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

# coreav join

> Join MP4 or MOV files that share a codec configuration into one MP4, without re-encoding.

`coreav join -o OUTPUT INPUTS...` joins MP4 or MOV files, in the order given, into one MP4 file by stream copy. The inputs must share a codec configuration, as the parts of one recording do. The summary is [`coreav.join/1`](https://github.com/coreav-dev/coreav/blob/main/docs/schema/join-v1.md).

## Example

```sh theme={null}
coreav join -o joined.mp4 part-0.mp4 part-1.mp4 part-2.mp4
```

The same join is available as `coreav ffmpeg -f concat` ([`coreav ffmpeg`](/docs/commands/ffmpeg)).

## Options

```text theme={null}
Join MP4/MOV files that share a codec configuration into one MP4, without re-encoding

Usage: coreav join [OPTIONS] --output <OUTPUT> <INPUTS>...

Arguments:
  <INPUTS>...  The files to join, in order

Options:
  -o, --output <OUTPUT>  Where to write the joined file: a new file, or `-` for standard output
      --audio <none>     `none` to join the video only (default: the first audio stream of every input)
      --allow <CODEC>    Codecs to accept, comma separated, as for `coreav probe`
      --strict           Reject an input when a stream's codec is not allowed
      --force            Overwrite OUTPUT if it exists
  -h, --help             Print help
```


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