feat(YouTube - Spoof video streams): Allow picking a default audio language track

[LisoUseInAIKyrios]

Allows picking a preferred default audio stream language.

[oSumAtrIX]

Why is the language only set for iOS spoofs? According to the linked issue in Android VR the audio also changes unintendedly.

[LisoUseInAIKyrios]

On checking again, the default audio language is changed for Android VR. Not sure why it didn't work earlier.

Edit: Android VR failed because it expects an uppercase language code.

[oSumAtrIX]

I am wondering, why the user has to manually select the language. What makes it hard to automatically behave like the unspoofed version? Isn't the system language used in the request by default? If so, it may be better to separate the patches and force the default app behaviour in the spoof video streams patch.

How it would work is that a new "Change default video language" patch would be added. It could work in relation to the spoof video stream so that when the patch is used, it would interface properly and change the default video language for spoofed streams accordingly. When the spoof stream patch is not used, the original request audio stream is changed

[LisoUseInAIKyrios]

The only problem with separating the patch, is right now this is a sub patch of the spoof stream patch. Including it requires including spoof stream, so they're not really separate.

If a way is figured out to change the default audio language without spoofing, then yes it definitely makes sense to make a new patch. It probably would not be difficult to change, if the code responsible was found. But it's simpler and less confusing if this is part of spoof stream since they're both intertwined.

Without this change spoofing should be picking the correct default audio stream, but the issue is using are getting served junk AI localized audio even in unpatched YouTube. So at least with this they can change the default.

[oSumAtrIX]

The Spoof Video Streams patch has a clear and specific purpose to fix playback functionality. Addressing YouTube's changes to the default audio language falls outside this patch's intended scope. While it’s true that YouTube allows users to change the audio language via the track menu, the Spoof Video Streams inadvertently breaks that functionality and so, this should be treated as a bug to be fixed rather than introducing a workaround in this PR.

To make a separate "Change Default Audio Language" patch, we need to hook into YouTube's code where it creates the request body. This would let us change the language there. A quick search for system APIs to get the current system language should help. We also already know how when we spoofed the request client version by overriding a field. The same class that holds this field also stores the language field, which is easy to override.

If supporting unspoofed streams isn’t needed (since it doesn't work without root anyways), the patch can be turned off when spoofing is off. This can be done by organizing the code properly to handle these cases. This just requires a bit of refactoring in this PR.

[LisoUseInAIKyrios]

I think I see where the language is set for non spoofed calls. I'll try refactoring into a separate patch.

[LisoUseInAIKyrios]

I tried replacing every instance of:

• Locale.getLanguage()
• Locale.toLanguageTag()
• Locale.getCountry()
• Locale.getISO3Language()
• Locale.getDisplayLanguage()
• Locale.getDisplayCountry()

And the default audio stream is still English.

I think the language parameter is coming from somewhere else, and perhaps it's sent from the Google account settings since users report the default audio language can be a foreign language even when the app is set to English.

@oSumAtrIX Merge this as-is? If the audio stream parameter can be found then refactoring will be easy, but until then this is about as good as it'll get.

[oSumAtrIX]

I found this (it was only set in one single place):

The language appeared in the client info object:

No other part of the request mentioned a language. I think changing this should yield the expected results. If not, then the patch can be merged as is.

[LisoUseInAIKyrios]

I remember trying to patch that specific method, and also patching every place that Locale.toLanguageTag() was used, and the default audio language still did not change.

But my YT account isn't affected by the localized language feature rollout, so maybe that's why.

I'll look into this more later, but for now will merge this since the feature is useful now.

[YT-Advanced]

On checking again, the default audio language is changed for Android VR. Not sure why it didn't work earlier.

Edit: Android VR failed because it expects an uppercase language code.

Uhm in my side (vi language code), I don't need to uppercase the language code to get default audio track language

[LisoUseInAIKyrios]

Android VR needs uppercase language code to be recognized.

Edit: android VR is broken with uppercase and spoofing fell over to iOS. Logging was lacking so it went unnoticed.

[YT-Advanced]

Android VR needs uppercase language code to be recognized.

I mean ANDROID_VR, I can use language code without uppercase. Moreover, in RVX, without uppercase, the default audio track language is still correct.

Example request: https://restninja.io/share/57e6cfd07b31448cf5799d196f660bbd02cd063f/0