Andreas Rheinhardt fefe2cbbf2 avcodec/smacker: Improve creating Huffman VLC tables ...

The Smacker Huffman tables are already stored in a tree-like structure;
in particular, they are naturally ordered from left to right in the
tree and are therefore suitable to be initialized by
ff_init_vlc_from_lengths() which avoids traversing the data twice in
order to sort only the codes that are so long that they need into a
subtable.

This improves performance (and reduces codesize): For the sample from
ticket #2425 the number of decicycles for parsing and creating the VLCs
in smka_decode_frame() decreased from 412322 to 359152 (tested with
10 runs each looping 20 times over the file).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

2020-12-08 17:51:44 +01:00

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