encodingInfo() for "record" MediaEncodingType [1] is implemented in  https://crbug.com/709181 
For "transmission" type, it is tracked by https://crbug.com/817382.

However, current implementation does not take MediaEncodingConfiguration.MediaEncodingType into account, i.e. both type use the same code to respond encodingInfo().

Now encodingInfo() is marked as experimental [2]. I'm asking why.

[1] https://wicg.github.io/media-capabilities/#mediaencodingtype
[2]  https://crbug.com/824708 

Per email discussion with Chris:

The reason why MediaCapabilities.encodingInfo() is still in experimental is because it has not go through launch process [1].

The launch process starts with an origin trial, where top sites can opt in to expose the API and vet its claims of support and smoothness. MC.decodingInfo() cooperate with YouTube team to run experiments [2].

After we get result from origin trial, we can compose an "Intent to Ship" thread to ship the feature [3].


[1] https://www.chromium.org/blink/launching-features
[2] https://groups.google.com/a/chromium.org/forum/?utm_medium=email&utm_source=footer#!msg/blink-dev/dsdTLv33r4w/-SUKCfGkAwAJ
[3] https://groups.google.com/a/chromium.org/forum/?utm_medium=email&utm_source=footer#!msg/blink-dev/aXYvQ01tMhw/0nhgfJQsDQAJ