Add MatroskaJS Chapter Codec #835
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robUx4
added
format addition
spec_chapter_codec
Rather than reinventing the wheel with a custom language, we can reuse and well-known one. The goal of Matroska Script was to be similar to JavaScript/ECMAStrip/ActionScript. But, in JS, integers can only use 56 bits. So not all ChapterUID (64-bit unsigned integer) can be addressed with the current Matroska Script stable API. Rather than adding a different GotoAndPlay that is compatible with JavaScript (using a string), we start from scratch with ECMAScript 6th Edition (ES6).
This API is meant for interactive movies. The author adds choices in a chapter and retrieves the user choice at the end of this chapter. Depending on the choice, different actions can be performed. The choice rendering and user interaction is the responsibility of the player.
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Not sure it should go in the "historical" Chapter Codec document, ie make the specification for what existed so far. Or if it should be a document on its own. Maybe each command will need its own IANA registry. |
Labnann
reviewed
Sep 8, 2024
| ## MatroskaJS | ||
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| This is the case when `ChapProcessCodecID` = 2. This is a script language build for | ||
| Matroska purposes. It uses the [@!ECMAScript] 6th Edition (ES6) syntax. The commands are stored as text commands, in UTF-8. |
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That would be better (less constraint) but we don't have a working solution with that.
Also there are things that could make the JS usage cleaner like let and const or static arrays and typed arrays. For example you could have a global function that gets the list of choices in an array and call the MatroskaJS engine. Then each (enter) chapter would just had the array and that call.
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Rather than reinventing the wheel with a custom language, we can reuse and well-known one.
The goal of Matroska Script was to be similar to JavaScript/ECMAStrip/ActionScript.
But, in JavaScript, integers can only use 56 bits. So not all
ChapterUID(64-bit unsigned integer) can be addressedwith the current Matroska Script stable API, if an ECMAScript interpreter was used.
Rather than adding a different
GotoAndPlay()that is compatible with JavaScript (using a string), we start fromscratch with ECMAScript 6th Edition (ES6). We cannot handle the original
GotoAndPlay()with that engine anyway.The implementation of the Choice handling is almost complete in VLC by a Google Summer of Code student.
Fixes #658
Draft on top of #833