Veo3.1-fast-extend-video is a specialized video extension model developed by Google DeepMind as part of the Veo 3.1 family, released in public preview on October 15, 2025. It enables seamless continuation of existing Veo-generated videos by appending new segments based on text prompts, preserving visual quality, motion continuity, scene consistency, lighting, and style. The model analyzes the last second of the input video to generate coherent extensions, making it suitable for building longer narratives from short clips.

Key features include fixed 7-second extensions at 720p resolution, support for 16: 9 or 9:16 aspect ratios, optional audio generation, and natural motion continuation. It outputs a single merged MP4 file combining the original and extended content, optimized for low-latency inference to facilitate rapid prototyping and iteration. The underlying technology leverages Google DeepMind's generative video architecture, enhanced for video-to-video workflows with improved prompt adherence and cinematic transitions compared to prior versions.

What makes it unique is its focus on high-speed extensions specifically for Veo-created inputs, enabling videos up to 30 seconds through iterative applications while maintaining fidelity in style, motion, and ambiance. This positions it as a tool for quick content creation in storytelling, social media, and advertising, trading higher resolutions for superior speed and coherence.

• Architecture: Google DeepMind Veo 3.1 Fast generative video model (video-to-video extension)
• Parameters: Not publicly disclosed
• Resolution: 720p (input and output); supports 1080p inputs
• Input/Output formats: Input: MP4, MOV, WebM, M4V, GIF via URL (up to 8 seconds, Veo-generated preferred); Output: Single merged MP4 video
• Performance metrics: 7-second extension duration; low-latency inference optimized for rapid iteration; audio synchronization with visuals

• Input videos must be originally produced by Veo 3.1 for optimal results, with strict limits on length (up to 8 seconds) and resolution (720p or 1080p in 16:9 or 9:16)
• Best practices: Include action, style, camera motion, and ambiance in prompts; use "auto" aspect ratio and resolution for flexibility; enable audio generation for synchronized outputs
• Common pitfalls: Non-Veo inputs may reduce continuity; safety filters applied to inputs and outputs can reject prompts
• Quality vs speed trade-offs: Prioritizes fast inference over ultra-high resolution, ideal for prototyping before high-res renders
• Prompt engineering tips: Describe "what should happen next" precisely; reference maintaining style/motion explicitly, e.g., "Continue the scene naturally, maintaining the same style and motion"

• Optimal parameter settings: Set duration to "7s", resolution to "720p", aspectratio to "auto", generateaudio to true for full fidelity
• Prompt structuring advice: Start with continuation directive (e.g., "Continue seamlessly"), specify action/style/camera, end with mood (e.g., "cinematic lighting, smooth pan right")
• How to achieve specific results: For social media, use 9:16 ratio; for natural flow, prompt "preserve exact motion and lighting from last frame"
• Iterative refinement: Extend in 7s steps to reach 30s; refine prompts progressively based on outputs, e.g., build on previous extension's details
• Advanced techniques: Combine with image references (up to three) for precise scene control; use auto_fix for policy-compliant prompt rewrites

• Seamless 7-second video extensions with natural motion, style, and scene continuity
• Analyzes last second of input for coherent frame generation
• Supports text-guided extensions including camera motion, ambiance, and style transitions
• Generates synchronized native audio with visuals
• High-quality cinematic outputs at 720p, suitable for merged sequences up to 30s via iteration
• Versatile for both video-to-video and text-to-video modes with improved prompt adherence over prior versions
• Optimized for low-latency, high-volume content creation

• Rapid prototyping of narrative flows and storyboards by extending short clips iteratively
• Social media content like Shorts and Reels, with quick 7s additions in vertical formats
• Advertising and creative editing, maintaining realistic motion/lighting for seamless shots
• High-turnaround AI video for developers testing continuity concepts
• Building longer cinematic sequences from initial Veo clips in storytelling workflows

• Experimental public preview status with features like image referencing and first/last frame control
• Known quirks: Best with Veo-originated inputs; may vary continuity on non-Veo videos
• Performance: Low-latency for fast iteration, but fixed 7s extensions require multiple runs for longer videos
• Resource requirements: Queue-based for long-running requests; webhooks recommended for results
• Consistency: Strong preservation of motion/lighting; users note excellent synchronization
• Positive feedback: Improved over older Veo in prompt adherence, audio sync, and transitions
• Common concerns: Safety filters may block prompts; input format strictness

• Fixed 7-second extensions only, requiring iteration for longer videos (up to 30s max practical)
• Optimized for 720p speed; lacks ultra-high resolutions; input must match specific formats/resolutions/aspect ratios
• Restricted to Veo-generated inputs for best results; safety filters limit certain content