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 #include "libavutil/thread.h"
34
35 #include "internal.h"
36 #include "avcodec.h"
37 #include "mpegvideo.h"
38 #include "error_resilience.h"
39 #include "mpeg12.h"
40 #include "mpeg12data.h"
41 #include "mpegvideodata.h"
42 #include "bytestream.h"
43 #include "thread.h"
44
45 static const uint8_t table_mb_ptype[7][2] = {
46 { 3, 5 }, // 0x01 MB_INTRA
47 { 1, 2 }, // 0x02 MB_PAT
48 { 1, 3 }, // 0x08 MB_FOR
49 { 1, 1 }, // 0x0A MB_FOR|MB_PAT
50 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
51 { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
52 { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
53 };
54
55 static const uint8_t table_mb_btype[11][2] = {
56 { 3, 5 }, // 0x01 MB_INTRA
57 { 2, 3 }, // 0x04 MB_BACK
58 { 3, 3 }, // 0x06 MB_BACK|MB_PAT
59 { 2, 4 }, // 0x08 MB_FOR
60 { 3, 4 }, // 0x0A MB_FOR|MB_PAT
61 { 2, 2 }, // 0x0C MB_FOR|MB_BACK
62 { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
63 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
64 { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
65 { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
66 { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
67 };
68
ff_init_2d_vlc_rl(RLTable * rl,unsigned static_size,int flags)69 av_cold void ff_init_2d_vlc_rl(RLTable *rl, unsigned static_size, int flags)
70 {
71 int i;
72 VLC_TYPE table[680][2] = {{0}};
73 VLC vlc = { .table = table, .table_allocated = static_size };
74 av_assert0(static_size <= FF_ARRAY_ELEMS(table));
75 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 | flags);
76
77 for (i = 0; i < vlc.table_size; i++) {
78 int code = vlc.table[i][0];
79 int len = vlc.table[i][1];
80 int level, run;
81
82 if (len == 0) { // illegal code
83 run = 65;
84 level = MAX_LEVEL;
85 } else if (len<0) { //more bits needed
86 run = 0;
87 level = code;
88 } else {
89 if (code == rl->n) { //esc
90 run = 65;
91 level = 0;
92 } else if (code == rl->n+1) { //eob
93 run = 0;
94 level = 127;
95 } else {
96 run = rl->table_run [code] + 1;
97 level = rl->table_level[code];
98 }
99 }
100 rl->rl_vlc[0][i].len = len;
101 rl->rl_vlc[0][i].level = level;
102 rl->rl_vlc[0][i].run = run;
103 }
104 }
105
ff_mpeg12_common_init(MpegEncContext * s)106 av_cold void ff_mpeg12_common_init(MpegEncContext *s)
107 {
108
109 s->y_dc_scale_table =
110 s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
111
112 }
113
ff_mpeg1_clean_buffers(MpegEncContext * s)114 void ff_mpeg1_clean_buffers(MpegEncContext *s)
115 {
116 s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
117 s->last_dc[1] = s->last_dc[0];
118 s->last_dc[2] = s->last_dc[0];
119 memset(s->last_mv, 0, sizeof(s->last_mv));
120 }
121
122
123 /******************************************/
124 /* decoding */
125
126 VLC ff_mv_vlc;
127
128 VLC ff_dc_lum_vlc;
129 VLC ff_dc_chroma_vlc;
130
131 VLC ff_mbincr_vlc;
132 VLC ff_mb_ptype_vlc;
133 VLC ff_mb_btype_vlc;
134 VLC ff_mb_pat_vlc;
135
mpeg12_init_vlcs(void)136 static av_cold void mpeg12_init_vlcs(void)
137 {
138 INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
139 ff_mpeg12_vlc_dc_lum_bits, 1, 1,
140 ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
141 INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,
142 ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
143 ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
144 INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
145 &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
146 &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 266);
147 INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
148 &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
149 &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
150 INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
151 &ff_mpeg12_mbPatTable[0][1], 2, 1,
152 &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
153
154 INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
155 &table_mb_ptype[0][1], 2, 1,
156 &table_mb_ptype[0][0], 2, 1, 64);
157 INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
158 &table_mb_btype[0][1], 2, 1,
159 &table_mb_btype[0][0], 2, 1, 64);
160
161 INIT_2D_VLC_RL(ff_rl_mpeg1, 680, 0);
162 INIT_2D_VLC_RL(ff_rl_mpeg2, 674, 0);
163 }
164
ff_mpeg12_init_vlcs(void)165 av_cold void ff_mpeg12_init_vlcs(void)
166 {
167 static AVOnce init_static_once = AV_ONCE_INIT;
168 ff_thread_once(&init_static_once, mpeg12_init_vlcs);
169 }
170
171 /**
172 * Find the end of the current frame in the bitstream.
