Grok Imagine is the better default for most developers at $0.07/second with native audio and a full creative pipeline, while Veo 3.1 earns its premium for 4K output, granular controls, and a Lite tier at $0.05/second that undercuts Grok on cost.
This guide breaks down Grok Imagine vs. Veo 3.1, covering architecture, motion quality, native audio, speed, pricing, editing workflows, and the specific video production scenarios each model handles best.
TL;DR
Grok Imagine is the better default for most developers building video pipelines.
It generates 720p video with native audio at $0.07 per second on fal, and generation times appear to be roughly 17 seconds per clip.
It also covers the full creative chain: text-to-image, image editing, text-to-video, image-to-video, video editing, and video extension, all under a single model family.
Veo 3.1 earns its premium when you need higher resolution ceilings (up to 4K), finer control over generation parameters (negative prompts, seed, safety tolerance), or Google DeepMind's top-tier visual fidelity.
An 8-second clip with audio at 720p costs $3.20 on the standard tier, but the broader Veo 3.1 family includes a Lite tier at $0.05 per second with audio at 720p, which actually undercuts Grok Imagine on a per-second cost.
Here's how they stack up:
| Grok Imagine | Veo 3.1 | |
|---|---|---|
| Creator | xAI | Google DeepMind |
| Architecture | Aurora autoregressive engine | Latent Diffusion Transformer (DiT) with spatio-temporal patches |
| Best for | Fast, cost-effective video with audio, broad aspect ratio coverage, full creative pipeline (images and video) | Maximum visual fidelity, 4K output, granular generation control |
| Price per second (720p, with audio) | $0.07/s | $0.40/s (standard), $0.15/s (fast), $0.05/s (lite) |
| Price per second (480p) | $0.05/s | N/A |
| Max output resolution | 720p | 4K |
| Max output duration | Up to 10 seconds | 8 seconds |
| Native audio | ✅ Always on (dialogue, ambient, SFX) | ✅ Toggle on or off (dialogue, ambient, SFX) |
| Aspect ratios | 16:9, 4:3, 3:2, 1:1, 2:3, 3:4, 9:16 | 16:9, 9:16 |
| Input types | Text-to-video, image-to-video, reference-to-video (up to 7 images), edit-video, extend-video | Text-to-video, image-to-video, first/last-frame-to-video, reference-to-video, extend-video |
| Negative prompts | ❌ | ✅ |
| Seed control | ❌ | ✅ |
| Safety tolerance levels | ❌ | ✅ (1-6, API only) |
| Video editing | ✅ Native edit-video endpoint | ❌ |
| Video extension | ✅ Extend-video endpoint | ✅ Extend-video endpoint (standard and fast tiers) |
| Image generation | ✅ Text-to-image ($0.02/image), image editing ($0.022/image) | ❌ Video only |
| Output format | MP4 (24 fps) | MP4 (24 fps) |
| Watermarking | Per xAI terms | SynthID |
| Commercial use | ✅ | ✅ |
What is Grok Imagine's & Veo 3.1's approach to generating videos?
Grok Imagine and Veo 3.1 take fundamentally different approaches to generating video.
That's the first thing worth understanding, as it shapes everything from how they handle motion to how they synchronize audio.
Grok Imagine runs on xAI's Aurora engine, an autoregressive architecture.
Autoregressive means the model predicts video frames sequentially, one after another, rather than generating the entire clip at once.
This approach gives tighter control over frame-to-frame transitions and is what enables Aurora's native audio-video synchronization.
The model treats each frame as the logical next step in a sequence, similar to how large language models predict the next token.
Veo 3.1, built by Google DeepMind, uses a latent diffusion transformer architecture.
It compresses video data into spatio-temporal patches and processes time as a third spatial dimension alongside width and height.
Instead of predicting frames one by one, Veo 3.1 generates the video as a unified three-dimensional volume.
This means that every pixel's position and appearance throughout the entire duration simultaneously influence the final output.
The practical result of this split?
