FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/dirac_parser.c
Date: 2025-12-16 02:06:53
Exec Total Coverage
Lines: 115 127 90.6%
Functions: 5 5 100.0%
Branches: 64 90 71.1%
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1 /*
2 * Dirac parser
3 *
4 * Copyright (c) 2007-2008 Marco Gerards <marco@gnu.org>
5 * Copyright (c) 2008 BBC, Anuradha Suraparaju <asuraparaju@gmail.com>
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 /**
25 * @file
26 * Dirac Parser
27 * @author Marco Gerards <marco@gnu.org>
28 */
29
30 #include <string.h>
31
32 #include "libavutil/attributes.h"
33 #include "libavutil/intreadwrite.h"
34 #include "libavutil/mem.h"
35
36 #include "avcodec.h"
37 #include "parser_internal.h"
38
39 #define DIRAC_PARSE_INFO_PREFIX 0x42424344
40
41 /**
42 * Find the end of the current frame in the bitstream.
43 * @return the position of the first byte of the next frame or -1
44 */
45 typedef struct DiracParseContext {
46 int state;
47 int is_synced;
48 int sync_offset;
49 int header_bytes_needed;
50 int overread_index;
51 int buffer_size;
52 int index;
53 uint8_t *buffer;
54 int dirac_unit_size;
55 uint8_t *dirac_unit;
56 } DiracParseContext;
57
58 812 static int find_frame_end(DiracParseContext *pc,
59 const uint8_t *buf, int buf_size)
60 {
61 812 uint32_t state = pc->state;
62 812 int i = 0;
63
64
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 812 if (!pc->is_synced) {
65
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 8 for (i = 0; i < buf_size; i++) {
66 8 state = (state << 8) | buf[i];
67
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 8 if (state == DIRAC_PARSE_INFO_PREFIX) {
68 2 state = -1;
69 2 pc->is_synced = 1;
70 2 pc->header_bytes_needed = 9;
71 2 pc->sync_offset = i;
72 2 break;
73 }
74 }
75 }
76
77
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 812 if (pc->is_synced) {
78 812 pc->sync_offset = 0;
79
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 670134 for (; i < buf_size; i++) {
80
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 669478 if (state == DIRAC_PARSE_INFO_PREFIX) {
81
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 156 if ((buf_size - i) >= pc->header_bytes_needed) {
82 154 pc->state = -1;
83 154 return i + pc->header_bytes_needed;
84 } else {
85 2 pc->header_bytes_needed = 9 - (buf_size - i);
86 2 break;
87 }
88 } else
89 669322 state = (state << 8) | buf[i];
90 }
91 }
92 658 pc->state = state;
93 658 return -1;
94 }
95
96 typedef struct DiracParseUnit {
97 int next_pu_offset;
98 int prev_pu_offset;
99 uint8_t pu_type;
100 } DiracParseUnit;
101
102 308 static int unpack_parse_unit(DiracParseUnit *pu, DiracParseContext *pc,
103 int offset)
104 {
105 int i;
106 int8_t *start;
107 static const uint8_t valid_pu_types[] = {
108 0x00, 0x10, 0x20, 0x30, 0x08, 0x48, 0xC8, 0xE8, 0x0A, 0x0C, 0x0D, 0x0E,
109 0x4C, 0x09, 0xCC, 0x88, 0xCB
110 };
111
112
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 308 if (offset < 0 || pc->index - 13 < offset)
113 ✗ return 0;
114
115 308 start = pc->buffer + offset;
116 308 pu->pu_type = start[4];
117
118 308 pu->next_pu_offset = AV_RB32(start + 5);
119 308 pu->prev_pu_offset = AV_RB32(start + 9);
120
121 /* Check for valid parse code */
122
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 1990 for (i = 0; i < 17; i++)
123
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 1990 if (valid_pu_types[i] == pu->pu_type)
124 308 break;
125
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 308 if (i == 17)
126 ✗ return 0;
127
128
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 308 if (pu->pu_type == 0x10 && pu->next_pu_offset == 0x00)
129 2 pu->next_pu_offset = 13; /* The length of a parse info header */
130
131 /* Check if the parse offsets are somewhat sane */
132
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 308 if ((pu->next_pu_offset && pu->next_pu_offset < 13) ||
133
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 308 (pu->prev_pu_offset && pu->prev_pu_offset < 13))
134 ✗ return 0;
135
136 308 return 1;
137 }
138
139 812 static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx,
140 int next, const uint8_t **buf, int *buf_size)
141 {
142
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 1624 int parse_timing_info = (s->pts == AV_NOPTS_VALUE &&
143
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 812 s->dts == AV_NOPTS_VALUE);
144 812 DiracParseContext *pc = s->priv_data;
145
146
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 812 if (pc->overread_index) {
147 60 memmove(pc->buffer, pc->buffer + pc->overread_index,
148 60 pc->index - pc->overread_index);
149 60 pc->index -= pc->overread_index;
150 60 pc->overread_index = 0;
151
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 60 if (*buf_size == 0 && pc->buffer[4] == 0x10) {
152 2 *buf = pc->buffer;
153 2 *buf_size = pc->index;
154 2 return 0;
155 }
156 }
157
158
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 810 if (next == -1) {
159 /* Found a possible frame start but not a frame end */
