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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 "mpegvideo.h"
37#include "error_resilience.h"
38#include "mpeg12.h"
39#include "mpeg12data.h"
40#include "mpegvideodata.h"
41#include "bytestream.h"
42#include "thread.h"
43
44uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];
45
46static const uint8_t table_mb_ptype[7][2] = {
47 { 3, 5 }, // 0x01 MB_INTRA
48 { 1, 2 }, // 0x02 MB_PAT
49 { 1, 3 }, // 0x08 MB_FOR
50 { 1, 1 }, // 0x0A MB_FOR|MB_PAT
51 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
52 { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
53 { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
54};
55
56static const uint8_t table_mb_btype[11][2] = {
57 { 3, 5 }, // 0x01 MB_INTRA
58 { 2, 3 }, // 0x04 MB_BACK
59 { 3, 3 }, // 0x06 MB_BACK|MB_PAT
60 { 2, 4 }, // 0x08 MB_FOR
61 { 3, 4 }, // 0x0A MB_FOR|MB_PAT
62 { 2, 2 }, // 0x0C MB_FOR|MB_BACK
63 { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
64 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
65 { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
66 { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
67 { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
68};
69
70av_cold void ff_init_2d_vlc_rl(RLTable *rl, unsigned static_size, int flags)
71{
72 int i;
73 VLC_TYPE table[680][2] = {{0}};
74 VLC vlc = { .table = table, .table_allocated = static_size };
75 av_assert0(static_size <= FF_ARRAY_ELEMS(table));
76 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);
77
78 for (i = 0; i < vlc.table_size; i++) {
79 int code = vlc.table[i][0];
80 int len = vlc.table[i][1];
81 int level, run;
82
83 if (len == 0) { // illegal code
84 run = 65;
85 level = MAX_LEVEL;
86 } else if (len<0) { //more bits needed
87 run = 0;
88 level = code;
89 } else {
90 if (code == rl->n) { //esc
91 run = 65;
92 level = 0;
93 } else if (code == rl->n+1) { //eob
94 run = 0;
95 level = 127;
96 } else {
97 run = rl->table_run [code] + 1;
98 level = rl->table_level[code];
99 }
100 }
101 rl->rl_vlc[0][i].len = len;
102 rl->rl_vlc[0][i].level = level;
103 rl->rl_vlc[0][i].run = run;
104 }
105}
106
107av_cold void ff_mpeg12_common_init(MpegEncContext *s)
108{
109
110 s->y_dc_scale_table =
111 s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
112
113}
114
115void ff_mpeg1_clean_buffers(MpegEncContext *s)
116{
117 s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
118 s->last_dc[1] = s->last_dc[0];
119 s->last_dc[2] = s->last_dc[0];
120 memset(s->last_mv, 0, sizeof(s->last_mv));
121}
122
123
124/******************************************/
125/* decoding */
126
127VLC ff_mv_vlc;
128
129VLC ff_dc_lum_vlc;
130VLC ff_dc_chroma_vlc;
131
132VLC ff_mbincr_vlc;
133VLC ff_mb_ptype_vlc;
134VLC ff_mb_btype_vlc;
135VLC ff_mb_pat_vlc;
136
137av_cold void ff_mpeg12_init_vlcs(void)
138{
139 static int done = 0;
140
141 if (!done) {
142 done = 1;
143
144 INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
145 ff_mpeg12_vlc_dc_lum_bits, 1, 1,
146 ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
147 INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,
148 ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
149 ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
150 INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
151 &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
152 &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
153 INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
154 &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
155 &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
156 INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
157 &ff_mpeg12_mbPatTable[0][1], 2, 1,
158 &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
159
160 INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
161 &table_mb_ptype[0][1], 2, 1,
162 &table_mb_ptype[0][0], 2, 1, 64);
163 INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
164 &table_mb_btype[0][1], 2, 1,
165 &table_mb_btype[0][0], 2, 1, 64);
166 ff_rl_init(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
167 ff_rl_init(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);
168
169 INIT_2D_VLC_RL(ff_rl_mpeg1, 680, 0);
170 INIT_2D_VLC_RL(ff_rl_mpeg2, 674, 0);
171 }
172}
173
174/**
175 * Find the end of the current frame in the bitstream.
