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mpeg12.c
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1 /*
2  * MPEG-1/2 decoder
3  * Copyright (c) 2000, 2001 Fabrice Bellard
4  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * MPEG-1/2 decoder
26  */
27 
28 #define UNCHECKED_BITSTREAM_READER 1
29 
30 #include "libavutil/attributes.h"
31 #include "libavutil/avassert.h"
32 #include "libavutil/timecode.h"
33 
34 #include "internal.h"
35 #include "avcodec.h"
36 #include "dsputil.h"
37 #include "mpegvideo.h"
38 #include "error_resilience.h"
39 #include "mpeg12.h"
40 #include "mpeg12data.h"
41 #include "bytestream.h"
42 #include "vdpau_internal.h"
43 #include "thread.h"
44 
45 uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
46 
47 static const uint8_t table_mb_ptype[7][2] = {
48  { 3, 5 }, // 0x01 MB_INTRA
49  { 1, 2 }, // 0x02 MB_PAT
50  { 1, 3 }, // 0x08 MB_FOR
51  { 1, 1 }, // 0x0A MB_FOR|MB_PAT
52  { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
53  { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
54  { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
55 };
56 
57 static const uint8_t table_mb_btype[11][2] = {
58  { 3, 5 }, // 0x01 MB_INTRA
59  { 2, 3 }, // 0x04 MB_BACK
60  { 3, 3 }, // 0x06 MB_BACK|MB_PAT
61  { 2, 4 }, // 0x08 MB_FOR
62  { 3, 4 }, // 0x0A MB_FOR|MB_PAT
63  { 2, 2 }, // 0x0C MB_FOR|MB_BACK
64  { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
65  { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
66  { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
67  { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
68  { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
69 };
70 
71 #define INIT_2D_VLC_RL(rl, static_size)\
72 {\
73  static RL_VLC_ELEM rl_vlc_table[static_size];\
74  INIT_VLC_STATIC(&rl.vlc, TEX_VLC_BITS, rl.n + 2,\
75  &rl.table_vlc[0][1], 4, 2,\
76  &rl.table_vlc[0][0], 4, 2, static_size);\
77 \
78  rl.rl_vlc[0] = rl_vlc_table;\
79  init_2d_vlc_rl(&rl);\
80 }
81 
82 static av_cold void init_2d_vlc_rl(RLTable *rl)
83 {
84  int i;
85 
86  for (i = 0; i < rl->vlc.table_size; i++) {
87  int code = rl->vlc.table[i][0];
88  int len = rl->vlc.table[i][1];
89  int level, run;
90 
91  if (len == 0) { // illegal code
92  run = 65;
93  level = MAX_LEVEL;
94  } else if (len<0) { //more bits needed
95  run = 0;
96  level = code;
97  } else {
98  if (code == rl->n) { //esc
99  run = 65;
100  level = 0;
101  } else if (code == rl->n+1) { //eob
102  run = 0;
103  level = 127;
104  } else {
105  run = rl->table_run [code] + 1;
106  level = rl->table_level[code];
107  }
108  }
109  rl->rl_vlc[0][i].len = len;
110  rl->rl_vlc[0][i].level = level;
111  rl->rl_vlc[0][i].run = run;
112  }
113 }
114 
115 av_cold void ff_mpeg12_common_init(MpegEncContext *s)
116 {
117 
118  s->y_dc_scale_table =
119  s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
120 
121 }
122 
123 void ff_mpeg1_clean_buffers(MpegEncContext *s)
124 {
125  s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
126  s->last_dc[1] = s->last_dc[0];
127  s->last_dc[2] = s->last_dc[0];
128  memset(s->last_mv, 0, sizeof(s->last_mv));
129 }
130 
131 
132 /******************************************/
133 /* decoding */
134 
135 VLC ff_mv_vlc;
136 
137 VLC ff_dc_lum_vlc;
138 VLC ff_dc_chroma_vlc;
139 
140 VLC ff_mbincr_vlc;
141 VLC ff_mb_ptype_vlc;
142 VLC ff_mb_btype_vlc;
143 VLC ff_mb_pat_vlc;
144 
145 av_cold void ff_mpeg12_init_vlcs(void)
146 {
147  static int done = 0;
148 
149  if (!done) {
150  done = 1;
151 
152  INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
153  ff_mpeg12_vlc_dc_lum_bits, 1, 1,
154  ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
155  INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,
156  ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
157  ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
158  INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
159  &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
160  &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
161  INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
162  &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
163  &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
164  INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
165  &ff_mpeg12_mbPatTable[0][1], 2, 1,
166  &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
167 
168  INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
169  &table_mb_ptype[0][1], 2, 1,
170  &table_mb_ptype[0][0], 2, 1, 64);
171  INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
172  &table_mb_btype[0][1], 2, 1,
173  &table_mb_btype[0][0], 2, 1, 64);
174  ff_init_rl(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
175  ff_init_rl(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);
176 
177  INIT_2D_VLC_RL(ff_rl_mpeg1, 680);
178  INIT_2D_VLC_RL(ff_rl_mpeg2, 674);
179  }
180 }
181 
182 /**
183  * Find the end of the current frame in the bitstream.
184  * @return the position of the first byte of the next frame, or -1
185  */
186 int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
187 {
188  int i;
189  uint32_t state = pc->state;
190 
191  /* EOF considered as end of frame */
192  if (buf_size == 0)
193  return 0;
194 
195 /*
196  0 frame start -> 1/4
197  1 first_SEQEXT -> 0/2
198  2 first field start -> 3/0
199  3 second_SEQEXT -> 2/0
200  4 searching end
201 */
202 
203  for (i = 0; i < buf_size; i++) {
204  av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
205  if (pc->frame_start_found & 1) {
206  if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
207  pc->frame_start_found--;
208  else if (state == EXT_START_CODE + 2) {
209  if ((buf[i] & 3) == 3)
210  pc->frame_start_found = 0;
211  else
212  pc->frame_start_found = (pc->frame_start_found + 1) & 3;
213  }
214  state++;
215  } else {
216  i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
217  if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
218  i++;
219  pc->frame_start_found = 4;
220  }
221  if (state == SEQ_END_CODE) {
222  pc->frame_start_found = 0;
223  pc->state=-1;
224  return i+1;
225  }
226  if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
227  pc->frame_start_found = 0;
228  if (pc->frame_start_found < 4 && state == EXT_START_CODE)
229  pc->frame_start_found++;
230  if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
231  if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
232  pc->frame_start_found = 0;
233  pc->state = -1;
234  return i - 3;
235  }
236  }
237  if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
238  ff_fetch_timestamp(s, i - 3, 1);
239  }
240  }
241  }
242  pc->state = state;
243  return END_NOT_FOUND;
244 }
245 
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