173 * @return the position of the first byte of the next frame, or -1
174 */
ff_mpeg1_find_frame_end(ParseContext * pc,const uint8_t * buf,int buf_size,AVCodecParserContext * s)175 int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
176 {
177 int i;
178 uint32_t state = pc->state;
179
180 /* EOF considered as end of frame */
181 if (buf_size == 0)
182 return 0;
183
184 /*
185 0 frame start -> 1/4
186 1 first_SEQEXT -> 0/2
187 2 first field start -> 3/0
188 3 second_SEQEXT -> 2/0
189 4 searching end
190 */
191
192 for (i = 0; i < buf_size; i++) {
193 av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
194 if (pc->frame_start_found & 1) {
195 if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
196 pc->frame_start_found--;
197 else if (state == EXT_START_CODE + 2) {
198 if ((buf[i] & 3) == 3)
199 pc->frame_start_found = 0;
200 else
201 pc->frame_start_found = (pc->frame_start_found + 1) & 3;
202 }
203 state++;
204 } else {
205 i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
206 if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
207 i++;
208 pc->frame_start_found = 4;
209 }
210 if (state == SEQ_END_CODE) {
211 pc->frame_start_found = 0;
212 pc->state=-1;
213 return i+1;
214 }
215 if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
216 pc->frame_start_found = 0;
217 if (pc->frame_start_found < 4 && state == EXT_START_CODE)
218 pc->frame_start_found++;
219 if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
220 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
221 pc->frame_start_found = 0;
222 pc->state = -1;
223 return i - 3;
224 }
225 }
226 if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
227 ff_fetch_timestamp(s, i - 3, 1, i > 3);
228 }
229 }
230 }
231 pc->state = state;
232 return END_NOT_FOUND;
233 }
234
235 #define MAX_INDEX (64 - 1)
236
ff_mpeg1_decode_block_intra(GetBitContext * gb,const uint16_t * quant_matrix,uint8_t * const scantable,int last_dc[3],int16_t * block,int index,int qscale)237 int ff_mpeg1_decode_block_intra(GetBitContext *gb,
238 const uint16_t *quant_matrix,
239 uint8_t *const scantable, int last_dc[3],
240 int16_t *block, int index, int qscale)
241 {
242 int dc, diff, i = 0, component;
243 RLTable *rl = &ff_rl_mpeg1;
244
245 /* DC coefficient */
246 component = index <= 3 ? 0 : index - 4 + 1;
247
248 diff = decode_dc(gb, component);
249 if (diff >= 0xffff)
250 return AVERROR_INVALIDDATA;
251
252 dc = last_dc[component];
253 dc += diff;
254 last_dc[component] = dc;
255
256 block[0] = dc * quant_matrix[0];
257
258 {
259 OPEN_READER(re, gb);
260 UPDATE_CACHE(re, gb);
261 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
262 goto end;
263
264 /* now quantify & encode AC coefficients */
265 while (1) {
266 int level, run, j;
267
268 GET_RL_VLC(level, run, re, gb, rl->rl_vlc[0],
269 TEX_VLC_BITS, 2, 0);
270
271 if (level != 0) {
272 i += run;
273 if (i > MAX_INDEX)
274 break;
275
276 j = scantable[i];
277 level = (level * qscale * quant_matrix[j]) >> 4;
278 level = (level - 1) | 1;
279 level = (level ^ SHOW_SBITS(re, gb, 1)) -
280 SHOW_SBITS(re, gb, 1);
281 SKIP_BITS(re, gb, 1);
282 } else {
283 /* escape */
284 run = SHOW_UBITS(re, gb, 6) + 1;
285 LAST_SKIP_BITS(re, gb, 6);
286 UPDATE_CACHE(re, gb);
287 level = SHOW_SBITS(re, gb, 8);
288 SKIP_BITS(re, gb, 8);
289
290 if (level == -128) {
291 level = SHOW_UBITS(re, gb, 8) - 256;
292 SKIP_BITS(re, gb, 8);
293 } else if (level == 0) {
294 level = SHOW_UBITS(re, gb, 8);
295 SKIP_BITS(re, gb, 8);
296 }
297
298 i += run;
299 if (i > MAX_INDEX)
300 break;
301
302 j = scantable[i];
303 if (level < 0) {
304 level = -level;
305 level = (level * qscale * quant_matrix[j]) >> 4;
306 level = (level - 1) | 1;
307 level = -level;
308 } else {
309 level = (level * qscale * quant_matrix[j]) >> 4;
310 level = (level - 1) | 1;
311 }
312 }
313
314 block[j] = level;
315 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
316 break;
317
318 UPDATE_CACHE(re, gb);
319 }
320 end:
321 LAST_SKIP_BITS(re, gb, 2);
322 CLOSE_READER(re, gb);
323 }
324
325 if (i > MAX_INDEX)
326 i = AVERROR_INVALIDDATA;
327
328 return i;
329 }
330