176 * @return the position of the first byte of the next frame, or -1
177 */
178int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
179{
180 int i;
181 uint32_t state = pc->state;
182
183 /* EOF considered as end of frame */
184 if (buf_size == 0)
185 return 0;
186
187/*
188 0 frame start -> 1/4
189 1 first_SEQEXT -> 0/2
190 2 first field start -> 3/0
191 3 second_SEQEXT -> 2/0
192 4 searching end
193*/
194
195 for (i = 0; i < buf_size; i++) {
196 av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
197 if (pc->frame_start_found & 1) {
198 if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
199 pc->frame_start_found--;
200 else if (state == EXT_START_CODE + 2) {
201 if ((buf[i] & 3) == 3)
202 pc->frame_start_found = 0;
203 else
204 pc->frame_start_found = (pc->frame_start_found + 1) & 3;
205 }
206 state++;
207 } else {
208 i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
209 if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
210 i++;
211 pc->frame_start_found = 4;
212 }
213 if (state == SEQ_END_CODE) {
214 pc->frame_start_found = 0;
215 pc->state=-1;
216 return i+1;
217 }
218 if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
219 pc->frame_start_found = 0;
220 if (pc->frame_start_found < 4 && state == EXT_START_CODE)
221 pc->frame_start_found++;
222 if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
223 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
224 pc->frame_start_found = 0;
225 pc->state = -1;
226 return i - 3;
227 }
228 }
229 if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
230 ff_fetch_timestamp(s, i - 3, 1, i > 3);
231 }
232 }
233 }
234 pc->state = state;
235 return END_NOT_FOUND;
236}
237
238#define MAX_INDEX (64 - 1)
239
240int ff_mpeg1_decode_block_intra(GetBitContext *gb,
241 const uint16_t *quant_matrix,
242 uint8_t *const scantable, int last_dc[3],
243 int16_t *block, int index, int qscale)
244{
245 int dc, diff, i = 0, component;
246 RLTable *rl = &ff_rl_mpeg1;
247
248 /* DC coefficient */
249 component = index <= 3 ? 0 : index - 4 + 1;
250
251 diff = decode_dc(gb, component);
252 if (diff >= 0xffff)
253 return AVERROR_INVALIDDATA;
254
255 dc = last_dc[component];
256 dc += diff;
257 last_dc[component] = dc;
258
259 block[0] = dc * quant_matrix[0];
260
261 {
262 OPEN_READER(re, gb);
263 UPDATE_CACHE(re, gb);
264 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
265 goto end;
266
267 /* now quantify & encode AC coefficients */
268 while (1) {
269 int level, run, j;
270
271 GET_RL_VLC(level, run, re, gb, rl->rl_vlc[0],
272 TEX_VLC_BITS, 2, 0);
273
274 if (level != 0) {
275 i += run;
276 if (i > MAX_INDEX)
277 break;
278
279 j = scantable[i];
280 level = (level * qscale * quant_matrix[j]) >> 4;
281 level = (level - 1) | 1;
282 level = (level ^ SHOW_SBITS(re, gb, 1)) -
283 SHOW_SBITS(re, gb, 1);
284 SKIP_BITS(re, gb, 1);
285 } else {
286 /* escape */
287 run = SHOW_UBITS(re, gb, 6) + 1;
288 LAST_SKIP_BITS(re, gb, 6);
289 UPDATE_CACHE(re, gb);
290 level = SHOW_SBITS(re, gb, 8);
291 SKIP_BITS(re, gb, 8);
292
293 if (level == -128) {
294 level = SHOW_UBITS(re, gb, 8) - 256;
295 SKIP_BITS(re, gb, 8);
296 } else if (level == 0) {
297 level = SHOW_UBITS(re, gb, 8);
298 SKIP_BITS(re, gb, 8);
299 }
300
301 i += run;
302 if (i > MAX_INDEX)
303 break;
304
305 j = scantable[i];
306 if (level < 0) {
307 level = -level;
308 level = (level * qscale * quant_matrix[j]) >> 4;
309 level = (level - 1) | 1;
310 level = -level;
311 } else {
312 level = (level * qscale * quant_matrix[j]) >> 4;
313 level = (level - 1) | 1;
314 }
315 }
316
317 block[j] = level;
318 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
319 break;
320
321 UPDATE_CACHE(re, gb);
322 }
323end:
324 LAST_SKIP_BITS(re, gb, 2);
325 CLOSE_READER(re, gb);
326 }
327
328 if (i > MAX_INDEX)
329 i = AVERROR_INVALIDDATA;
330
331 return i;
332}
333
generated by cgit at 2024-05-17 18:35:29 (GMT)