fix: Add encrypted box on EC-3

[nick-michael]

Description

The fake encryption solution implemented for Xbox seems to be failing for streams that have EC-3 tracks so I've added an encryption box for that as well

Screenshots (optional)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• This change requires a documentation update

Checklist:

• I have signed the Google CLA https://cla.developers.google.com
• My code follows the style guidelines of this project
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have verified my change on multiple browsers on different platforms
• I have run ./build/all.py and the build passes
• I have run ./build/test.py and all tests pass

[avelad]

@nick-michael One question, doesn't the same thing happen with ac-3?

[nick-michael]

@nick-michael One question, doesn't the same thing happen with ac-3?

Probably, although I haven't got access to mixed (encrypted & unencrypted) content with AC3 audio tracks to test. I only noticed this while playing back on Xbox on a stream that has EC-3 and was able to verify that this fixed the problem. Happy to add a duplicate block for ac3 (would it be ac3 or ac-3?) as a preventative measure if you think it's a good idea.

I'm not sure how many other codecs are potentially available here to cause a problem.

[avelad]

@nick-michael , I've been looking, and the block should be ac-3.

I think it's a good idea to add it, but the expert is @joeyparrish

[nick-michael]

Ok no worries, I also reckon it makes sense to add it in but since I'm in no rush to get this merged on my side I'm happy to defer the decision

[shaka-bot]

All tests passed!