This is version 2.18 of the AWS Elemental Server documentation. This is the latest version. For prior versions, see the *Previous Versions* section of [AWS Elemental Conductor File and AWS Elemental Server Documentation](https://docs.aws.amazon.com/elemental-server/).

# Getting Ready to Create HLS Rendition Groups
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## Step 1. Create a Mapping
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Identify the video, audio, audio rendition groups and captions you require. Review the [Rules for Rendition Groups](hls-rendition-groups-rules.md) to ensure you design an output that is valid. For example:
+ Video “high definition.”
+ Video “low definition.”
+ A rendition group named “AAC group” for AAC audio.
+ A rendition group named “Dolby group” for Dolby Digital audio.
+ Audio English AAC in “AAC group” rendition group.
+ Audio English Dolby Digital in “Dolby group” rendition group.
+ Audio French AAC in “AAC group” rendition group.
+ Audio French Dolby Digital in “Dolby group” rendition group.
+ Video “high definition” to be associated with both rendition groups.
+ Video “low definition” to be associated with the “Dolby group” rendition group.
+ Captions in English and French in WebVTT format, to be associated with both rendition groups.

![This illustration shows an example output group.](http://docs.aws.amazon.com/elemental-server/latest/ug/images/hls-rendition-groups-getting-ready-create-mapping.png)


## Step 2. Determine Defaults and Auto-Selection Behavior
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For each audio rendition group, decide which audio will be the default and how auto-selection works for the non-defaults. Setting up this information is useful if:
+ The user has specified an audio preference on the client player but that preference is not available, or
+ If the user has not specified an audio preference. 

(Obviously, if the user has specified a preference and that preference is available, the client player will select that preference.)

## Determine Defaults and Auto-Selection Behavior Up to Version 2.9.x
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Set the **Alternate Audio Track Selection** field. The options for this field for each audio stream are: 
+ **Default Audio**: The client player *should* select this stream. Only one stream in the rendition group should be set as the default; otherwise, the client player may behave unexpectedly. 
+ **Alternate Audio, Auto Select**: The client player *may * select this stream. Any number of streams in the rendition group can be set this way. The client player typically selects a stream based on the chosen system language or some other rule.
+ **Alternate Audio, not Auto Select**: The client player *should never * select this stream. Any number of streams in the rendition group can be set this way.

Set the **Alternate Audio Track Selection ** as follows. 


| Desired Result | How to Set | 
| --- | --- | 
| There is a default. The player can auto-select any of the other audios. |  [See the AWS documentation website for more details](http://docs.aws.amazon.com/elemental-server/latest/ug/hls-rendition-groups-getting-ready-to-create.html)  | 
| There is a default. The player cannot auto-select any of the other audios. |  [See the AWS documentation website for more details](http://docs.aws.amazon.com/elemental-server/latest/ug/hls-rendition-groups-getting-ready-to-create.html)  | 
| There is a default. There are specific audios that the player can auto-select. |  [See the AWS documentation website for more details](http://docs.aws.amazon.com/elemental-server/latest/ug/hls-rendition-groups-getting-ready-to-create.html)  | 
| There is no default. The player can auto-select any audio it chooses. |  [See the AWS documentation website for more details](http://docs.aws.amazon.com/elemental-server/latest/ug/hls-rendition-groups-getting-ready-to-create.html)  | 
| There is no default. The player cannot auto-select any audio. |  [See the AWS documentation website for more details](http://docs.aws.amazon.com/elemental-server/latest/ug/hls-rendition-groups-getting-ready-to-create.html)  | 
| There is no default. There are specific audios that the player can auto-select. |  [See the AWS documentation website for more details](http://docs.aws.amazon.com/elemental-server/latest/ug/hls-rendition-groups-getting-ready-to-create.html)  | 

## Determine Defaults and Auto-Selection Behavior
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Set the Audio Track Type field. The options for this field for each audio stream follow. 


| Value | Client Player Behavior | Representation in HLS Manifest | 
| --- | --- | --- | 
| Alternate Audio, Auto Select, Default | The client player should select this stream. Only one stream in the rendition group should be set as the default; otherwise, the client player may behave unexpectedly. | EXT-X-MEDIA with DEFAULT=YES, AUTOSELECT=YES | 
| Alternate Audio, Auto Select, Not Default | The client player may select this stream. Any number of streams in the rendition group can be set this way. | EXT-X-MEDIA with DEFAULT=NO, AUTOSELECT=YES | 
| Alternate Audio, not Auto Select | The client player should never select this stream. Any number of streams in the rendition group can be set this way. | EXT-X-MEDIA with DEFAULT=NO, AUTOSELECT=NO | 
| Audio-Only Variant Stream | The client can play back this audio-only stream instead of video in low-bandwidth scenarios. | EXT-X-STREAM-INF | 

1. Set the **Alternate Audio Track Selection** as follows:    
[See the AWS documentation website for more details](http://docs.aws.amazon.com/elemental-server/latest/ug/hls-rendition-groups-getting-ready-to-create.html)

1. In addition, if you have an audio that is intended as the audio to play when the bandwidth is so low that the video cannot be delivered, then set that audio to “**Audio-Only Variant Stream**.”