# Convert videos to HLS, MPEG-Dash and CMAF
š¤/video/adaptive encodes videos into HTTP Live Streaming (HLS), MPEG-Dash and CMAF supported formats and generates the necessary manifest and playlist files.
This Robot accepts all types of video files and audio files. Do not forget to use Step bundling in your `use` parameter to make the Robot work on several input files at once.
This Robot is normally used in combination with [š¤/video/encode](/docs/robots/video-encode.md). We have implemented video and audio encoding presets specifically for MPEG-Dash and HTTP Live Streaming support. These presets are prefixed with `"dash/"` and `"hls/"`. [View a HTTP Live Streaming demo here](/demos/video-encoding/implement-http-live-streaming.md).
### Required CORS settings for MPEG-Dash and HTTP Live Streaming
Playing back MPEG-Dash Manifest or HLS playlist files requires a proper CORS setup on the server-side. The file-serving server should be configured to add the following header fields to responses:
```
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET
Access-Control-Allow-Headers: *
```
If the files are stored in an Amazon S3 Bucket, you can use the following [CORS definitionā ](https://docs.aws.amazon.com/AmazonS3/latest/userguide/ManageCorsUsing.html) to ensure the CORS header fields are set correctly:
```json
[
{
"AllowedHeaders": ["*"],
"AllowedMethods": ["GET"],
"AllowedOrigins": ["*"],
"ExposeHeaders": []
}
]
```
To set up CORS for your S3 bucket:
1. Visit [https://s3.console.aws.amazon.com/s3/buckets/ā ](https://s3.console.aws.amazon.com/s3/buckets/)
2. Click on your bucket
3. Click "Permissions"
4. Edit "Cross-origin resource sharing (CORS)"
### Storing Segments and Playlist files
The Robot gives its result files (segments, initialization segments, MPD manifest files and M3U8 playlist files) the right metadata property `relative_path`, so that you can store them easily using one of our storage Robots.
In the `path` parameter of the storage Robot of your choice, use the Assembly Variable `${file.meta.relative_path}` to store files in the proper paths to make the playlist files work.
## Usage example
Implementing HTTP Live Streaming: encode the uploaded video into three versions, then cut them into several segments and generate playlist files containing all the segments:
```
{
"steps": {
":original": {
"robot": "/upload/handle"
},
"encoded_480p": {
"robot": "/video/encode",
"use": ":original",
"preset": "hls/480p",
"ffmpeg_stack": "v7"
},
"encoded_720p": {
"robot": "/video/encode",
"use": ":original",
"preset": "hls/720p",
"ffmpeg_stack": "v7"
},
"encoded_1080p": {
"robot": "/video/encode",
"use": ":original",
"preset": "hls/1080p",
"ffmpeg_stack": "v7"
},
"hls_bundled": {
"robot": "/video/adaptive",
"use": {
"steps": [
"encoded_480p",
"encoded_720p",
"encoded_1080p"
],
"bundle_steps": true
},
"technique": "hls",
"playlist_name": "my_playlist.m3u8"
}
}
}
```
## Parameters
*
### `interpolate`
`boolean | Record`\
Controls whether Assembly Variables are interpolated for individual instruction fields.\
By default, most Robot instruction fields interpolate Assembly Variables. Set this to `false` to treat every instruction field as literal text, or set an individual field path to `false` to treat only that field as literal text. For Robot-specific fields that are literal by default, set this to `true` or set that field path to `true` to opt back into interpolation.\
Use field names such as `path`, or dotted paths such as `ffmpeg.vf` for nested objects.
*
### `output_meta`
`Record | boolean | Array`\
Allows you to specify a set of metadata that is more expensive on CPU power to calculate, and thus is disabled by default to keep your Assemblies processing fast.\
For images, you can add `"has_transparency": true` in this object to extract if the image contains transparent parts and `"dominant_colors": true` to extract an array of hexadecimal color codes from the image.\
For images, you can also add `"blurhash": true` to extract a [BlurHashā ](https://blurha.sh) string ā a compact representation of a placeholder for the image, useful for showing a blurred preview while the full image loads.\
For videos, you can add the `"colorspace": true` parameter to extract the colorspace of the output video.\
For videos, you can also add `"interlaced": true` to detect whether the video is interlaced. This combines the cheap ffprobe `field_order` flag with a bounded `idet` sampling pass over the first frames of the source, exposing `interlaced`, `field_order`, and a diagnostic `interlace_detection` object under `file.meta`. This is computationally expensive and billed accordingly.\
For audio, you can add `"mean_volume": true` to get a single value representing the mean average volume of the audio file.\
You can also set this to `false` to skip metadata extraction and speed up transcoding.
*
### `user_meta`
`Record`(default: `{}`)\
Adds custom metadata to each file emitted by this Robot without modifying the fileās contents.\
The values are merged with any existing `user_meta` carried by the input file. If both objects contain the same key, this Robotās value takes precedence. Assembly Variables are supported, for example `{ "internal_file_id": "${file.id}" }`.
*
### `result`
`boolean`(default: `false`)\
Whether the results of this Step should be present in the Assembly Status JSON
*
### `queue`
`batch`\
Setting the queue to 'batch', manually downgrades the priority of jobs for this step to avoid consuming Priority job slots for jobs that don't need zero queue waiting times
*
### `force_accept`
`boolean`(default: `false`)\
Force a Robot to accept a file type it would have ignored.\
By default, Robots ignore files they are not familiar with.[š¤/video/encode](/docs/robots/video-encode.md), for example, will happily ignore input images.\
With the `force_accept` parameter set to `true`, you can force Robots to accept all files thrown at them. This will typically lead to errors and should only be used for debugging or combatting edge cases.
*
### `ignore_errors`
`boolean | Array`(default: `[]`)\
Ignore errors during specific phases of processing.\
Setting this to `["meta"]` will cause the Robot to ignore errors during metadata extraction.\
Setting this to `["execute"]` will cause the Robot to ignore errors during the main execution phase.\
Setting this to `true` is equivalent to `["meta", "execute"]` and will ignore errors in both phases.
*
### `use`
`string | Array | Array