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FFmpeg/libavcodec/mpeg4video.h
Andreas Rheinhardt 832ead2ec4 avcodec/mpeg4videodec: Fix data race when initializing VLCs 
Both the MPEG-4 parser as well as the decoder initialized
several VLCs. There is a "static int done = 0;" in order to
guard against initializing these multiple times, but this does
not work when several threads try to initialize these VLCs
concurrently, which can happen when initializing several parsers
at the same time (they don't use the global lock that is used
for codecs without the FF_CODEC_CAP_INIT_THREADSAFE cap; actually,
they don't use any lock at all).

Since ff_mpeg4_decode_picture_header() now aborts early when called
from the parser, it no longer needs to have these VLCs initialized
at all. This commit therefore does exactly this.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-01-09 09:32:53 +01:00

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8.1 KiB
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/*
* MPEG-4 encoder/decoder internal header.
* Copyright (c) 2000,2001 Fabrice Bellard
* Copyright (c) 2002-2010 Michael Niedermayer <michaelni@gmx.at>
*
* 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_MPEG4VIDEO_H
#define AVCODEC_MPEG4VIDEO_H
#include <stdint.h>
#include "get_bits.h"
#include "mpegvideo.h"
#include "rl.h"
// shapes
#define RECT_SHAPE 0
#define BIN_SHAPE 1
#define BIN_ONLY_SHAPE 2
#define GRAY_SHAPE 3
#define SIMPLE_VO_TYPE 1
#define CORE_VO_TYPE 3
#define MAIN_VO_TYPE 4
#define NBIT_VO_TYPE 5
#define ARTS_VO_TYPE 10
#define ACE_VO_TYPE 12
#define SIMPLE_STUDIO_VO_TYPE 14
#define CORE_STUDIO_VO_TYPE 15
#define ADV_SIMPLE_VO_TYPE 17
#define VOT_VIDEO_ID 1
#define VOT_STILL_TEXTURE_ID 2
// aspect_ratio_info
#define EXTENDED_PAR 15
//vol_sprite_usage / sprite_enable
#define STATIC_SPRITE 1
#define GMC_SPRITE 2
#define MOTION_MARKER 0x1F001
#define DC_MARKER 0x6B001
#define VOS_STARTCODE 0x1B0
#define USER_DATA_STARTCODE 0x1B2
#define GOP_STARTCODE 0x1B3
#define VISUAL_OBJ_STARTCODE 0x1B5
#define VOP_STARTCODE 0x1B6
#define SLICE_STARTCODE 0x1B7
#define EXT_STARTCODE 0x1B8
#define QUANT_MATRIX_EXT_ID 0x3
/* smaller packets likely don't contain a real frame */
#define MAX_NVOP_SIZE 19
typedef struct Mpeg4DecContext {
MpegEncContext m;
/// number of bits to represent the fractional part of time
int time_increment_bits;
int shape;
int vol_sprite_usage;
int sprite_brightness_change;
int num_sprite_warping_points;
/// sprite trajectory points
uint16_t sprite_traj[4][2];
/// sprite shift [isChroma]
int sprite_shift[2];
// reversible vlc
int rvlc;
/// could this stream contain resync markers
int resync_marker;
/// time distance of first I -> B, used for interlaced B-frames
int t_frame;
int new_pred;
int enhancement_type;
int scalability;
int use_intra_dc_vlc;
/// QP above which the ac VLC should be used for intra dc
int intra_dc_threshold;
/* bug workarounds */
int divx_version;
int divx_build;
int xvid_build;
int lavc_build;
/// flag for having shown the warning about invalid Divx B-frames
int showed_packed_warning;
/** does the stream contain the low_delay flag,
* used to work around buggy encoders. */
int vol_control_parameters;
int cplx_estimation_trash_i;
int cplx_estimation_trash_p;
int cplx_estimation_trash_b;
int rgb;
} Mpeg4DecContext;
static const uint8_t mpeg4_block_count[4] = {0, 6, 8, 12};
/* dc encoding for MPEG-4 */
extern const uint8_t ff_mpeg4_DCtab_lum[13][2];
extern const uint8_t ff_mpeg4_DCtab_chrom[13][2];
extern const uint16_t ff_mpeg4_intra_vlc[103][2];
extern const int8_t ff_mpeg4_intra_level[102];
extern const int8_t ff_mpeg4_intra_run[102];
extern RLTable ff_mpeg4_rl_intra;
void ff_mpeg4_init_rl_intra(void);
/* Note this is identical to the intra rvlc except that it is reordered. */
extern RLTable ff_rvlc_rl_inter;
extern RLTable ff_rvlc_rl_intra;
