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FFmpeg/libavcodec/dvdata.h
Andreas Rheinhardt 51ca74b525 avcodec/dvdec: Avoid stack buffers
Instead reuse the destination RL VLC as scratch space.
This is possible, because the (implicit) codes here are already
ordered from left-to-right in the tree and because the codelengths
are increasing, which implies that mapping from VLC entries to the
corresponding entries used to initialize the VLC is monotonically
increasing. This means that one can reuse the right end of the
destination RL VLC to store the tables used to initialize the VLC
with.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-09-07 00:07:45 +02:00

38 lines
1.2 KiB
C

/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_DVDATA_H
#define AVCODEC_DVDATA_H
#include <stdint.h>
extern const uint8_t ff_dv_zigzag248_direct[64];
extern const uint8_t ff_dv_quant_shifts[22][4];
extern const uint8_t ff_dv_quant_offset[4];
#define NB_DV_VLC 409
/* The number of entries with value zero in ff_dv_vlc_level. */
#define NB_DV_ZERO_LEVEL_ENTRIES 72
extern const uint8_t ff_dv_vlc_len[NB_DV_VLC];
extern const uint8_t ff_dv_vlc_run[NB_DV_VLC];
extern const uint8_t ff_dv_vlc_level[NB_DV_VLC];
#endif /* AVCODEC_DVDATA_H */