Each ChannelElement contains exactly one SpectralBandReplication
structure; the latter structure contains lots of buffers
whose size depend upon USE_FIXED (i.e. AAC_FLOAT arrays).
This complicates deduplicating the parts of the AAC decoder
that are duplicated between the fixed-point and the floating
point decoder.
In order to fix this, the SpectralBandReplication structure
will be moved from the part of ChannelElement visible to
the common code. Therefore the ff_aac_sbr_* functions
are ported to accept a ChannelElement*; they will then have
to translate that to the corresponding SpectralBandReplication*
themselves (which is possible, because there are floating-point
and fixed-point versions of these functions).
While just at it, also ensure that these functions are properly
namespaced.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>