atrac: Add missing av_cold.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
atrac: Update copyright info and file description.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
atrac: Move doxygen comments to the header

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
atrac: limit line length to 80 chars

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
atrac3: Rename GainInfo to AtracGainInfo

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
atrac3: rename num_gain_data to num_points

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
atrac3/decode_gain_control: cosmetics

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
atrac3: Generalize gain compensation code

Move it to the ATRAC common code, so it can be reused
in the umpcoming ATRAC3+ decoder.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>