H3 mixing camera, character and audio from three inputs

MiniMax describes H3 as using unified context across text, images, video and audio, with an example that applies camera movement from one video while a character from an image sings with audio from another source. Sume's minimax-h3 accepts image, video and audio references, and audio must be paired with at least one image or video reference.

What MiniMax says

From the MiniMax H3 post, read on 2026-10-03: H3 takes a unified context of text, images, video and audio. The example given combines three inputs, each contributing something different.

What Sume exposes

Limits are per model. minimax-h3 accepts 5 to 15 seconds at native 480p and 768p; 768p is first-class, not 720p. Audio and video references are honored by the Seedance 2.x models, Wan 3.0, MiniMax H3 and MiniMax H3 Max. Confirm what a model accepts by reading supported_input_references from GET /v1/videos/models.

In the flat Video Router fields, reference_audio_urls requires at least one image or video reference. So the audio-only case is not valid; the three-input mix is.

Submit the mix

This uses the Video Router wire with flat reference fields. All media must be public HTTPS URLs. Reuse the Idempotency-Key on retries.

curl -X POST https://api.sume.com/v1/video-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: h3-mix-001" \
  -d '{
    "model": "minimax-h3",
    "prompt": "The character from the image sings, with the camera move of the reference video",
    "reference_image_urls": ["https://example.com/character.png"],
    "reference_video_urls": ["https://example.com/camera-move.mp4"],
    "reference_audio_urls": ["https://example.com/song.mp3"],
    "resolution": "768p",
    "duration": 8,
    "mode": "async"
  }'

Set expectations

A prompt describing all three roles helps, but the docs do not promise that a reference is copied exactly. Treat the output as a take to review. Read capabilities from the model catalog before assuming one envelope, since limits differ between H3, H3 Max and other models.

• Keep the audio within the clip length you request.
• Use a short test at 5 seconds before a longer run.
• Poll the job and read usage.cost on the receipt.