Aurora's sequential approach tends to produce fast generation with strong temporal coherence in motion.
Veo 3.1's volumetric approach tends to produce richer spatial detail and more physically consistent environments.
Both models generate audio natively alongside video in a single pass.
But the underlying mechanics are different:
Aurora bakes audio into the sequential prediction pipeline, while Veo 3.1 trains a dedicated audio layer jointly with its video model.
Side-by-Side: Video Comparison Tests
To see how these differences play out visually, here are head-to-head generations from Grok Imagine and Veo 3.1 using identical prompts on fal.
Test 1: Simple Motion with a Single Subject
Prompt: "A golden retriever runs along a beach shoreline at sunset, kicking up wet sand, camera tracking alongside at eye level, warm golden light, shallow depth of field"
Grok Imagine:
Generated using Grok Imagine on fal, an AI model from xAI.
Veo 3.1:
Generated using Veo 3.1 on fal, an AI model from Google DeepMind.
Test 2: Complex Multi-Element Scene with Audio
Prompt: "A barista in a busy coffee shop steams milk while two customers chat at the counter, espresso machine hissing, cups clinking, soft jazz playing from a speaker in the corner, medium shot with shallow depth of field, warm interior lighting"
Grok Imagine:
Generated using Grok Imagine on fal, an AI model from xAI.
Veo 3.1:
Generated using Veo 3.1 on fal, an AI model from Google DeepMind.
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Test 3: Cinematic Camera Work
Prompt: "A slow tracking shot follows a lone figure in a dark coat walking down a rain-soaked Tokyo alley at night, neon signs reflecting off wet pavement, steam rising from a street vent, shallow depth of field, anamorphic lens flare, ambient rain and distant traffic sounds"
Grok Imagine:
Generated using Grok Imagine on fal, an AI model from xAI.
Veo 3.1:
Generated using Veo 3.1 on fal, an AI model from Google DeepMind.
What is the difference in Grok Imagine's and Veo 3.1's pricing?
The per-second cost difference between Grok Imagine and Veo 3.1 is significant at the flagship tier.
But the Veo 3.1 family spans a wide price range, and the cheapest tier actually undercuts Grok Imagine.
Grok Imagine pricing on fal
Here's how much it'd cost you to use Grok Imagine on fal:
Text-to-video: $0.05 per second at 480p, $0.07 per second at 720p.
Image-to-video: same per-second rate as text-to-video, plus $0.002 per input image.
Reference-to-video (up to 7 reference images): same per-second rate, plus $0.002 per input image.
Edit-video: $0.05 per second of output plus $0.01 per second of input at 480p. At 720p, that's $0.07 per second of output plus $0.01 per second of input.
Extend-video: same pricing structure as edit-video.
For example, an 8-second 720p clip would cost $0.56, and a 10-second 720p clip would cost you $0.70.
Veo 3.1 pricing on fal
Here's how much it'd cost you to use Veo 3.1 on fal:
Standard tier (highest quality):
720p or 1080p: $0.20 per second without audio, $0.40 per second with audio.
4K: $0.40 per second without audio, $0.60 per second with audio.
An 8-second 720p clip with audio would cost you $3.20.
Fast tier (balanced speed and cost):
720p or 1080p: $0.10 per second without audio, $0.15 per second with audio.
4K: $0.30 per second without audio, $0.35 per second with audio.
An 8-second 720p clip with audio costs $1.20.
Lite tier (budget-optimized):
720p: $0.03 per second without audio, $0.05 per second with audio.
1080p: $0.05 per second without audio, $0.08 per second with audio.
An 8-second 720p clip with audio would cost you $0.40.
What this looks like at scale
For a team generating 100 eight-second clips per month at 720p with audio:
Grok Imagine costs $56 (100 clips at $0.56 each).
Veo 3.1 standard costs $320 (100 clips at $3.20 each).
Veo 3.1 Fast costs $120 (100 clips at $1.20 each).
