ff_private: set more ASBD fields before calling FormatInfo
ff_private: set more ASBD fields before calling FormatInfo

This is required for FLAC.

Some drive-by cosmetic changes.

MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian,MaddTheSane/perian