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.
Getting Ready to Create HLS Rendition Groups
Step 1. Create a Mapping
Identify the video, audio, audio rendition groups and captions you require. Review the Rules for Rendition Groups to ensure you design an output that is valid. For example:
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Video “high definition.”
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Video “low definition.”
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A rendition group named “AAC group” for AAC audio.
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A rendition group named “Dolby group” for Dolby Digital audio.
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Audio English AAC in “AAC group” rendition group.
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Audio English Dolby Digital in “Dolby group” rendition group.
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Audio French AAC in “AAC group” rendition group.
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Audio French Dolby Digital in “Dolby group” rendition group.
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Video “high definition” to be associated with both rendition groups.
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Video “low definition” to be associated with the “Dolby group” rendition group.
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Captions in English and French in WebVTT format, to be associated with both rendition groups.
Step 2. Determine Defaults and Auto-Selection Behavior
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:
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The user has specified an audio preference on the client player but that preference is not available, or
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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.)
Set the Alternate Audio Track Selection field. The options for this field for each audio stream are:
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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.
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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.
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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. |
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| There is a default. The player cannot auto-select any of the other audios. |
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| There is a default. There are specific audios that the player can auto-select. |
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| There is no default. The player can auto-select any audio it chooses. |
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| There is no default. The player cannot auto-select any audio. |
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| There is no default. There are specific audios that the player can auto-select. |
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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 |
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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. -
Set only one audio stream to “Alternate Audio, Auto-Select, Not Default, Default.”
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Set every other audio stream to “Alternate Audio, Auto-Select, Not Default.”
There is a default. The player cannot auto-select any of the other audios. -
Set only one audio stream to “Alternate Audio, Auto-Select, Not Default, Default.”
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Set every other audio stream to “Alternate Audio, not Auto-Select.”
There is a default. There are specific audios that the player can auto-select. -
Set only one audio stream to “Alternate Audio, Auto-Select, Not Default, Default.”
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Set some of the other audio streams to “Alternate Audio, Auto-Select, Not Default.”
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Set some of the other audio streams to “Alternate Audio, not Auto Select.”
There is no default. The player can auto-select any audio it chooses. -
Set every audio stream to “Alternate Audio, Auto-Select, Not Default.”
There is no default. The player cannot auto-select any audio. -
Set every audio stream to “Alternate Audio, not Auto-Select.”
There is no default. There are specific audios that the player can auto-select. -
Set some audio streams to “Alternate Audio, Auto-Select, Not Default.”
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Set some audio streams to “Alternate Audio, not Auto-Select.”
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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.”
