A quick grep indicates that the string "MP4GetMetadataGrouping" does not occur anywhere in the libmp4v2 (actually libfaad) source code as fetched by "apt-get source libmp4v2-0".
A quick grep indicates that the string "MP4GetMetadata Grouping" does not occur anywhere in the libmp4v2 (actually libfaad) source code as fetched by "apt-get source libmp4v2-0".