Configure an AWS Elemental MediaLive channel class (STANDARD vs SINGLE_PIPELINE) with automatic input failover

Steps

1. Choose the channel class at channel creation: `STANDARD` gives the channel two pipelines with two input entry points (identical output delivered to two destinations per output); `SINGLE_PIPELINE` gives the channel exactly one pipeline and one destination per output.
2. If using SINGLE_PIPELINE, optionally configure 'linked channels' for pipeline locking: designate one channel as Primary (owns the linked group) and one as Follower (references the primary channel's ARN) — only one follower may link to a given primary, and both must be in the same AWS account.
3. To add automatic input failover (AIF), create two push-type inputs of the identical input type (e.g. both RTMP) carrying identical content, then attach both to the channel and configure them as a failover pair.
4. AIF only works with push inputs — pull inputs cannot be used, and MediaLive supports only one Elemental Link input per channel, so a Link input can't be part of a failover pair.
5. Configure failure-detection conditions on the failover pair: input loss (no content for a specified period), black video, and/or audio silence — MediaLive switches to the other input when a configured condition is detected.
6. For maximum resiliency, combine AIF with a STANDARD (two-pipeline) channel — this requires four total upstream source streams (two inputs x two pipelines).