FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/mpeg12.c
Date: 2022-07-04 00:18:54
Exec Total Coverage
Lines: 134 143 93.7%
Branches: 69 78 88.5%

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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/thread.h"
33
34 #include "avcodec.h"
35 #include "mpegvideo.h"
36 #include "mpeg12.h"
37 #include "mpeg12data.h"
38 #include "mpeg12dec.h"
39 #include "mpegvideodata.h"
40 #include "startcode.h"
41
42 static const uint8_t table_mb_ptype[7][2] = {
43 { 3, 5 }, // 0x01 MB_INTRA
44 { 1, 2 }, // 0x02 MB_PAT
45 { 1, 3 }, // 0x08 MB_FOR
46 { 1, 1 }, // 0x0A MB_FOR|MB_PAT
47 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
48 { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
49 { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
50 };
51
52 static const uint8_t table_mb_btype[11][2] = {
53 { 3, 5 }, // 0x01 MB_INTRA
54 { 2, 3 }, // 0x04 MB_BACK
55 { 3, 3 }, // 0x06 MB_BACK|MB_PAT
56 { 2, 4 }, // 0x08 MB_FOR
57 { 3, 4 }, // 0x0A MB_FOR|MB_PAT
58 { 2, 2 }, // 0x0C MB_FOR|MB_BACK
59 { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
60 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
61 { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
62 { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
63 { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
64 };
65
66 250 av_cold void ff_init_2d_vlc_rl(RLTable *rl, unsigned static_size, int flags)
67 {
68 int i;
69 250 VLCElem table[680] = { 0 };
70 250 VLC vlc = { .table = table, .table_allocated = static_size };
71
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250 av_assert0(static_size <= FF_ARRAY_ELEMS(table));
72 250 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);
73
74
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169494 for (i = 0; i < vlc.table_size; i++) {
75 169244 int code = vlc.table[i].sym;
76 169244 int len = vlc.table[i].len;
77 int level, run;
78
79
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169244 if (len == 0) { // illegal code
80 5240 run = 65;
81 5240 level = MAX_LEVEL;
82
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164004 } else if (len<0) { //more bits needed
83 1622 run = 0;
84 1622 level = code;
85 } else {
86
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162382 if (code == rl->n) { //esc
87 2000 run = 65;
88 2000 level = 0;
89
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160382 } else if (code == rl->n+1) { //eob
90 19904 run = 0;
91 19904 level = 127;
92 } else {
93 140478 run = rl->table_run [code] + 1;
94 140478 level = rl->table_level[code];
95 }
96 }
97 169244 rl->rl_vlc[0][i].len = len;
98 169244 rl->rl_vlc[0][i].level = level;
99 169244 rl->rl_vlc[0][i].run = run;
100 }
101 250 }
102
103 314 av_cold void ff_mpeg12_common_init(MpegEncContext *s)
104 {
105
106 314 s->y_dc_scale_table =
107 314 s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];
108
109 314 }
110
111 403733 void ff_mpeg1_clean_buffers(MpegEncContext *s)
112 {
113 403733 s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
114 403733 s->last_dc[1] = s->last_dc[0];
115 403733 s->last_dc[2] = s->last_dc[0];
116 403733 memset(s->last_mv, 0, sizeof(s->last_mv));
117 403733 }
118
119
120 /******************************************/
121 /* decoding */
122
123 VLC ff_mv_vlc;
124
125 VLC ff_dc_lum_vlc;
126 VLC ff_dc_chroma_vlc;
127
128 VLC ff_mbincr_vlc;
129 VLC ff_mb_ptype_vlc;
130 VLC ff_mb_btype_vlc;
131 VLC ff_mb_pat_vlc;
132
133 124 static av_cold void mpeg12_init_vlcs(void)
134 {
135 124 INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
136 ff_mpeg12_vlc_dc_lum_bits, 1, 1,
137 ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
138 124 INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,
139 ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
140 ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
141 124 INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
142 &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
143 &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 266);
144 124 INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
145 &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
146 &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
147 124 INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
148 &ff_mpeg12_mbPatTable[0][1], 2, 1,
149 &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);
150
151 124 INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
152 &table_mb_ptype[0][1], 2, 1,
153 &table_mb_ptype[0][0], 2, 1, 64);
154 124 INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
155 &table_mb_btype[0][1], 2, 1,
156 &table_mb_btype[0][0], 2, 1, 64);
157
158 124 INIT_2D_VLC_RL(ff_rl_mpeg1, 680, 0);
159 124 INIT_2D_VLC_RL(ff_rl_mpeg2, 674, 0);
160 124 }
161
162 278 av_cold void ff_mpeg12_init_vlcs(void)
163 {
164 static AVOnce init_static_once = AV_ONCE_INIT;
165 278 ff_thread_once(&init_static_once, mpeg12_init_vlcs);
166 278 }
167
168 #if FF_API_FLAG_TRUNCATED
169 /**
170 * Find the end of the current frame in the bitstream.
