# Concatenate video files

Transloadit allows you to concatenate multiple videos together. This is useful when you want to add an introduction or an advertisement to the beginning or end of a video.

With the increased use of ad-blockers pressing on revenue of publishers, server-side ad insertion is a good way to make sure ads aren't blocked.

In this particular demo, you can upload the original, and we will "pre-roll" a clip that we import over HTTP. Videos are concatenated in the order of the `as` property in the `use` parameter. For example, `as: "video_1"` will be prepended to `as: "video_2"`.

If you have a Step that produces multiple files, they are sorted and concatenated in that order.

All sorting is done via a natural sorting algorithm (so `1` goes before `10`, which is not always the case in other sorting algorithms).

Step 1

### Handle uploads

We can handle uploads of your users directly. [Learn more ›](/services/handling-uploads.md)

[surf.mp4](https://demos.transloadit.com/15/641aedf2d24ccebd1539705c6071a3/surf.mp4)

Video · 32 MB · 22s · 1280 × 720

```
":original": {
  "robot": "/upload/handle"
}
```

🤖 [/upload/handle](/docs/robots/upload-handle.md)

This bot receives uploads that your users throw at you from browser or apps, or that you throw at us programmatically

Step 2

### Import files from web servers

We are happy to import from whatever storage solution suits you best. [Learn more ›](/services/file-importing.md)

[waves10.mp4](https://demos.transloadit.com/d7/98d168438b411eaac8cd9f0ee58efe/waves10.mp4)

Video · 1.9 MB · 13s · 1024 × 768

```
"preroll_imported": {
  "robot": "/http/import",
  "result": true,
  "url": "https://demos.transloadit.com/inputs/waves10.mp4"
}
```

🤖 [/http/import](/docs/robots/http-import.md)

This bot imports any file that is publicly available via a web URL into Transloadit

Step 3

### Transcode, resize, or watermark videos

We offer a variety of video encoding features like optimizing for different devices, merging, injecting ads, changing audio tracks, or adding company logos. [Learn more ›](/services/video-encoding.md)

[waves10.mp4](https://demos.transloadit.com/37/5f1499b0d74a8f9fa13fdb80148f61/waves10.mp4)

Video · 2.0 MB · 13s · 480 × 270

```
"preroll_resized": {
  "use": "preroll_imported",
  "robot": "/video/encode",
  "result": true,
  "background": "#00000000",
  "ffmpeg_stack": "v7",
  "height": 270,
  "preset": "ipad-high",
  "resize_strategy": "pad",
  "turbo": true,
  "width": 480
}
```

🤖 [/video/encode](/docs/robots/video-encode.md)

This bot encodes, resizes, applies watermarks to videos and animated GIFs

Step 4

### Transcode, resize, or watermark videos

We offer a variety of video encoding features like optimizing for different devices, merging, injecting ads, changing audio tracks, or adding company logos. [Learn more ›](/services/video-encoding.md)

[surf.mp4](https://demos.transloadit.com/eb/656ecbdce34d179c785ef24f02e415/surf.mp4)

Video · 3.6 MB · 22s · 480 × 270

```
"original_resized": {
  "use": ":original",
  "robot": "/video/encode",
  "result": true,
  "background": "#00000000",
  "ffmpeg_stack": "v7",
  "height": 270,
  "preset": "ipad-high",
  "resize_strategy": "pad",
  "turbo": true,
  "width": 480
}
```

🤖 [/video/encode](/docs/robots/video-encode.md)

This bot encodes, resizes, applies watermarks to videos and animated GIFs

Step 5

### Concatenate videos

We offer a variety of video encoding features like optimizing for different devices, merging, injecting ads, changing audio tracks, or adding company logos. [Learn more ›](/services/video-encoding.md)

[surf\_waves10.mp4](https://demos.transloadit.com/c1/2da76cda454bdaa7145ef2016acee5/surf%5Fwaves10.mp4)

Video · 5.0 MB · 34s · 1024 × 768

```
"concatenated": {
  "use": {
    "steps": [
      {
        "name": "original_resized",
        "as": "video_1"
      },
      {
        "name": "preroll_resized",
        "as": "video_2"
      }
    ]
  },
  "robot": "/video/concat",
  "result": true,
  "ffmpeg_stack": "v7",
  "preset": "ipad-high"
}
```

