tasks \
  -H "Authorization: Bearer $HIAPI_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "wan2.7-t2v",
    "input": {
      "prompt": "A young woman in a white sweater sits by a coffee shop window, gently lifting her cup as raindrops trail down the glass. Warm yellow light on her face, cinematic shallow depth of field, 35mm film, slow-motion close-up.",
      "resolution": "1080P",
      "duration": 5
    }
  }'
# Response: { "data": { "taskId": "..." } }

# Poll until done.
curl https://api.hiapi.ai/v1/tasks/$TASK_ID \
  -H "Authorization: Bearer $HIAPI_TOKEN"
# Response: { "data": { "status": "success", "output": [{ "url": "https://..." }] } }

A few practical notes that bit us during integration testing:

• Output URLs are signed and time-limited. Download the bytes immediately and re-host (R2, S3, your CDN of choice) instead of hot-linking. Don't store the upstream URL — it will expire.
• Polling cadence: 5-second intervals is fine. Most clips finish in 60–180 seconds depending on duration and resolution.
• Set a real timeout. 600 seconds is a safe upper bound for 1080p; shorter clips finish much faster but a queue spike can push tail latency up.
• Errors come back with status: "fail" plus an error.code / error.message. Surface those to your queue, don't retry blindly — most failures are prompt issues, not transient, and retrying just doubles the bill.

The cost-per-finished-clip reality check

A useful exercise before you commit to a model: estimate your acceptance rate and divide cost by it. If you're generating 5-second 1080p clips and you keep 1 in 4, your true cost per finished clip is 4× the headline price.

Model	Cost per clip (1080p × 5s)	Cost at 25% accept rate	Cost at 50% accept rate
wan2.7-t2v / i2v	$0.84	$3.34	$1.67
happyhorse-1-0	$1.44	$5.76	$2.88
seedance-2-0	$4.12	$16.46	$8.23

For volume work where you'll burn through multiple takes per accepted clip, the gap widens — and the cheap models pull further ahead. For high-stakes single-clip work where you'd iterate the prompt carefully and probably keep the first one or two attempts, the gap is much narrower.

Bottom line

• Cheapest path to HD video on hiapi: wan2.7-t2v / wan2.7-i2v at 1080p, $0.167 per second. Use these as your default unless the project specifically calls for something else.
• Cinematic look at a moderate premium: happyhorse-1-0 at 1080p, $0.288 per second.
• Premium quality + native audio + unified t2v/i2v in one model: seedance-2-0 at 1080p, $0.823 per second. Worth it for hero clips, expensive overkill for variant generation.
• Storyboarding cheat: seedance-2-0 at 480p, $0.15 per second — drop resolution for creative exploration, then re-render winners in the right model.

All four ship behind one API, billed per second, no per-request setup. Pick by use case, not by brand affinity.