> For the complete documentation index, see [llms.txt](https://agpt.co/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://agpt.co/docs/integrations/block-integrations/concat.md).

# Video Concat

This block merges multiple video clips into a single continuous video, with optional transitions between clips.

## Video Concat

### What it is

Merge multiple video clips into one continuous video

### How it works

The block uses MoviePy's `concatenate_videoclips` function to join multiple videos in sequence. It supports three transition modes: **none** (direct concatenation), **crossfade** (smooth blending where clips overlap), and **fade\_black** (each clip fades out to black and the next fades in). At least 2 videos are required. The output is encoded with H.264 video codec and AAC audio codec.

### Inputs

| Input                | Description                                   | Type                                   | Required |
| -------------------- | --------------------------------------------- | -------------------------------------- | -------- |
| videos               | List of video files to concatenate (in order) | List\[str (file)]                      | Yes      |
| transition           | Transition between clips                      | "none" \| "crossfade" \| "fade\_black" | No       |
| transition\_duration | Transition duration in seconds                | int                                    | No       |
| output\_format       | Output format                                 | "mp4" \| "webm" \| "mkv" \| "mov"      | No       |

### Outputs

| Output          | Description                                | Type       |
| --------------- | ------------------------------------------ | ---------- |
| error           | Error message if the operation failed      | str        |
| video\_out      | Concatenated video file (path or data URI) | str (file) |
| total\_duration | Total duration in seconds                  | float      |

### Possible use case

* Combining multiple clips into a compilation video
* Assembling intro, main content, and outro segments
* Creating montages from multiple source videos
* Building video playlists or slideshows with transitions

***


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://agpt.co/docs/integrations/block-integrations/concat.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.