160 void *new_buffer =
161 656 av_fast_realloc(pc->buffer, &pc->buffer_size,
162 656 pc->index + (*buf_size - pc->sync_offset));
163
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 656 if (!new_buffer)
164 ✗ return AVERROR(ENOMEM);
165 656 pc->buffer = new_buffer;
166 656 memcpy(pc->buffer + pc->index, (*buf + pc->sync_offset),
167 656 *buf_size - pc->sync_offset);
168 656 pc->index += *buf_size - pc->sync_offset;
169 656 return -1;
170 } else {
171 /* Found a possible frame start and a possible frame end */
172 DiracParseUnit pu1, pu;
173 154 void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
174 154 pc->index + next);
175
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 154 if (!new_buffer)
176 94 return AVERROR(ENOMEM);
177 154 pc->buffer = new_buffer;
178 154 memcpy(pc->buffer + pc->index, *buf, next);
179 154 pc->index += next;
180
181 /* Need to check if we have a valid Parse Unit. We can't go by the
182 * sync pattern 'BBCD' alone because arithmetic coding of the residual
183 * and motion data can cause the pattern triggering a false start of
184 * frame. So check if the previous parse offset of the next parse unit
185 * is equal to the next parse offset of the current parse unit then
186 * we can be pretty sure that we have a valid parse unit */
187
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 308 if (!unpack_parse_unit(&pu1, pc, pc->index - 13) ||
188 154 !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) ||
189
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 154 pu.next_pu_offset != pu1.prev_pu_offset ||
190
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 154 pc->index < pc->dirac_unit_size + 13LL + pu1.prev_pu_offset
191 ) {
192 ✗ pc->index -= 9;
193 ✗ *buf_size = next - 9;
194 ✗ pc->header_bytes_needed = 9;
195 ✗ return -1;
196 }
197
198 /* All non-frame data must be accompanied by frame data. This is to
199 * ensure that pts is set correctly. So if the current parse unit is
200 * not frame data, wait for frame data to come along */
201
202 154 pc->dirac_unit = pc->buffer + pc->index - 13 -
203 154 pu1.prev_pu_offset - pc->dirac_unit_size;
204
205 154 pc->dirac_unit_size += pu.next_pu_offset;
206
207
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 154 if ((pu.pu_type & 0x08) != 0x08) {
208 94 pc->header_bytes_needed = 9;
209 94 *buf_size = next;
210 94 return -1;
211 }
212
213 /* Get the picture number to set the pts and dts*/
214
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 60 if (parse_timing_info && pu1.prev_pu_offset >= 13) {
215 60 uint8_t *cur_pu = pc->buffer +
216 60 pc->index - 13 - pu1.prev_pu_offset;
217 60 int64_t pts = AV_RB32(cur_pu + 13);
218
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 60 if (s->last_pts == 0 && s->last_dts == 0)
219 2 s->dts = pts - 1;
220
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 58 else if (s->last_dts != AV_NOPTS_VALUE)
221 58 s->dts = s->last_dts + 1;
222 60 s->pts = pts;
223
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 60 if (!avctx->has_b_frames && (cur_pu[4] & 0x03))
224 1 avctx->has_b_frames = 1;
225 }
226
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 60 if (avctx->has_b_frames && s->pts == s->dts)
227 21 s->pict_type = AV_PICTURE_TYPE_B;
228
229 /* Finally have a complete Dirac data unit */
230 60 *buf = pc->dirac_unit;
231 60 *buf_size = pc->dirac_unit_size;
232
233 60 pc->dirac_unit_size = 0;
234 60 pc->overread_index = pc->index - 13;
235 60 pc->header_bytes_needed = 9;
236 }
237 60 return next;
238 }
239
240 812 static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
241 const uint8_t **poutbuf, int *poutbuf_size,
242 const uint8_t *buf, int buf_size)
243 {
244 812 DiracParseContext *pc = s->priv_data;
245 int next;
246
247 812 *poutbuf = NULL;
248 812 *poutbuf_size = 0;
249
250
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 812 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
251 ✗ next = buf_size;
252 ✗ *poutbuf = buf;
253 ✗ *poutbuf_size = buf_size;
254 /* Assume that data has been packetized into an encapsulation unit. */
255 } else {
256 812 next = find_frame_end(pc, buf, buf_size);
257
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 812 if (!pc->is_synced && next == -1)
258 /* No frame start found yet. So throw away the entire buffer. */
259 ✗ return buf_size;
260
261
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 812 if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0)
262 750 return buf_size;
263 }
264
265 62 *poutbuf = buf;
266 62 *poutbuf_size = buf_size;
267 62 return next;
268 }
269
270 35 static av_cold void dirac_parse_close(AVCodecParserContext *s)
271 {
272 35 DiracParseContext *pc = s->priv_data;
273
274
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 35 if (pc->buffer_size > 0)
275 2 av_freep(&pc->buffer);
276 35 }
277
278 const FFCodecParser ff_dirac_parser = {
279 PARSER_CODEC_LIST(AV_CODEC_ID_DIRAC),
280 .priv_data_size = sizeof(DiracParseContext),
281 .parse = dirac_parse,
282 .close = dirac_parse_close,
283 };
284