🤖 [/video/concat](/docs/robots/video-concat.md)

This bot concatenates several videos together

Step 6

### Export files to Amazon S3

We export to the storage platform of your choice. [Learn more ›](/services/file-exporting.md)

`:original`

* [https://demos.transloadit.com/15/641aedf2d24ccebd1539705c6071a3/surf.mp4⁠](https://demos.transloadit.com/15/641aedf2d24ccebd1539705c6071a3/surf.mp4)

`preroll_imported`

* [https://demos.transloadit.com/d7/98d168438b411eaac8cd9f0ee58efe/waves10.mp4⁠](https://demos.transloadit.com/d7/98d168438b411eaac8cd9f0ee58efe/waves10.mp4)

`preroll_resized`

* [https://demos.transloadit.com/37/5f1499b0d74a8f9fa13fdb80148f61/waves10.mp4⁠](https://demos.transloadit.com/37/5f1499b0d74a8f9fa13fdb80148f61/waves10.mp4)

`original_resized`

* [https://demos.transloadit.com/eb/656ecbdce34d179c785ef24f02e415/surf.mp4⁠](https://demos.transloadit.com/eb/656ecbdce34d179c785ef24f02e415/surf.mp4)

`concatenated`

* [https://demos.transloadit.com/c1/2da76cda454bdaa7145ef2016acee5/surf\_waves10.mp4⁠](https://demos.transloadit.com/c1/2da76cda454bdaa7145ef2016acee5/surf%5Fwaves10.mp4)

```
"exported": {
  "use": [
    "preroll_imported",
    "preroll_resized",
    "original_resized",
    "concatenated",
    ":original"
  ],
  "robot": "/s3/store",
  "credentials": "demo_s3_credentials",
  "url_prefix": "https://demos.transloadit.com/"
}
```

🤖 [/s3/store](/docs/robots/s3-store.md)

This bot exports encoding results to Amazon S3

## Live Demo. See for yourself

Loading Uppy demo…

This live demo is powered by [Uppy⁠](https://uppy.io/docs/guides/uppy-transloadit/), our open source file uploader that you can also use without Transloadit, and [tus⁠](https://tus.io), our open protocol for resumable file uploads that is making uploading more reliable across the world.

## Build this in your own language

```
<!-- This pulls Uppy from our CDN -->
<!-- For smaller self-hosted bundles, install Uppy and plugins manually: -->
<!-- npm i --save @uppy/core @uppy/dashboard @uppy/remote-sources @uppy/transloadit ... -->
<link
  href="https://releases.transloadit.com/uppy/v3.10.0/uppy.min.css"
  rel="stylesheet"
/>
<button id="browse">Select Files</button>
<script type="module">
  import {
    Uppy,
    Dashboard,
    ImageEditor,
    RemoteSources,
    Transloadit,
  } from 'https://releases.transloadit.com/uppy/v3.10.0/uppy.min.mjs'
  const uppy = new Uppy()
    .use(Transloadit, {
      waitForEncoding: true,
      alwaysRunAssembly: true,
      assemblyOptions: {
        params: {
          // It's often better store encoding instructions in your account
          // and use a `template_id` instead of adding these steps inline
          steps: {
            ':original': {
              robot: '/upload/handle',
            },
            preroll_imported: {
              robot: '/http/import',
              result: true,
              url: 'https://demos.transloadit.com/inputs/waves10.mp4',
            },
            preroll_resized: {
              use: 'preroll_imported',
              robot: '/video/encode',
              result: true,
              background: '#00000000',
              ffmpeg_stack: 'v7',
              height: 270,
              preset: 'ipad-high',
              resize_strategy: 'pad',
              turbo: true,
              width: 480,
            },
            original_resized: {
              use: ':original',
              robot: '/video/encode',
              result: true,
              background: '#00000000',
              ffmpeg_stack: 'v7',
              height: 270,
              preset: 'ipad-high',
              resize_strategy: 'pad',
              turbo: true,
              width: 480,
            },
            concatenated: {
              use: {
                steps: [
                  {
                    name: 'original_resized',
                    as: 'video_1',
                  },
                  {
                    name: 'preroll_resized',
                    as: 'video_2',
                  },
                ],
              },
              robot: '/video/concat',
              result: true,
              ffmpeg_stack: 'v7',
              preset: 'ipad-high',
            },
            exported: {
              use: ['preroll_imported', 'preroll_resized', 'original_resized', 'concatenated', ':original'],
              robot: '/s3/store',
              credentials: 'demo_s3_credentials',
              url_prefix: 'https://demos.transloadit.com/',
            },
          },
        },
      },
    })
    .use(Dashboard, { trigger: '#browse' })
    .use(ImageEditor, { target: Dashboard })
    .use(RemoteSources, {
      companionUrl: 'https://api2.transloadit.com/companion',
    })
    .on('complete', ({ transloadit }) => {
      // Due to `waitForEncoding:true` this is fired after encoding is done.
      // Alternatively, set `waitForEncoding` to `false` and provide a `notify_url`
      console.log(transloadit) // Array of Assembly Statuses
      for (const assembly of transloadit) {
        console.log(assembly.results) // Array of all encoding results
      }
    })
    .on('error', (error) => {
      console.error(error)
    })
</script>

