Libav
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 Libav.
7  *
8  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
28 #include "libavutil/attributes.h"
29 #include "internal.h"
30 #include "avcodec.h"
31 #include "dsputil.h"
32 #include "mpegvideo.h"
33 #include "error_resilience.h"
34 #include "mpeg12.h"
35 #include "mpeg12data.h"
36 #include "bytestream.h"
37 #include "thread.h"
38 
40 
41 static const uint8_t table_mb_ptype[7][2] = {
42  { 3, 5 }, // 0x01 MB_INTRA
43  { 1, 2 }, // 0x02 MB_PAT
44  { 1, 3 }, // 0x08 MB_FOR
45  { 1, 1 }, // 0x0A MB_FOR|MB_PAT
46  { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
47  { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
48  { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
49 };
50 
51 static const uint8_t table_mb_btype[11][2] = {
52  { 3, 5 }, // 0x01 MB_INTRA
53  { 2, 3 }, // 0x04 MB_BACK
54  { 3, 3 }, // 0x06 MB_BACK|MB_PAT
55  { 2, 4 }, // 0x08 MB_FOR
56  { 3, 4 }, // 0x0A MB_FOR|MB_PAT
57  { 2, 2 }, // 0x0C MB_FOR|MB_BACK
58  { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
59  { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
60  { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
61  { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
62  { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
63 };
64 
65 #define INIT_2D_VLC_RL(rl, static_size)\
66 {\
67  static RL_VLC_ELEM rl_vlc_table[static_size];\
68  INIT_VLC_STATIC(&rl.vlc, TEX_VLC_BITS, rl.n + 2,\
69  &rl.table_vlc[0][1], 4, 2,\
70  &rl.table_vlc[0][0], 4, 2, static_size);\
71 \
72  rl.rl_vlc[0] = rl_vlc_table;\
73  init_2d_vlc_rl(&rl);\
74 }
75 
76 static av_cold void init_2d_vlc_rl(RLTable *rl)
77 {
78  int i;
79 
80  for (i = 0; i < rl->vlc.table_size; i++) {
81  int code = rl->vlc.table[i][0];
82  int len = rl->vlc.table[i][1];
83  int level, run;
84 
85  if (len == 0) { // illegal code
86  run = 65;
87  level = MAX_LEVEL;
88  } else if (len<0) { //more bits needed
89  run = 0;
90  level = code;
91  } else {
92  if (code == rl->n) { //esc
93  run = 65;
94  level = 0;
95  } else if (code == rl->n+1) { //eob
96  run = 0;
97  level = 127;
98  } else {
99  run = rl->table_run [code] + 1;
100  level = rl->table_level[code];
101  }
102  }
103  rl->rl_vlc[0][i].len = len;
104  rl->rl_vlc[0][i].level = level;
105  rl->rl_vlc[0][i].run = run;
106  }
107 }
108 
110 {
111 
112  s->y_dc_scale_table =
114 
115 }
116 
118 {
119  s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
120  s->last_dc[1] = s->last_dc[0];
121  s->last_dc[2] = s->last_dc[0];
122  memset(s->last_mv, 0, sizeof(s->last_mv));
123 }
124 
125 
126 /******************************************/
127 /* decoding */
128 
130 
133 
138 
140 {
141  static int done = 0;
142 
143  if (!done) {
144  done = 1;
145 
146  INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
148  ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
149  INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,
151  ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
152  INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
153  &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
154  &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
155  INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
156  &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
157  &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
158  INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
159  &ff_mpeg12_mbPatTable[0][1], 2, 1,
160  &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
161 
162  INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
163  &table_mb_ptype[0][1], 2, 1,
164  &table_mb_ptype[0][0], 2, 1, 64);
165  INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
166  &table_mb_btype[0][1], 2, 1,
167  &table_mb_btype[0][0], 2, 1, 64);
170 
173  }
174 }
175 
180 int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
181 {
182  int i;
183  uint32_t state = pc->state;
184 
185  /* EOF considered as end of frame */
186  if (buf_size == 0)
187  return 0;
188 
189 /*
190  0 frame start -> 1/4
191  1 first_SEQEXT -> 0/2
192  2 first field start -> 3/0
193  3 second_SEQEXT -> 2/0
194  4 searching end
195 */
196 
197  for (i = 0; i < buf_size; i++) {
198  assert(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
199  if (pc->frame_start_found & 1) {
200  if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
201  pc->frame_start_found--;
202  else if (state == EXT_START_CODE + 2) {
203  if ((buf[i] & 3) == 3)
204  pc->frame_start_found = 0;
205  else
206  pc->frame_start_found = (pc->frame_start_found + 1) & 3;
207  }
208  state++;
209  } else {
210  i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
211  if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
212  i++;
213  pc->frame_start_found = 4;
214  }
215  if (state == SEQ_END_CODE) {
216  pc->frame_start_found = 0;
217  pc->state=-1;
218  return i+1;
219  }
220  if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
221  pc->frame_start_found = 0;
222  if (pc->frame_start_found < 4 && state == EXT_START_CODE)
223  pc->frame_start_found++;
224  if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
225  if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
226  pc->frame_start_found = 0;
227  pc->state = -1;
228  return i - 3;
229  }
230  }
231  if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
232  ff_fetch_timestamp(s, i - 3, 1);
233  }
234  }
235  }
236  pc->state = state;
237  return END_NOT_FOUND;
238 }