Video extension

Multimodal

Unlike editing, extension doesn't modify your clip — it generates new footage that carries on from its final frames. Send the clip as exactly one input_video_references entry plus a prompt describing what happens next, with a duration_secs of 5–15 and a resolution of 720p or 1080p.

curl https://videorouter.sh/api/v1/videos \
  -H "Authorization: Bearer llmr_sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "model": "flux-3-extend",
    "prompt": "the camera slowly pulls back to reveal the whole city",
    "input_video_references": [
      {"type": "video_url", "video_url": {"url": "https://example.com/source-clip.mp4"}}
    ],
    "duration_secs": 8,
    "resolution": "720p"
  }'

ModelProviderNotes

flux-3-extendBlack Forest Labs (direct; also Fal, Atlas Cloud as failover)FLUX 3 continuation. 5–15s (Fal/Atlas up to 20s). $0.41/s at 720p, $0.53/s at 1080p

atlascloud/wan-2.5-extendAtlas CloudWan 2.5, with audio. 5–10s. $0.0525/s (480p), $0.105/s (720p), $0.1575/s (1080p)

atlascloud/pixverse-v6-extendAtlas CloudPixVerse v6. 1–15s. $0.025/s (360p) to $0.09/s (1080p)

atlascloud/grok-imagine-video-extendAtlas CloudxAI Grok Imagine. Source clip 2–15s, extension 2–10s, 720p cap. $0.07/s of extension plus $0.01/s of the source clip

fal/veo-3.1-fast-extendFalVeo 3.1 Fast. Adds a fixed 7s. $0.15/s. Only extends clips generated by Veo (720p/1080p, 16:9 or 9:16)

fal/veo-3.1-extendFalVeo 3.1. Adds a fixed 7s. $0.40/s. Same Veo-generated-source requirement

All of them take the same request: one input_video_references clip plus a prompt. Billing is on the output seconds (the input clip isn't charged, except Grok's small per-second source-clip fee noted above), before our platform fee. Atlas Cloud rows settle from Atlas Cloud's own reported cost on the finished job. resolution accepts only the tiers each model supports.