```

[Read docs: Browsers](/docs/sdks/uppy.md)

## So many ways to integrate

Transloadit is a service for companies with developers. And there are many ways developers can put Transloadit to good use inside your company to automate media processing.

#### Bulk imports

Add one of our [import Robots](/services/file-importing.md) to acquire and transcode massive media libraries.

#### Handling uploads

We are *the* experts at reliably [handling uploads](/services/handling-uploads.md). We wrote the [protocol⁠](https://tus.io/) for it.

#### Front-end integration

We integrate with web browsers via our next-gen file uploader [Uppy⁠](https://uppy.io/docs/guides/uppy-transloadit/) and SDKs for Android and iOS.

#### Back-end integration

Send us batch jobs in any server language using one of our [SDKs](/docs/sdks.md) or directly interfacing with our [REST API](/docs/api.md).

#### Pingbacks

Configure a [notify\_url](/services/content-delivery.md) to let your server receive transcoding results JSON in the `transloadit` POST field.

#### On-demand

Use our [Smart CDN](/services/file-importing.md) to adapt files on-demand and stream them directly to your users.

[Browsers](/docs/sdks/uppy.md)[TransloaditKit](/docs/sdks/transloaditkit.md)[Ruby SDK](/docs/sdks/ruby-sdk.md)[HTTP REST API](/docs/api.md)[Python SDK](/docs/sdks/python-sdk.md)[PHP SDK](/docs/sdks/php-sdk.md)[Node.js SDK](/docs/sdks/node-sdk.md)[Java SDK](/docs/sdks/java-sdk.md)[Go SDK](/docs/sdks/go-sdk.md)[cURL](/docs/sdks/curl.md)[Convex](/docs/sdks/convex.md)

[Browsers](/docs/sdks/uppy.md)[TransloaditKit](/docs/sdks/transloaditkit.md)[Ruby SDK](/docs/sdks/ruby-sdk.md)[HTTP REST API](/docs/api.md)[Python SDK](/docs/sdks/python-sdk.md)[PHP SDK](/docs/sdks/php-sdk.md)[Node.js SDK](/docs/sdks/node-sdk.md)[Java SDK](/docs/sdks/java-sdk.md)[Go SDK](/docs/sdks/go-sdk.md)[cURL](/docs/sdks/curl.md)[Convex](/docs/sdks/convex.md)

[Browsers](/docs/sdks/uppy.md)[TransloaditKit](/docs/sdks/transloaditkit.md)[Ruby SDK](/docs/sdks/ruby-sdk.md)[HTTP REST API](/docs/api.md)[Python SDK](/docs/sdks/python-sdk.md)[PHP SDK](/docs/sdks/php-sdk.md)[Node.js SDK](/docs/sdks/node-sdk.md)[Java SDK](/docs/sdks/java-sdk.md)[Go SDK](/docs/sdks/go-sdk.md)[cURL](/docs/sdks/curl.md)[Convex](/docs/sdks/convex.md)

## Other cool demos

* [View demo→Video EncodingAdd an audio track to video footage](/demos/video-encoding/add-audio-track-to-video-footage.md)
* [View demo→Video EncodingAdd an empty audio track to still video](/demos/video-encoding/add-empty-audio-track-to-still-video.md)
* [View demo→Document ProcessingAdd a header or footer to a PDF](/demos/document-processing/add-header-or-footer-to-pdf.md)

Try Transloadit

## Ready to get started?

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