Veo 3.1 Lite costs $40 (100 clips at $0.40 each).
At 1,000 clips per month, Grok Imagine runs $560 while Veo 3.1 Lite runs $400.
💡 You can use Veo 3.1 Lite for high-volume draft generations at $0.05 per second, route clips that need editing through Grok Imagine, and reserve Veo 3.1 standard for 4K deliverables that justify the $0.60 per second premium.
How Is Veo 3.1 Different from Grok Imagine?
Resolution ceiling
Veo 3.1 supports 4K output on the standard and fast tiers, and 1080p on the lite tier.
Grok Imagine's maximum resolution is 720p.
For any workflow that requires higher-resolution deliverables, whether for broadcast, large-screen display, or archival quality, Veo 3.1 is the only option between the two.
Generation control parameters
Veo 3.1 exposes several controls that Grok Imagine doesn't.
Negative prompts let you specify what you don't want in the output, which is useful for avoiding specific visual artifacts or content.
Seed control enables reproducible generations, so you can lock in a result and iterate on the prompt while keeping the same visual base.
Safety tolerance (1-6, API only) gives developers fine-grained control over content moderation levels.
And the auto-fix parameter can automatically rewrite prompts that fail content policy checks.
Grok Imagine's API is simpler by design: prompt, duration, aspect ratio, resolution. That's it.
First and last frame control
Veo 3.1 offers a first-and-last-frame-to-video endpoint, available on both the standard and fast tiers.
You provide two images (the opening and closing frames) plus a text prompt, and the model interpolates the video between them.
This is a specific workflow advantage for storyboard-driven production, where you already know where a shot starts and ends.
Grok Imagine doesn't have this endpoint.
But its reference-to-video endpoint accepts up to 7 reference images to guide the generation, which serves a different but related use case: style and content guidance rather than exact start-and-end-frame interpolation.
Audio toggle
Both models generate audio natively.
But Veo 3.1 lets you turn audio off, which drops the per-second cost significantly (from $0.40 to $0.20 on the standard tier at 720p or 1080p).
Grok Imagine's audio is always on.
If you're generating silent video for workflows where you'll add your own audio track in post, Veo 3.1's toggle saves money.
Aspect ratio coverage
Grok Imagine supports seven aspect ratios for video: 16:9, 4:3, 3:2, 1:1, 2:3, 3:4, and 9:16.
Veo 3.1 supports two: 16:9 and 9:16.
If you're producing for platforms that require 4:3, 1:1, or 3:2 output, Grok Imagine handles those natively.
With Veo 3.1, you'd need to crop or pad the output in post.
Grok Imagine's creative pipeline breadth
Grok Imagine is more than a video model.
It's a unified creative engine covering text-to-image ($0.02 per image), image editing ($0.022 per image), text-to-video, image-to-video, reference-to-video, video editing, and video extension, all under a single model family.
If your workflow involves generating a still concept, refining it with editing, then animating it as video, Grok Imagine can handle that entire chain without switching models.
How to Run Both Models on fal
You can run Grok Imagine and Veo 3.1 through fal's API or test them in the playground at fal.
Same integration pattern across both models.
If you've already integrated one, switching to the other is a one-line endpoint change.
import { fal } from "@fal-ai/client";
// Grok Imagine — text-to-video
const grokResult = await fal.subscribe("xai/grok-imagine-video/text-to-video", {
input: {
prompt:
"A ceramic vase on a sunlit windowsill, curtains drifting in a light breeze, dust particles floating in the warm light",
duration: 6,
aspect_ratio: "16:9",
resolution: "720p",
},
});
// Veo 3.1 — same pattern, different endpoint
const veoResult = await fal.subscribe("fal-ai/veo3.1", {
input: {
prompt:
"A ceramic vase on a sunlit windowsill, curtains drifting in a light breeze, dust particles floating in the warm light",
duration: "8s",
aspect_ratio: "16:9",
resolution: "720p",
generate_audio: true,
},
});
Both models work with the same API structure on fal.
