lavc: implement an ATRAC9 decoder

Multimedia / FFmpeg - Rostislav Pehlivanov [gmail.com] - 3 July 2018 19:15 EDT

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.

755e618399 lavc: implement an ATRAC9 decoder
Changelog | 1 +
configure | 1 +
libavcodec/Makefile | 1 +
libavcodec/allcodecs.c | 1 +
libavcodec/atrac9dec.c | 929 +++++++++++++++++++++++++++
libavcodec/atrac9tab.h | 1626 +++++++++++++++++++++++++++++++++++++++++++++++
libavcodec/avcodec.h | 1 +
libavcodec/codec_desc.c | 7 +
libavcodec/utils.c | 1 +
libavcodec/version.h | 2 +-
10 files changed, 2569 insertions(+), 1 deletion(-)

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