> ## Documentation Index
> Fetch the complete documentation index at: https://docs.comfy.org/llms.txt
> Use this file to discover all available pages before exploring further.

# SAM3_TrackPreview - ComfyUI Built-in Node Documentation

> Complete documentation for the SAM3_TrackPreview node in ComfyUI. Learn its inputs, outputs, parameters and usage.

> This documentation was AI-generated. If you find any errors or have suggestions for improvement, please feel free to contribute! [Edit on GitHub](https://github.com/Comfy-Org/embedded-docs/blob/main/comfyui_embedded_docs/docs/SAM3_TrackPreview/en.md)

## Overview

This node creates a video preview of tracked objects, drawing each tracked object with a distinct color overlay and a number label. It does not output any image or video tensors — instead, it saves the resulting preview video directly to a temporary file.

## Inputs

| Parameter    | Data Type   | Required | Range                    | Description                                                                                                  |
| ------------ | ----------- | -------- | ------------------------ | ------------------------------------------------------------------------------------------------------------ |
| `track_data` | TRACK\_DATA | Yes      | -                        | The tracking data containing packed masks and object information from a SAM3 tracking node.                  |
| `images`     | IMAGE       | No       | -                        | Optional input images to use as the background for the preview. If not provided, a black background is used. |
| `opacity`    | FLOAT       | No       | 0.0 to 1.0 (step: 0.05)  | The opacity of the color overlay applied to tracked objects (default: 0.5).                                  |
| `fps`        | FLOAT       | No       | 1.0 to 120.0 (step: 1.0) | The frame rate of the output video (default: 24.0).                                                          |

## Outputs

| Output Name | Data Type      | Description                                                                         |
| ----------- | -------------- | ----------------------------------------------------------------------------------- |
| `ui`        | PREVIEW\_VIDEO | A UI element that displays the generated preview video. No tensor data is returned. |

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