Reviewed 14 October 2026 against Runway, Adobe, Google and Descript documentation. HumanRank has not yet run a blind video quality test, so nothing on this page is a measured ranking.
Short answer
Google Veo 3.1 has the strongest documented specification of the three generators: 8-second clips at up to 4k with native audio. Runway Gen-4.5 is the simplest creative app, producing clips of 2 to 10 seconds at 720p. Adobe Firefly Video is the choice when you need partner models and video reference inside an Adobe workflow. If your footage already exists, you need an editor such as Descript, not a generator.
Decision table
| Need | Tool | Documented fact that matters | Main limitation | HumanRank score |
|---|---|---|---|---|
| Highest documented resolution | Google Veo 3.1 | 8-second clips at 720p, 1080p or 4k with native audio | Developer API; 1080p and 4k clips are 8 seconds only | Not tested |
| Quick creative clips | Runway Gen-4.5 | Text-to-video and image-to-video, 2 to 10 seconds | Output is 720p | Not tested |
| Adobe-centered production | Adobe Firefly Video | Partner models and a 5 to 10 second video reference | Maximum clip length not stated on current pages | Not tested |
| Editing real recordings | Descript | Edit audio and video by editing the transcript | Not a generator | Not tested |
The tools on the same fields
Google Veo 3.1
- Best for: developers and teams who need high resolution and generated sound.
- Documented strength: Google's Veo documentation describes 8-second videos at 720p, 1080p or 4k with natively generated audio. Veo 3.1 accepts up to 3 reference images, and Veo videos can be extended at 720p, 7 seconds at a time, up to about 148 seconds.
- Provenance: videos are watermarked with SynthID.
- Main limitation: lengths are 4, 6 or 8 seconds, and 1080p, 4k and reference-image clips must be 8 seconds. Generated videos are stored on the server for 2 days, so download them promptly.
Runway Gen-4.5
- Best for: creators who want to generate short shots in a browser app.
- Documented strength: Runway's help center lists text-to-video and image-to-video with clips of 2 to 10 seconds, at 24 or 25 frames per second. It costs 12 credits per second of video.
- Commercial use and provenance: Runway's terms say it does not restrict commercial use of your outputs, though it may train on inputs and outputs. Outputs from Runway's own models carry C2PA content credentials on every plan (product page).
- Main limitation: output is 720p, it runs on the web only, and it requires the Standard plan or higher. The help page does not mention audio generation.
Adobe Firefly Video
- Best for: teams already producing in Adobe tools who want a choice of models.
- Documented strength: Generate Video uses the Firefly Video model by default, and you can select partner models (Adobe help). A 5 to 10 second reference video can guide composition at 540p, 720p or 1080p.
- Provenance: Adobe said at launch that Firefly Video Model outputs include Content Credentials.
- Main limitation: generated video defaults to 24 fps. The current help pages we read do not state maximum clip length or whether Firefly's own model generates audio.
Descript (editing, not generation)
- Best for: podcasts, interviews and tutorials where the footage already exists.
- Documented strength: delete a word from the transcript, and that word disappears from your audio or video. Edits are non-destructive.
- Safeguard: Descript's Regenerate feature can change spoken words only when the original speaker has a custom AI speaker created and authorized in Descript.
- Main limitation: it does not create new footage from a prompt.
Generation and editing are different jobs
A generated clip is a new recording of something that never happened, so label and check it the way you would any synthetic media.
Generators create shots from text or images. Editors change recordings that already exist. Many productions need both: a generated establishing shot, then a cut of a real interview. Choose the generator for the shots you cannot film, and the editor for the material you have.
Watermarks and credentials
The three generators handle provenance differently. Google applies an invisible SynthID watermark to Veo videos. Runway attaches C2PA content credentials to outputs from its own models, and Adobe said Firefly Video outputs include Content Credentials. C2PA is an open technical standard for recording where content came from and how it was edited. Credentials show an intact history, not whether the scene is real. Our image generator guide explains Content Credentials in more detail.
How to test a video generator
- Write one shot list: a product turning on a table, a person walking toward the camera, and a scene with on-screen text.
- Generate each shot in two tools at the same length and aspect ratio.
- Check every frame, not only the first: hands, faces, text, object permanence and motion continuity.
- Check the file: resolution, frame rate, audio, and any watermark or credential.
- Estimate cost per usable second, counting the takes you discard.
Related categories
More categories in the HumanRank category index: best AI image generators, best AI chatbots and best AI writing tools.
Method and limits
- How we rank and how we are funded: our ranking method explains what a future HumanRank test will measure, and our disclosure explains which links may earn money.
- Sources: Google, Runway, Adobe and Descript documentation read on 14 October 2026, plus C2PA.
- Not tested: HumanRank has not yet measured motion quality, prompt adherence or continuity. Scores read "Not tested" until a published test exists.
- Not confirmed: Firefly Video's maximum clip length and audio support, Runway Gen-4.5 audio, and per-clip prices. We report only what current vendor pages state.
- Check the selected Google model. Google also lists a preview video model, Gemini Omni Flash, alongside Veo, so check which model a Google product is using.
Frequently asked questions
Which AI video generator makes the longest clips? Per generation, Runway Gen-4.5 documents up to 10 seconds and Veo 3.1 8 seconds. Veo can extend videos up to about 148 seconds at 720p.
Which AI video generator has the highest resolution? Google Veo 3.1 documents output up to 4k. Runway Gen-4.5 outputs 720p.
Does Veo generate sound? Yes. Google says Veo 3.1 produces natively generated audio, and audio is always on.
Can I use Runway videos commercially? Runway's terms say it does not restrict commercial use of outputs. It may train on your inputs and outputs.
Are AI-generated videos watermarked? Veo videos carry SynthID. Runway's own model outputs carry C2PA credentials, and Adobe says Firefly Video outputs include Content Credentials.
What is the difference between a video generator and a video editor? A generator creates new footage from prompts or images. An editor such as Descript changes recordings you already have.
Can Descript change what someone said? Only if the original speaker has a custom AI speaker created and authorized in Descript.
Can I guide a video with another video? Adobe Firefly accepts a 5 to 10 second reference video to guide composition.