171 * @return the position of the first byte of the next frame, or -1
172 */
173 44434 int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
174 {
175 int i;
176 44434 uint32_t state = pc->state;
177
178 /* EOF considered as end of frame */
179
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44434 if (buf_size == 0)
180 312 return 0;
181
182 /*
183 0 frame start -> 1/4
184 1 first_SEQEXT -> 0/2
185 2 first field start -> 3/0
186 3 second_SEQEXT -> 2/0
187 4 searching end
188 */
189
190
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258267 for (i = 0; i < buf_size; i++) {
191 av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
192
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220131 if (pc->frame_start_found & 1) {
193
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22685 if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
194 1784 pc->frame_start_found--;
195
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20901 else if (state == EXT_START_CODE + 2) {
196
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6967 if ((buf[i] & 3) == 3)
197 3968 pc->frame_start_found = 0;
198 else
199 2999 pc->frame_start_found = (pc->frame_start_found + 1) & 3;
200 }
201 22685 state++;
202 } else {
203 197446 i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
204
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197446 if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
205 6415 i++;
206 6415 pc->frame_start_found = 4;
207 }
208
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197446 if (state == SEQ_END_CODE) {
209 10 pc->frame_start_found = 0;
210 10 pc->state=-1;
211 10 return i+1;
212 }
213
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197436 if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
214 pc->frame_start_found = 0;
215
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197436 if (pc->frame_start_found < 4 && state == EXT_START_CODE)
216 8751 pc->frame_start_found++;
217
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197436 if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
218
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120651 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
219 5976 pc->frame_start_found = 0;
220 5976 pc->state = -1;
221 5976 return i - 3;
222 }
223 }
224
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191460 if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
225 6405 ff_fetch_timestamp(s, i - 3, 1, i > 3);
226 }
227 }
228 }
229 38136 pc->state = state;
230 38136 return END_NOT_FOUND;
231 }
232 #endif
233
234 #define MAX_INDEX (64 - 1)
235
236 176526 int ff_mpeg1_decode_block_intra(GetBitContext *gb,
237 const uint16_t *quant_matrix,
238 const uint8_t *scantable, int last_dc[3],
239 int16_t *block, int index, int qscale)
240 {
241 176526 int dc, diff, i = 0, component;
242 176526 RLTable *rl = &ff_rl_mpeg1;
243
244 /* DC coefficient */
245 176526 component = index <= 3 ? 0 : index - 4 + 1;
246
247 176526 diff = decode_dc(gb, component);
248
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176526 if (diff >= 0xffff)
249 return AVERROR_INVALIDDATA;
250
251 176526 dc = last_dc[component];
252 176526 dc += diff;
253 176526 last_dc[component] = dc;
254
255 176526 block[0] = dc * quant_matrix[0];
256
257 {
258 176526 OPEN_READER(re, gb);
259 176526 UPDATE_CACHE(re, gb);
260
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176526 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
261 36372 goto end;
262
263 /* now quantify & encode AC coefficients */
264 1334388 while (1) {
265 int level, run, j;
266
267
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1474542 GET_RL_VLC(level, run, re, gb, rl->rl_vlc[0],
268 TEX_VLC_BITS, 2, 0);
269
270
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1474542 if (level != 0) {
271 1469278 i += run;
272
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1469278 if (i > MAX_INDEX)
273 break;
274
275 1469278 j = scantable[i];
276 1469278 level = (level * qscale * quant_matrix[j]) >> 4;
277 1469278 level = (level - 1) | 1;
278 1469278 level = (level ^ SHOW_SBITS(re, gb, 1)) -
279 1469278 SHOW_SBITS(re, gb, 1);
280 1469278 SKIP_BITS(re, gb, 1);
281 } else {
282 /* escape */
283 5264 run = SHOW_UBITS(re, gb, 6) + 1;
284 5264 LAST_SKIP_BITS(re, gb, 6);
285 5264 UPDATE_CACHE(re, gb);
286 5264 level = SHOW_SBITS(re, gb, 8);
287 5264 SKIP_BITS(re, gb, 8);
288
289
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5264 if (level == -128) {
290 level = SHOW_UBITS(re, gb, 8) - 256;
291 SKIP_BITS(re, gb, 8);
292
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5264 } else if (level == 0) {
293 level = SHOW_UBITS(re, gb, 8);
294 SKIP_BITS(re, gb, 8);
295 }
296
297 5264 i += run;
298
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5264 if (i > MAX_INDEX)
299 break;
300
301 5264 j = scantable[i];
302
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5264 if (level < 0) {
303 2967 level = -level;
304 2967 level = (level * qscale * quant_matrix[j]) >> 4;
305 2967 level = (level - 1) | 1;
306 2967 level = -level;
307 } else {
308 2297 level = (level * qscale * quant_matrix[j]) >> 4;
309 2297 level = (level - 1) | 1;
310 }
311 }
312
313 1474542 block[j] = level;
314
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1474542 if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
315 140154 break;
316
317 1334388 UPDATE_CACHE(re, gb);
318 }
319 176526 end:
320 176526 LAST_SKIP_BITS(re, gb, 2);
321 176526 CLOSE_READER(re, gb);
322 }
323
324
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176526 if (i > MAX_INDEX)
325 i = AVERROR_INVALIDDATA;
326
327 176526 return i;
328 }
329