What is Veo 3.1-Fast?
Veo 3.1-Fast is a speed-optimized version of Google's Veo 3.1 series of generative video models. It's specifically optimized to reduce latency and cost for short videos (suitable for social media playback) while retaining the higher audiovisual fidelity introduced in Veo 3.1. Compared to previous Veo versions, Veo 3.1 and Veo 3.1-Fast add richer native audio generation capabilities, stronger cue-following capabilities, and new editing workflows (e.g., first/last frame interpolation, "video footage," and scene expansion).
Core Features
Model Series/Architecture (Overview): Veo 3.1 is a spatiotemporal generative video model in the Veo series (publicly cited as being based on diffusion and Transformer design patterns), integrating audiovisual composition and dedicated tools for editing/expansion.
Native Audio and Synchronization: A key feature of Veo 3.1 is richer, more context-aware native audio: dialogue, ambient sounds, and sound effects are generated synchronously with visuals (this audio capability has been extended to the photo → video workflow and editing/expansion features).
Latency/Throughput (Engineering Trade-offs): Compared to the Quality-First version, the "Fast" version is optimized for lower latency and cost per second of video; this optimization typically results in significantly reduced generation time (various real-world reports and vendor notes indicate approximately 2x speedup in typical short-video scenarios, depending on resolution and payload). Exact runtime will vary depending on infrastructure tier, resolution, and queue.
Technical Specifications
Primary Uses: Rapidly generate text → video and image → video for concise, high-speed creative workflows—prototyping, social media shorts, and in-app generation.
Typical Output Length (Permitted): The Veo 3.1 series supports fixed-length short videos; the API offers 4-second, 6-second, and 8-second options and supports controlled extended workflows (extending scenes via small "jumps"). These length options and the scene extension mechanism released in Veo 3.1 are listed in the public documentation and changelog.
Resolution and Aspect Ratio: Standard output includes 720p and (16:9 aspect ratio) 1080p, 4K; both 16:9 and 9:16 aspect ratios are supported (9:16 is primarily for mobile/social platforms).
Input: Free text hints, optional reference images (Veo 3.1 supports up to multiple images), and explicit start/end frames for interpolation or continuation from the last frame in some editing workflows.
How to Access the Veo 3.1 Quick API
Step 1: Register an API Key
Log in to cometapi.com. If you are not yet a user, please register first. Log in to your CometAPI console. Obtain the API key, your access credential. In your profile, under API Tokens, click "Add Token," obtain the token key: sk-xxxxx, and submit.
Step 2: Send a Request to the Veo 3.1 Fast API
Select the "\veo3.1-fast\" endpoint to send an API request and set the request body. The request method and body can be found in our website's API documentation. For convenience, our website also provides the Apifox testing tool. Please replace with your actual CometAPI key in your account.
Enter your video hints or reference images in the Content field (you can upload them or use a URL)—the model will respond to this. Process the API response to obtain the generated answer. Generate Veo3 videos asynchronously via POST /v1/videos in CometAPI, returning a task id and supporting first/last-frame guidance for up to 8-second clips.
Alternatively, you can use the playground on our Veo 3.1 Fast model page to easily and quickly generate videos without programming.
Step 3: Retrieve and Verify the Results
After a short wait, the video will be generated. The API response will provide a video link; please download it promptly.
For more information about Veo 3.1, please refer to the veo video doc.