The replaygain2 plugin does not detect Ogg Vorbis files as supported because it checks whether the first extension defined in File.EXTENSIONS is contained in a whitelist of supported file types.
But in Picard the OggVorbisFile file class as an empty EXTENSIONS, as ".ogg" is a generic extension used for various formats using the Ogg container. EXTENSIONS is meant for Picard's format detection logic.
Hence replace the extension based detection with a proper type check checking for the Picard file type being used.
The replaygain2 plugin does not detect Ogg Vorbis files as supported because it checks whether the first extension defined in
File.EXTENSIONSis contained in a whitelist of supported file types.But in Picard the
OggVorbisFilefile class as an emptyEXTENSIONS, as ".ogg" is a generic extension used for various formats using the Ogg container.EXTENSIONSis meant for Picard's format detection logic.Hence replace the extension based detection with a proper type check checking for the Picard file type being used.