That means you can build a routing system where budget-sensitive requests go to Grok Imagine, and 4K deliverables go to Veo 3.1 with nothing but a string swap.
When to Use Grok Imagine vs. Veo 3.1? A Decision Framework
Rather than declaring a winner, here's how I'd think about routing between the two.
Choose Grok Imagine when
You need video with native audio at the lowest flagship cost ($0.07 per second at 720p). Although Veo 3.1 Lite at $0.05/s with audio is cheaper.
Your production requires square, 4:3, or 3:2 aspect ratios that Veo 3.1 doesn't support natively.
You want a single model family covering images, video, editing, and extension without switching APIs.
You're editing existing video through natural language prompts (edit-video endpoint).
Your workflow starts from a still image and moves through editing to video, all within one pipeline.
Choose Veo 3.1 when
Your deliverables require 1080p or 4K resolution.
You need negative prompts to exclude specific elements from the output.
Reproducibility matters and you need seed control for consistent generations.
You're working with storyboards and want first-and-last-frame-to-video interpolation.
Your workflow generates silent video where turning off audio cuts costs in half.
You want the cheapest per-second rate available (Veo 3.1 Lite at $0.05 per second with audio, $0.03 without).
Use both
Use both when you want to route high-volume draft work through Veo 3.1 Lite at $0.05 per second, then send clips that need editing, extension, or broader aspect ratios through Grok Imagine at $0.07 per second, and reserve Veo 3.1 standard for 4K hero content at $0.60 per second.
Since both models are accessible through the same API structure on fal, this routing logic takes minutes to implement.
Recently Added
Run Grok Imagine and Veo 3.1 on fal
AI video generation has more capable models now than at any point in the past year, with native audio, 4K output, and editing workflows that didn't exist six months ago.
And that's the challenge: picking the right one for each use case requires testing, which costs time and credits.
If you want access to both Grok Imagine and Veo 3.1 through a single API with pay-per-use pricing and no GPU management, fal is the fastest way to get started.
Test either model in the playground or plug into the API in minutes.
Grok Imagine vs. Veo 3.1: FAQs
How much does it cost to generate an 8-second video with Grok Imagine vs. Veo 3.1?
An 8-second 720p clip with audio costs $0.56 on Grok Imagine.
The same clip on Veo 3.1 costs $3.20 on the standard tier, $1.20 on the fast tier, or $0.40 on the lite tier.
All pricing is pay-per-second on fal with no minimums or subscriptions.
Can Grok Imagine and Veo 3.1 generate audio?
Yes.
Both Grok Imagine and Veo 3.1 generate synchronized audio natively alongside video in a single pass, including dialogue, ambient sounds, and sound effects.
The difference is that Veo 3.1 lets you toggle audio off to reduce cost (from $0.40 to $0.20 per second on the standard tier at 720p or 1080p), while Grok Imagine's audio is always on.
Which model between Grok Imagine and Veo 3.1 supports higher resolution output?
Veo 3.1 supports 720p, 1080p, and 4K output on the standard and fast tiers, and 720p or 1080p on the lite tier.
Grok Imagine generates at 480p or 720p.
If your workflow requires anything above 720p, Veo 3.1 is the only option between the two.
Can I run both Grok Imagine and Veo 3.1 through a single API?
Yes.
Both Grok Imagine and Veo 3.1 are available on fal through the same JavaScript and Python SDKs.
The integration pattern is identical: you call fal.subscribe() with the model's endpoint string, and switching between models is a one-line change.
You can test both in the fal playground before writing any code.
Which model between Grok Imagine and Veo 3.1 has more aspect ratio options for video?
Grok Imagine supports seven aspect ratios: 16:9, 4:3, 3:2, 1:1, 2:3, 3:4, and 9:16.
Veo 3.1 supports two: 16:9 and 9:16.
If you're producing content for platforms that need square (1:1), 4:3, or 3:2 output, Grok Imagine handles those natively without post-production cropping.
