MediaTailor parameter session behavior and persistence

AWS Elemental MediaTailor processes parameters at session initialization and maintains them throughout the session lifecycle. Understanding session behavior is crucial for implementing dynamic parameter scenarios.

Session initialization methods

MediaTailor supports multiple methods for session initialization with parameters:

1. Implicit session initialization: Parameters included in the initial manifest request

   GET /v1/master/123456789/originId/index.m3u8?manifest.auth_token=abc123&start=2024-08-26T10:00:00Z

2. Explicit session initialization (POST): Parameters provided in the request body

   POST /v1/session/123456789/originId/index.m3u8
   {
       "adsParams": {"param1": "value1"},
       "manifestParams": {"auth_token": "abc123"}
   }

3. Explicit session initialization (GET): Parameters provided as query parameters

   GET /v1/session/123456789/originId/index.m3u8?ads.param1=value1&manifestParams.auth_token=abc123

Parameter persistence and immutability

MediaTailor parameter behavior follows these rules:

• One-time specification: Parameters can only be specified once, at session initialization

• Session-wide persistence: Parameters are maintained throughout the entire session

• Immutable after initialization: Parameters cannot be modified after the session is created

• Configuration alias resolution: Aliases are resolved to actual values before forwarding to destinations

Parameter modification scenarios

To modify parameters during playback:

• Create new session: Initialize a new session with updated parameter values

• Player transition: Seamlessly transition the player to the new session

• Parameter inheritance: Carry forward unchanged parameters to maintain consistency

Example Modifying time-shift parameters

To change from a 1-hour window to a 2-hour window:

1. Current session: start=2024-08-26T10:00:00Z&end=2024-08-26T11:00:00Z

2. Create new session: start=2024-08-26T10:00:00Z&end=2024-08-26T12:00:00Z

3. Transition player to new session URL

Important

Multiple multivariant playlist requests for a single session do not update parameters after the first request. Parameters remain immutable for the session duration.