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ffmpeg/libavcodec/mpeg12.c

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/*
* MPEG-1/2 decoder
* Copyright (c) 2000, 2001 Fabrice Bellard
* Copyright (c) 2002-2004 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
*/
/**
* @file
* MPEG-1/2 decoder
*/
#define UNCHECKED_BITSTREAM_READER 1
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/timecode.h"
#include "internal.h"
#include "avcodec.h"
#include "dsputil.h"
#include "mpegvideo.h"
#include "error_resilience.h"
#include "mpeg12.h"
#include "mpeg12data.h"
#include "mpeg12decdata.h"
#include "bytestream.h"
#include "vdpau_internal.h"
#include "xvmc_internal.h"
#include "thread.h"
uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
#define INIT_2D_VLC_RL(rl, static_size)\
{\
static RL_VLC_ELEM rl_vlc_table[static_size];\
INIT_VLC_STATIC(&rl.vlc, TEX_VLC_BITS, rl.n + 2,\
&rl.table_vlc[0][1], 4, 2,\
&rl.table_vlc[0][0], 4, 2, static_size);\
\
rl.rl_vlc[0] = rl_vlc_table;\
init_2d_vlc_rl(&rl);\
}
static av_cold void init_2d_vlc_rl(RLTable *rl)
{
int i;
for (i = 0; i < rl->vlc.table_size; i++) {
int code = rl->vlc.table[i][0];
int len = rl->vlc.table[i][1];
int level, run;
if (len == 0) { // illegal code
run = 65;
level = MAX_LEVEL;
} else if (len<0) { //more bits needed
run = 0;
level = code;
} else {
if (code == rl->n) { //esc
run = 65;
level = 0;
} else if (code == rl->n+1) { //eob
run = 0;
level = 127;
} else {
run = rl->table_run [code] + 1;
level = rl->table_level[code];
}
}
rl->rl_vlc[0][i].len = len;
rl->rl_vlc[0][i].level = level;
rl->rl_vlc[0][i].run = run;
}
}
av_cold void ff_mpeg12_common_init(MpegEncContext *s)
{
s->y_dc_scale_table =
s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
}
void ff_mpeg1_clean_buffers(MpegEncContext *s)
{
s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
s->last_dc[1] = s->last_dc[0];
s->last_dc[2] = s->last_dc[0];
memset(s->last_mv, 0, sizeof(s->last_mv));
}
/******************************************/
/* decoding */
VLC ff_mv_vlc;
VLC ff_dc_lum_vlc;
VLC ff_dc_chroma_vlc;
VLC ff_mbincr_vlc;
VLC ff_mb_ptype_vlc;
VLC ff_mb_btype_vlc;
VLC ff_mb_pat_vlc;
av_cold void ff_mpeg12_init_vlcs(void)
{
static int done = 0;
if (!done) {
done = 1;
INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
ff_mpeg12_vlc_dc_lum_bits, 1, 1,
ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,
ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
&ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
&ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
&ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
&ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
&ff_mpeg12_mbPatTable[0][1], 2, 1,
&ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
&table_mb_ptype[0][1], 2, 1,
&table_mb_ptype[0][0], 2, 1, 64);
INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
&table_mb_btype[0][1], 2, 1,
&table_mb_btype[0][0], 2, 1, 64);
ff_init_rl(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
ff_init_rl(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);
INIT_2D_VLC_RL(ff_rl_mpeg1, 680);
INIT_2D_VLC_RL(ff_rl_mpeg2, 674);
}
}
/**
* Find the end of the current frame in the bitstream.
* @return the position of the first byte of the next frame, or -1
*/
int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
{
int i;
uint32_t state = pc->state;
/* EOF considered as end of frame */
if (buf_size == 0)
return 0;
/*
0 frame start -> 1/4
1 first_SEQEXT -> 0/2
2 first field start -> 3/0
3 second_SEQEXT -> 2/0
4 searching end
*/
for (i = 0; i < buf_size; i++) {
av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
if (pc->frame_start_found & 1) {
if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
pc->frame_start_found--;
else if (state == EXT_START_CODE + 2) {
if ((buf[i] & 3) == 3)
pc->frame_start_found = 0;
else
pc->frame_start_found = (pc->frame_start_found + 1) & 3;
}
state++;
} else {
i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
i++;
pc->frame_start_found = 4;
}
if (state == SEQ_END_CODE) {
pc->frame_start_found = 0;
pc->state=-1;
return i+1;
}
if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
pc->frame_start_found = 0;
if (pc->frame_start_found < 4 && state == EXT_START_CODE)
pc->frame_start_found++;
if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
pc->frame_start_found = 0;
pc->state = -1;
return i - 3;
}
}
if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
ff_fetch_timestamp(s, i - 3, 1);
}
}
}
pc->state = state;
return END_NOT_FOUND;
}
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