Add MSE support for FairPlay

[avelad]

I just discovered that Apple has updated all the FairPlay integration documentation including MSE example and how to use the api without prefixes (#2999).

Attached the relevant part in case someone does not have access:
FairPlay Streaming in Safari.zip

There are examples with key rotation, multi keys, etc.

[avelad]

Necessary changes:

• distinctiveIdentifier has to be not-allowed (I'll send a PR for it)
• persistentState has to be not-allowed (I'll send a PR for it)
• Persistent sessions are not allowed (I'll send a PR for it)
• For the renewal of keys the 'renew' event is listen, which right now is not in the ShakaPlayer code. @joeyparrish Do you have any idea how this should work?
• The contentType when MSE is not used should be 'application/vnd.apple.mpegurl' right now in the ShakaPlayer it gets 'video/mp4' by default (https://github.com/google/shaka-player/blob/master/lib/player.js#L2020) @joeyparrish Do you have any idea how this should work? Why is video/mp4 hardcoded?
• The integration of Media Capabilities should take all of this into account. @michellezhuogg

[valotvince]

I think Shaka should also provide a way for developers to be notified of which keySystem has been selected for playback, so that we could fetch/cache the appropriate certificate, and give it back as configuration (could have the same logic that the request/response filters).

[avelad]

I have seen Disney + uses HLS manifest with PlayReady, Widevine, and Fairplay using MSE. That would make us have greater efficiency in the CDN, since there would only be one copy (it would not be necessary to maintain DASH and HLS according to the device). @joeyparrish What is your opinion about this? What priority is this for the ShakaPlayer?

[joeyparrish]

I think Shaka should also provide a way for developers to be notified of which keySystem has been selected for playback

Do you mean in a specific event? Or just that you should be able to get it in general?

Today you can get this info with player.keySystem() at a few different times early on. You can do it after load() resolves or from the loaded event (roughly equivalent), or from the streaming event (which is earlier in the load process).

Would this suffice, or would you prefer a bespoke event?

@joeyparrish What is your opinion about this? What priority is this for the ShakaPlayer?

This is really exciting! I remember spending lots of fruitless hours trying to make MSE+FairPlay work, so it would be amazing to be able to enable it on desktop and MSE-enabled iOS devices.

I will defer to @ismena for priority, as she has taken over as the team lead.

[avelad]

I have been doing some testing and I have seen that MediaCapabitilies in Safari does not seem to support the encryption part, so with what is now in the repo it would not work.

I think it is related to shaka-project/eme-encryption-scheme-polyfill#18, @michellezhuogg , can you confirm it?

[valotvince]

@joeyparrish I think we should have a certificateURL key per advanced config DRM, Shaka would be responsible of fetching the certificate (if serverCertificate is NOT provided), allowing developers to catch the event through a request / response filter, and then do our own logic (cache the certificate in my own use case, to give it back as serverCertificate for the next load).

That's a thing we already do with the Widevine certificate even if it is not the same exact use case, since we have two license requests triggered by the CDM (the first one to fetch the certificate, the second to fetch the license).

[avelad]

@valotvince Maybe #1906 ?

[valotvince]

@avelad Totally !