[youtube] Use localized title & channel name

[mjsir911]

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What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
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Description of your pull request and other information

Get the localized version of title, channel name

• Prioritize microformat title & description over basic title & description
• Fix bug causing channel to never be set, expecting wrong type

Related:

• [youtube] Extract original title from channel and playlist #27371
• Support translated titles (youtube) #13811 Related, alternative feedback. Embed original title somewhere?

Fixes:

• Fixes [YouTube] Support Getting Original Titles for Videos That Have Translated Titles #28421
• Fixes youtube language selection for video title/description #27738
• Fixes Downloading Youtube playlist containing translated title results in inconsistent title. #27499
• Fixes Please add workaround for forced YouTube translated video titles #10758
• Fixes Youtube channel not extract original title #27075 (why is this closed?)
• Fixes Youtube translated title's dont stick mpv-player/mpv#8676

This codebase was a pleasure to work with, kudos

[mjsir911]

Also closes #28562 but the same fix done in this PR was implemented in 49fc0a5 :)

This PR adds tests for it too though

[theultramage]

If you don't mind, could you explain what your edit does, what the logic behind it is, and in what way does it successfully resolve the issues you are intending to close? At first glance it is hard to tell from just the code change, because the diff is tiny and just changes the order of operations. I am worried that your 'localized version' actually means 'the hardcoded en-US version'. At least two of the issues you referenced are requesting control over the selected language. One is asking for additional commandline switches for retrieving the title/desc in one, multiple or all available languages, like how it's currently done for subtitles. I don't believe this PR addresses these, and may even be working against the goals of those issue reports.

[mjsir911]

I appreciate the feedback @theultramage!

could you explain what your edit does, what the logic behind it is, and in what way does it successfully resolve the issues you are intending to close?

Currently, youtube's video_details.get('title') returns the canonical title of a video, while microformat.get('title') returns the version specified by the uploader localized to the request's language, if available.

Example:

$ youtube-dl --get-title https://www.youtube.com/watch?v=UnIhRpIT7nc --print-traffic # returns english translated
... Accept-Language: en-us,en ...
inabakumori - Lagtrain (Vo. Kaai Yuki) / 稲葉曇『ラグトレイン』Vo. 歌愛ユキ
$ youtube-dl --get-title https://www.youtube.com/watch?v=UnIhRpIT7nc --add-header 'Accept-Language: es' --print-traffic # no translated version in spanish, return the default title
... Accept-Language:  es ...
稲葉曇『ラグトレイン』Vo. 歌愛ユキ

I am worried that your 'localized version' actually means 'the hardcoded en-US version'

It does, without the --add-header 'Accept-Language: es' flag. Perhaps the solution is not hardcoding the Accept-Language header in youtube-dl? But --add-header 'Accept-Language: es' as a flag is not so complicated, but feedback for making this nicer would be appreciated

One is asking for additional commandline switches for retrieving the title/desc in one, multiple or all available languages, like how it's currently done for subtitles.

I guess I missed this. This PR does not cover this request, as requesting multiple titles/desc requires multiple requests & would require a more complicated change. I believe all subtitles are shipped in a single request?

and may even be working against the goals of those issue reports.

Not sure what you mean by this. The fact that it is defaulting to the hardcoded en-us?.

All in all, I think you are right, and this PR needs a bit more to not just default to en-us.

Does de-hardcoding the default Accept-Language sound like a way forwards? I'm not sure how much garbage downloaded that makes way for. Something derived from locale.getlocale()?

[theultramage]

Thank you for the explanation. I've seen multiple reports point out that adding the accept language header had no effect whatsoever, and there was no workaround. You managed to find the cause and patch it in a way that makes the workaround possible, and perhaps opens up a way for future improvements. I was initially worried that just flipping it to default En, closing all the tickets and declaring the problem solved would make the devs complacent and the problem would get even less attention than before.

I think this PR is good enough for what it intends to do (assuming there are no other issues), but I would narrow down the list of closed issues to those that are directly addressed by the PR and do not call for any additional work.