mirror of
https://git.ffmpeg.org/ffmpeg.git
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245 lines
7.8 KiB
C
245 lines
7.8 KiB
C
/*
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* MPEG-1/2 decoder
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* Copyright (c) 2000, 2001 Fabrice Bellard
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* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* MPEG-1/2 decoder
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*/
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#define UNCHECKED_BITSTREAM_READER 1
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#include "libavutil/attributes.h"
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#include "libavutil/avassert.h"
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#include "libavutil/timecode.h"
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#include "internal.h"
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#include "avcodec.h"
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#include "mpegvideo.h"
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#include "error_resilience.h"
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#include "mpeg12.h"
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#include "mpeg12data.h"
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#include "bytestream.h"
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#include "vdpau_internal.h"
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#include "thread.h"
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uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
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static const uint8_t table_mb_ptype[7][2] = {
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{ 3, 5 }, // 0x01 MB_INTRA
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{ 1, 2 }, // 0x02 MB_PAT
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{ 1, 3 }, // 0x08 MB_FOR
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{ 1, 1 }, // 0x0A MB_FOR|MB_PAT
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{ 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
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{ 1, 5 }, // 0x12 MB_QUANT|MB_PAT
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{ 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
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};
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static const uint8_t table_mb_btype[11][2] = {
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{ 3, 5 }, // 0x01 MB_INTRA
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{ 2, 3 }, // 0x04 MB_BACK
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{ 3, 3 }, // 0x06 MB_BACK|MB_PAT
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{ 2, 4 }, // 0x08 MB_FOR
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{ 3, 4 }, // 0x0A MB_FOR|MB_PAT
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{ 2, 2 }, // 0x0C MB_FOR|MB_BACK
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{ 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
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{ 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
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{ 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
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{ 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
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{ 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
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};
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#define INIT_2D_VLC_RL(rl, static_size)\
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{\
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static RL_VLC_ELEM rl_vlc_table[static_size];\
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rl.rl_vlc[0] = rl_vlc_table;\
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init_2d_vlc_rl(&rl, static_size);\
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}
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static av_cold void init_2d_vlc_rl(RLTable *rl, unsigned static_size)
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{
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int i;
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VLC_TYPE table[680][2] = {{0}};
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VLC vlc = { .table = table, .table_allocated = static_size };
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av_assert0(static_size <= FF_ARRAY_ELEMS(table));
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init_vlc(&vlc, TEX_VLC_BITS, rl->n + 2, &rl->table_vlc[0][1], 4, 2, &rl->table_vlc[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);
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for (i = 0; i < vlc.table_size; i++) {
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int code = vlc.table[i][0];
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int len = vlc.table[i][1];
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int level, run;
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if (len == 0) { // illegal code
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run = 65;
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level = MAX_LEVEL;
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} else if (len<0) { //more bits needed
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run = 0;
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level = code;
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} else {
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if (code == rl->n) { //esc
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run = 65;
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level = 0;
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} else if (code == rl->n+1) { //eob
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run = 0;
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level = 127;
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} else {
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run = rl->table_run [code] + 1;
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level = rl->table_level[code];
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}
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}
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rl->rl_vlc[0][i].len = len;
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rl->rl_vlc[0][i].level = level;
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rl->rl_vlc[0][i].run = run;
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}
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}
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av_cold void ff_mpeg12_common_init(MpegEncContext *s)
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{
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s->y_dc_scale_table =
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s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
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}
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void ff_mpeg1_clean_buffers(MpegEncContext *s)
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{
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s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
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s->last_dc[1] = s->last_dc[0];
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s->last_dc[2] = s->last_dc[0];
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memset(s->last_mv, 0, sizeof(s->last_mv));
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}
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/******************************************/
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/* decoding */
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VLC ff_mv_vlc;
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VLC ff_dc_lum_vlc;
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VLC ff_dc_chroma_vlc;
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VLC ff_mbincr_vlc;
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VLC ff_mb_ptype_vlc;
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VLC ff_mb_btype_vlc;
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VLC ff_mb_pat_vlc;
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av_cold void ff_mpeg12_init_vlcs(void)
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{
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static int done = 0;
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if (!done) {
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done = 1;
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INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
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ff_mpeg12_vlc_dc_lum_bits, 1, 1,
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ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
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INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,
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ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
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ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
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INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
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&ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
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&ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
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INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
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&ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
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&ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
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INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
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&ff_mpeg12_mbPatTable[0][1], 2, 1,
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&ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
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INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
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&table_mb_ptype[0][1], 2, 1,
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&table_mb_ptype[0][0], 2, 1, 64);
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INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
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&table_mb_btype[0][1], 2, 1,
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&table_mb_btype[0][0], 2, 1, 64);
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ff_init_rl(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
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ff_init_rl(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);
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INIT_2D_VLC_RL(ff_rl_mpeg1, 680);
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INIT_2D_VLC_RL(ff_rl_mpeg2, 674);
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}
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}
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/**
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* Find the end of the current frame in the bitstream.
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* @return the position of the first byte of the next frame, or -1
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*/
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int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
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{
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int i;
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uint32_t state = pc->state;
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/* EOF considered as end of frame */
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if (buf_size == 0)
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return 0;
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/*
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0 frame start -> 1/4
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1 first_SEQEXT -> 0/2
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2 first field start -> 3/0
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3 second_SEQEXT -> 2/0
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4 searching end
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*/
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for (i = 0; i < buf_size; i++) {
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av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
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if (pc->frame_start_found & 1) {
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if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
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pc->frame_start_found--;
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else if (state == EXT_START_CODE + 2) {
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if ((buf[i] & 3) == 3)
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pc->frame_start_found = 0;
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else
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pc->frame_start_found = (pc->frame_start_found + 1) & 3;
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}
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state++;
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} else {
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i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
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if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
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i++;
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pc->frame_start_found = 4;
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}
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if (state == SEQ_END_CODE) {
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pc->frame_start_found = 0;
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pc->state=-1;
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return i+1;
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}
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if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
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pc->frame_start_found = 0;
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if (pc->frame_start_found < 4 && state == EXT_START_CODE)
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pc->frame_start_found++;
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if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
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if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
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pc->frame_start_found = 0;
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pc->state = -1;
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return i - 3;
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}
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}
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if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
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ff_fetch_timestamp(s, i - 3, 1);
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}
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}
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}
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pc->state = state;
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return END_NOT_FOUND;
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}
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