Add support for HLS/DASH content steering

[dchen-harmonicinc]

Initial requested under google/ExoPlayer#11203. Please advise the plan for the feature to be available under Media3.

Content steering is a new feature of both HLS and DASH standards, simplifying the design of multi-CDN systems, redundancy/failover functions, load balancing, and various other traffic optimization applications. A number of players (DASH.js, HLS.js, Apple's AVplayer, etc.) already support this feature.

The relevant specifications are:
[1] HLS Content Steering Specification (v1.2b1) https://developer.apple.com/streaming/HLSContentSteeringSpecification.pdf
[2] DASH-IF – https://www.etsi.org/deliver/etsi_ts/103900_103999/103998/01.01.01_60/ts_103998v010101p.pdf

The ask is: please add support for Content Steering functionality in Exoplayer.

Finer-level detail: if feasible, please include the _HLS/DASH_pathway and _HLS/DASH_throughput parameters in calls to the steering servers. These parameters help servers to react faster in cases of failures or other problems with CDNs.

[marcbaechinger]

Thanks for filing.

I assign to @tonihei like issue google/ExoPlayer#11203.. Usefulness of content steering for DASH/HLS is already acknowledged in that issue.

[tonihei]

Yes, this is a duplicate of google/ExoPlayer#11203, but I'll use the opportunity to move the issue over to the Media3 tracker and close the old one. We are still planning to implement HLS and DASH content steering.

[yreznik-brightcove]

FYI, a recent overview paper describing various features and benefits of this standard: https://www.ibc.org/technical-papers/ibc2024-tech-papers-content-steering-a-standard-for-multi-cdn-streaming/12072.article It also includes references to various existing implementations, streams, and tools that may be useful for testing.