yt-dlp: Add mutagen variant

[TheRealKeto]

Description

Add mutagen variant to yt-dlp subport. This allows for mutagen to be used over AtomicParsley for metadata manipulation (e.g thumbnail embedding)

Closes: https://trac.macports.org/ticket/66945

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 12.6 21G115 arm64
Xcode 14.2 14C18

Verification

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[macportsbot]

Notifying maintainers:
@ryandesign for port youtube-dl.

[ryandesign]

All you've done here is add a dependency. You haven't told yt-dlp that it should use AtomicParsley or py-mutagen.

[ryandesign]

Also, you haven't removed the AtomicParsley dependency when the mutagen variant is used.

[TheRealKeto]

All you've done here is add a dependency. You haven't told yt-dlp that it should use AtomicParsley or py-mutagen.

yt-dlp automatically prioritizes mutagen and AtomicParsley, depending on which one is found first. Simply adding the dependency is sufficient.

Also, you haven't removed the AtomicParsley dependency when the mutagen variant is used.

I can't remove it even when removing it with depends_run-delete, as it's part of the ffmpeg default variant. Would it be acceptable to make two variants (e.g mutagen and atomic) within the yt-dlp subport? Alternatively, both dependencies can co-exist, as mutagen is mostly used to embed thumbnails.

[ryandesign]

All you've done here is add a dependency. You haven't told yt-dlp that it should use AtomicParsley or py-mutagen.

yt-dlp automatically prioritizes mutagen and AtomicParsley, depending on which one is found first. Simply adding the dependency is sufficient.

Yes, I'm sure that is what will happen but it is not sufficient for MacPorts. Consider the opposite situation: The user does not select the mutagen variant, but the user happens to have mutagen installed. The user expects yt-dlp to use AtomicParsley, but it uses mutagen, despite not declaring a dependency on it. We don't want that to happen.

Also, you haven't removed the AtomicParsley dependency when the mutagen variant is used.

I can't remove it even when removing it with depends_run-delete, as it's part of the ffmpeg default variant. Would it be acceptable to make two variants (e.g mutagen and atomic) within the yt-dlp subport? Alternatively, both dependencies can co-exist, as mutagen is mostly used to embed thumbnails.

I understand that simply adding depends_run-delete port:AtomicParsley within the variant will not accomplish the goal of removing the dependency; some restructuring of the port would be needed.

Yes, when there are two conflicting options, like AtomicParsley and mutagen, having two separate variants, which are marked as conflicting with one another and where the port enforces that one of the two variants must be selected and one of them is selected by default, is optimal in my opinion. It is complicated by the fact that yt-dlp is a subport of youtube-dl and youtube-dl presumably does not have the option of using mutagen.

What is the relationship between ffmpeg and AtomicParsley and mutagen? Currently the ffmpeg variant depends on both ffmpeg and AtomicParsley. Was that the right thing to do? Is the answer the same for youtube-dl and yt-dlp? Can ffmpeg be used without AtomicParsley? Can AtomicParsley be used without ffmpeg? Does mutagen use ffmpeg—mandatorily, optionally, or not at all? The answers to these questions might tell us whether we should have three variants, one for adding each dependency (and whatever mechanism might be needed to inform the software that it should or should not use that dependency), and which of them should requires the other.

The reason the ticket has remained unsolved for so many months is my lack of motivation to research the answers to these questions.

[TheRealKeto]

The hierarchy of dependencies which are of concern in this PR (AtomicParsley, mutagen, ffmpeg) is the following:

• yt-dlp prioritizes mutagen, but will use AtomicParsley if mutagen is not installed.
• If AtomicParsley and mutagen are missing, ffmpeg will be used.
• Neither project can't work without ffmpeg.

This can also be said about youtube-dl, although without mutagen in the mix. Given the concerns previously raised, I don't think this can be resolved.

Even if both youtube-dl and yt-dlp were to be separate port files, neither project has some kind of configuration system when building, making it impossible for either project to prioritize a dependency over another. As it stands, both projects have logic to detect and fallback on dependencies it's missing, but there's no way to enforce one dependency over another without heavy patching.