> For the complete documentation index, see [llms.txt](https://doc.duaer.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.duaer.com/build/duaer-video-concat.md).

# Join shots with Duaer Video Concat

In Duaer, Duaer Video Concat joins shots rendered by Duaer Video Render into one MP4, in item order. It is free.
## Join shots

1. Have Duaer Video Render output one item per shot. The item order is the shot order in the final video.
2. Connect Duaer Video Concat after it. Render ID defaults to {{ $json.renderId }}; you rarely need to change it.
3. Select Execute step. All input items become one output item: the binary field data holds the MP4, plus a new renderId, duration in seconds, and shots.

Join 2 to 40 shots at a time, all with the same shape. Shots can be joined for 3 hours after rendering, and joining waits at most 15 minutes.

## What Duaer Video Concat can join

Only renderIds returned by [Duaer Video Render](/build/duaer-video-render.md). Clips from Duaer Video have no renderId and cannot go straight into Duaer Video Concat.

The joined video has its own renderId, so you can pass it on to [Duaer Video Music](/build/duaer-video-music.md) for background music.
## Questions

### Why does Duaer Video Concat say it "needs at least 2 shots"?

Only one item came in. In Duaer, joining needs at least two Duaer Video Render shots, one item each.

### Why does Duaer Video Concat say "All shots must have the same shape"?

The shots mix landscape, portrait, or square. Render every shot with the same Resolution in Duaer Video Render, then join.

## Related

- [Render HTML to video with Duaer Video Render](https://doc.duaer.com/build/duaer-video-render.md)
- [Add background music with Duaer Video Music](https://doc.duaer.com/build/duaer-video-music.md)