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Automatically generate or source relevant B-roll that matches what’s being said in your video, helping you increase visual variety, storytelling quality, and audience retention. AI B-roll is especially useful for talking-head videos, interviews, podcasts, explainers, and educational content that benefit from visual support.

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How It Works

The AI B-Roll tile analyzes your video’s speech, plans relevant visual cutaways, generates short video clips, and overlays them at appropriate timestamps. You can control:
  • B-roll density
  • Video generation model
  • Aspect ratio
  • Whether generated clips include audio
  • Maximum number of generated clips
  • Visual style and content focus

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Input & Settings

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Coverage Level

Defines how much B-roll gets added per minute. Options include (may vary by build):
  • Minimal
  • Moderate ← Balanced default
  • High
  • Maximal
Use Minimal for subtle enhancement and Maximal for heavy coverage.

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Video Model

Select which AI model to generate B-roll with. Supported API values:
  • seedance-2
  • veo-3.1
  • veo-3.1-fast
  • veo-3.1-lite
Different models produce different visual styles (cinematic, realistic, stylized, etc.).

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Aspect Ratio

Controls the shape of generated B-roll. Options:
  • Auto (recommended) → Matches your input video or target platform
  • 16:9 for YouTube/desktop
  • 9:16 for TikTok/Reels/Shorts Choose based on your final output format.

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Generate Audio (Optional)

Toggle to include audio in the generated B-roll. Notes:
  • Not all models support audio
  • Useful for cinematic segments
  • Not required for overlay-style B-roll

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Max Video Generations

Sets the max number of B-roll scenes to create. The backend caps this at 20 generated clips for deterministic runtime.

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Style & Content Prompt (Optional)

Use this to define:
  • Visual style
  • Subject matter
  • Tone / vibe
Examples:
  • “Cinematic city skyline shots, wide angle, slow motion”
  • “Stock footage of office work and laptops, clean and modern”
  • “Playful animated visuals matching educational content”
  • “Nature and planet shots, documentary style”
Leave blank to let Mosaic choose based on content.

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Usage Recommendations

Use AI B-roll to:
  • Break up long talking segments
  • Add visual context to explanations
  • Support storytelling
  • Improve audience retention
AI B-roll works great when combined with:
  • Clips (extract highlights first)
  • Reframe (convert to 9:16 for TikTok)
  • Captions (add subtitles)
  • AI Music (background audio)

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API Info

  • Node ID: 2160392b-ebe8-4f3d-b81e-fd11bdbbeb77

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Node params

ParamTypeRequiredDefaultNotes
coverage_level"low" | "moderate" | "high" | "max"No"moderate"Amount/frequency of generated B-roll.
promptstringNo""Optional visual/style guidance.
video_model"seedance-2" | "veo-3.1" | "veo-3.1-fast" | "veo-3.1-lite"No"seedance-2"Model choice for generated B-roll clips.
asset_types("video")[]No["video"]Fixed to video generation in current implementation.
aspect_ratio"auto" | "16:9" | "9:16"No"auto"Generated clip framing mode.
generate_audiobooleanNofalseInclude audio in generated clips when supported by the selected model.
max_video_generationsnumberNo20 effectiveUI/metadata may allow higher values; backend hard cap is 20.

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Parameter groups

  • Coverage strategy: coverage_level, max_video_generations
  • Generation model: video_model, asset_types, aspect_ratio, generate_audio
  • Creative guidance: prompt

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Scenario requirements

  • Keep max_video_generations within 1..20 for deterministic behavior.
  • Some model/aspect combinations are rejected by backend validators.

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Runtime notes

  • coverage_level controls target placement density and minimum gaps.
  • max_video_generations is capped at 20.

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Example

{
  "coverage_level": "moderate",
  "video_model": "seedance-2",
  "aspect_ratio": "9:16",
  "generate_audio": false,
  "max_video_generations": 10,
  "prompt": "Add short cinematic cutaways that reinforce key points."
}