Fail to identify Opus files with the .ogg extension

[Ambrevar]

I have Opus files with the .ogg extension and Strawberry (which leverages taglib) fails to detect them.
If I change the file extension to .opus, it works.

I've reported this on the Strawberry bugtracker (strawberrymusicplayer/strawberry#712 (comment)) and they forwarded me here.

[ufleisch]

When using the standard FileRef(FileName fileName, ...) constructor, it will call FileRef::parse(FileName fileName, ...) which will first try detectByResolvers(), then detectByExtension(), and finally detectByContent(). The problem here is that detectByExtension() will return a non null TagLib::File* pointer, actually an invalid Ogg/Vorbis file, and the detectByContent() will not be tried. This behavior could be changed by deleting the returned TagLib::File* if !d->file->isValid(), such a check for validity is also done in detectByContent() and should be added to detectByExtension() and detectByResolvers().

A backwards-compatible solution would be if Strawberry implement a subclass of TagLib::IOStream with an improved file type detection. This could also be implemented in a way to work with TagLib versions < 1.12 because the "Enabled FileRef to detect file types based on the stream content" feature is only available in TagLib 1.12.

[Ambrevar]

@jonaski What do you think?

[ufleisch]

Should be fixed by #1013.

[Ambrevar]

Thanks!