Update av1.json

[DeeDeeG]

Addresses #4699 for now (although AV1 support in browsers is still under active development, so might update again soon.) I can't easily test the mobile browsers, or things like Baidu browser, etc, but this has all the updates for the "Big four" and Opera on desktop to the best of my knowledge.

Summary of changes:

• Opera 57+ now supports AV1 out-of-the-box [1]
• Firefox Beta and Release 63+ now support AV1, still off by default and behind a preference [2][3]
• Bitmovin demo is now usable with multiple browsers
  • (Because Chrome, Opera and Firefox all use AV1 1.0 now, and the Bitmovin demo also uses AV1 1.0 (I have to assume the support in Edge is AV1 1.0...))
  • In any case, I have personally tested the demo with Firefox and Chrome. It does work cross-browser.

[Eric-01]

Since you're working on it, I have a small request for you. Could you update the info about AV1 support in Firefox to include the changes in version 65.0 and later? In these versions the support for AV1 is enabled by default for Windows users (bug on Bugzilla).

My suggestion is to add note 3 with the following message: Enabled by default only for Windows users (or similar) next to the note 2 (example: "65":"n d #2" → "65":"n d #2 #3") in information about Firefox version 65.0 & 66.0. But it's just my suggestion, you can do what you want :)

[DeeDeeG]

I am not sure if they will keep it enabled in 65 past beta, but i guess we will see soon.

And unfortunately support details that fine can get complicated quickly. I'm not sure if any of the support mentioned in the data extends to Windows 32-bit yet, for example, since it has been not compiled for that platform for a while now. Hmmm.... So I'm not sure if it is worth that many notes. Maybe we should add the link to the tracking bug for Firefox to the links or notes section?

[DeeDeeG]

Here's the bug for Windows 32-bit support: https://bugzilla.mozilla.org/show_bug.cgi?id=1475564

[Eric-01]

You are probably right about the support on 32-bit Firefox on Windows. The appropriate bug is still open and I also checked whether the 32-bit Firefox Nightly (updated to the newest build) on 32-bit Windows 7 is able to decode AV1 (on the built-in default decoder and dav1d) or not. The result was expected – "not".

The best section for the info about support only on 64-bit Firefox on Windows would be "notes_by_num", since having max 3 notes next to version 65.0 or 66.0 is not too many, but on the other hand "notes" section also looks great for it. Link to the tracking bug (with text e.g. Firefox implementation bug) could go to the "links" section, I think.

[Fyrd]

Merging this as-is, any further changes can be added in new PRs. Thanks!