Just remove some dead variable assignments, unneeded variables and
change the FFMAX order to something more readable. Still identical.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Much simpler than regular decoding, does allow for 5.1 and 7.1
streams to be decoded without desync.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Unlike the range, the gradient start value does not have to be lower
than the end value.
Does allow more files to be correctly decoded without errors.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
This commit implements a full ATRAC9 decoder, a simple low-delay codec
developed by Sony and used in most PSVita games, some PS3 games and some
PS4 games. Its similar to AAC in that it uses Huffman coded scalefactors
but instead of vector quantization it just Huffman codes the spectral
coefficients (in a way similar to how Opus splits band energy coding
into coarse and fine precision). It opts to write rather large Huffman
codes by packing several small coefficients into one Huffman coded
symbol, though I don't believe this increases efficiency at all.
Band extension implements SBC in a simple way, first it mirrors the
lower spectrum onto the higher frequencies and then it uses one of 5
filters to shape it. Noise substitution is implemented via 2 of them.
Unlike previous ATRAC codecs, there's no QMF, this is a standard MDCT
codec.
Based off of the reverse engineering work of Alex Barney.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
