Prepare the first image

1. How Vivix frames your starting image

Choose a starting image and set your session’s orientation and resolution. By default, Vivix scales the image to fill the session frame without stretching it, then crops any excess from around the center. An image that already matches the target size keeps its original framing.

For 720p portrait, Vivix keeps what’s inside the center frame and trims the shaded sides. The avatar’s head and hands stay in view.

Session output	Portrait	Landscape
480p	448 × 832	832 × 448
720p	672 × 1280	1280 × 672

Keep the face and hands near the center if you plan to use the same image in both orientations. To move the crop away from the center, see Create Session.

2. Keep the face clear

For realistic human subjects, aim for the face to occupy at least 7% of the image after cropping. Keep the whole face visible, from the hairline to the chin. Keep the eyes and mouth clear. If gestures matter, keep both hands fully in frame. Bringing the hands closer to waist or chest height gives you room for a closer shot.

Compare two starting images

Both examples use a 672 × 1280 frame.

Good · 7.14%. The full face is clear, with both arms and hands in frame.

Less suitable · 1.31%. The face is too small in this full-body shot.

3. Avoid solid-color backgrounds

Choose a background with some visible detail, such as a room, gym, or outdoor scene. A softly blurred setting works well if it still looks like a scene. Avoid flat studio colors, digital mattes, and green screens, even when the subject is illustrated or stylized.

Good background: The gym gives the scene visible detail without distracting from the subject.

Avoid: A flat blue background.

4. Add an image description when useful

source_images[].description is optional. Start with the shot size, then describe what the image shows, such as the subject’s clothing, pose, or any object they are holding.

Medium-long shot, framed from head to mid-thigh. A fitness instructor faces the camera in a black T-shirt, dark pants, and a headset. Both hands are visible at his sides. The background is a softly lit gym.

Add the image under avatars[0].visual.source_images when creating a session. This fragment shows only the image fields; see the Quickstart for a full request.

{
  "visual": {
    "source_images": [
      {
        "source_image_id": "portrait",
        "url": "https://YOUR_PUBLIC_HOST/portrait.jpg",
        "media_type": "image/jpeg",
        "description": "Medium-long shot, framed from head to mid-thigh. A fitness instructor faces the camera in a black T-shirt, dark pants, and a headset. Both hands are visible at his sides. The background is a softly lit gym."
      }
    ]
  }
}

Use a directly accessible image URL. The example includes description; adapt it to the image you use, or omit the field.

Overview

A1: Streaming Avatar

W1: Streaming World

Blazing Fast Video Generation

1. How Vivix frames your starting image

2. Keep the face clear

Compare two starting images

3. Avoid solid-color backgrounds

4. Add an image description when useful