extern const uint8_t ff_sprite_trajectory_lens[15];
extern const uint8_t ff_mb_type_b_tab[4][2];
/* these matrixes will be permuted for the idct */
extern const int16_t ff_mpeg4_default_intra_matrix[64];
extern const int16_t ff_mpeg4_default_non_intra_matrix[64];
extern const uint8_t ff_mpeg4_y_dc_scale_table[32];
extern const uint8_t ff_mpeg4_c_dc_scale_table[32];
extern const uint16_t ff_mpeg4_resync_prefix[8];
extern const uint8_t ff_mpeg4_dc_threshold[8];
extern const uint8_t ff_mpeg4_studio_dc_luma[19][2];
extern const uint8_t ff_mpeg4_studio_dc_chroma[19][2];
extern const uint8_t ff_mpeg4_studio_intra[12][24][2];
void ff_mpeg4_encode_mb(MpegEncContext *s,
int16_t block[6][64],
int motion_x, int motion_y);
void ff_mpeg4_pred_ac(MpegEncContext *s, int16_t *block, int n,
int dir);
void ff_set_mpeg4_time(MpegEncContext *s);
int ff_mpeg4_encode_picture_header(MpegEncContext *s, int picture_number);
int ff_mpeg4_decode_picture_header(Mpeg4DecContext *ctx, GetBitContext *gb,
int header, int parse_only);
void ff_mpeg4_encode_video_packet_header(MpegEncContext *s);
void ff_mpeg4_clean_buffers(MpegEncContext *s);
void ff_mpeg4_stuffing(PutBitContext *pbc);
void ff_mpeg4_init_partitions(MpegEncContext *s);
void ff_mpeg4_merge_partitions(MpegEncContext *s);
void ff_clean_mpeg4_qscales(MpegEncContext *s);
int ff_mpeg4_decode_partitions(Mpeg4DecContext *ctx);
int ff_mpeg4_get_video_packet_prefix_length(MpegEncContext *s);
int ff_mpeg4_decode_video_packet_header(Mpeg4DecContext *ctx);
int ff_mpeg4_decode_studio_slice_header(Mpeg4DecContext *ctx);
void ff_mpeg4_init_direct_mv(MpegEncContext *s);
int ff_mpeg4_workaround_bugs(AVCodecContext *avctx);
int ff_mpeg4_frame_end(AVCodecContext *avctx, const uint8_t *buf, int buf_size);
/**
* @return the mb_type
*/
int ff_mpeg4_set_direct_mv(MpegEncContext *s, int mx, int my);
#if 0 //3IV1 is quite rare and it slows things down a tiny bit
#define IS_3IV1 s->codec_tag == AV_RL32("3IV1")
#else
#define IS_3IV1 0
#endif
/**
* Predict the dc.
* encoding quantized level -> quantized diff
* decoding quantized diff -> quantized level
* @param n block index (0-3 are luma, 4-5 are chroma)
* @param dir_ptr pointer to an integer where the prediction direction will be stored
*/
static inline int ff_mpeg4_pred_dc(MpegEncContext *s, int n, int level,
int *dir_ptr, int encoding)
{
int a, b, c, wrap, pred, scale, ret;
int16_t *dc_val;
/* find prediction */
if (n < 4)
scale = s->y_dc_scale;
else
scale = s->c_dc_scale;
if (IS_3IV1)
scale = 8;
wrap = s->block_wrap[n];
dc_val = s->dc_val[0] + s->block_index[n];
/* B C
* A X
*/
a = dc_val[-1];
b = dc_val[-1 - wrap];
c = dc_val[-wrap];
/* outside slice handling (we can't do that by memset as we need the
* dc for error resilience) */
if (s->first_slice_line && n != 3) {
if (n != 2)
b = c = 1024;
if (n != 1 && s->mb_x == s->resync_mb_x)
b = a = 1024;
}
if (s->mb_x == s->resync_mb_x && s->mb_y == s->resync_mb_y + 1) {
if (n == 0 || n == 4 || n == 5)
b = 1024;
}
if (abs(a - b) < abs(b - c)) {
pred = c;
*dir_ptr = 1; /* top */
} else {
pred = a;
*dir_ptr = 0; /* left */
}
/* we assume pred is positive */
pred = FASTDIV((pred + (scale >> 1)), scale);
if (encoding) {
ret = level - pred;
} else {
level += pred;
ret = level;
}
level *= scale;
if (level & (~2047)) {
if (!s->encoding && (s->avctx->err_recognition & (AV_EF_BITSTREAM | AV_EF_AGGRESSIVE))) {
if (level < 0) {
av_log(s->avctx, AV_LOG_ERROR,
"dc<0 at %dx%d\n", s->mb_x, s->mb_y);
return AVERROR_INVALIDDATA;
}
if (level > 2048 + scale) {
av_log(s->avctx, AV_LOG_ERROR,
"dc overflow at %dx%d\n", s->mb_x, s->mb_y);
return AVERROR_INVALIDDATA;
}
}
if (level < 0)
level = 0;
else if (!(s->workaround_bugs & FF_BUG_DC_CLIP))
level = 2047;
}
dc_val[0] = level;
return ret;
}
#endif /* AVCODEC_MPEG4VIDEO_H */
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