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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 | |||
38 | #define DIRAC_PARSE_INFO_PREFIX 0x42424344 | ||
39 | |||
40 | /** | ||
41 | * Find the end of the current frame in the bitstream. | ||
42 | * @return the position of the first byte of the next frame or -1 | ||
43 | */ | ||
44 | typedef struct DiracParseContext { | ||
45 | int state; | ||
46 | int is_synced; | ||
47 | int sync_offset; | ||
48 | int header_bytes_needed; | ||
49 | int overread_index; | ||
50 | int buffer_size; | ||
51 | int index; | ||
52 | uint8_t *buffer; | ||
53 | int dirac_unit_size; | ||
54 | uint8_t *dirac_unit; | ||
55 | } DiracParseContext; | ||
56 | |||
57 | 812 | static int find_frame_end(DiracParseContext *pc, | |
58 | const uint8_t *buf, int buf_size) | ||
59 | { | ||
60 | 812 | uint32_t state = pc->state; | |
61 | 812 | int i = 0; | |
62 | |||
63 |
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812 | if (!pc->is_synced) { |
64 |
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8 | for (i = 0; i < buf_size; i++) { |
65 | 8 | state = (state << 8) | buf[i]; | |
66 |
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8 | if (state == DIRAC_PARSE_INFO_PREFIX) { |
67 | 2 | state = -1; | |
68 | 2 | pc->is_synced = 1; | |
69 | 2 | pc->header_bytes_needed = 9; | |
70 | 2 | pc->sync_offset = i; | |
71 | 2 | break; | |
72 | } | ||
73 | } | ||
74 | } | ||
75 | |||
76 |
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812 | if (pc->is_synced) { |
77 | 812 | pc->sync_offset = 0; | |
78 |
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670134 | for (; i < buf_size; i++) { |
79 |
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669478 | if (state == DIRAC_PARSE_INFO_PREFIX) { |
80 |
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156 | if ((buf_size - i) >= pc->header_bytes_needed) { |
81 | 154 | pc->state = -1; | |
82 | 154 | return i + pc->header_bytes_needed; | |
83 | } else { | ||
84 | 2 | pc->header_bytes_needed = 9 - (buf_size - i); | |
85 | 2 | break; | |
86 | } | ||
87 | } else | ||
88 | 669322 | state = (state << 8) | buf[i]; | |
89 | } | ||
90 | } | ||
91 | 658 | pc->state = state; | |
92 | 658 | return -1; | |
93 | } | ||
94 | |||
95 | typedef struct DiracParseUnit { | ||
96 | int next_pu_offset; | ||
97 | int prev_pu_offset; | ||
98 | uint8_t pu_type; | ||
99 | } DiracParseUnit; | ||
100 | |||
101 | 308 | static int unpack_parse_unit(DiracParseUnit *pu, DiracParseContext *pc, | |
102 | int offset) | ||
103 | { | ||
104 | int i; | ||
105 | int8_t *start; | ||
106 | static const uint8_t valid_pu_types[] = { | ||
107 | 0x00, 0x10, 0x20, 0x30, 0x08, 0x48, 0xC8, 0xE8, 0x0A, 0x0C, 0x0D, 0x0E, | ||
108 | 0x4C, 0x09, 0xCC, 0x88, 0xCB | ||
109 | }; | ||
110 | |||
111 |
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308 | if (offset < 0 || pc->index - 13 < offset) |
112 | ✗ | return 0; | |
113 | |||
114 | 308 | start = pc->buffer + offset; | |
115 | 308 | pu->pu_type = start[4]; | |
116 | |||
117 | 308 | pu->next_pu_offset = AV_RB32(start + 5); | |
118 | 308 | pu->prev_pu_offset = AV_RB32(start + 9); | |
119 | |||
120 | /* Check for valid parse code */ | ||
121 |
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1990 | for (i = 0; i < 17; i++) |
122 |
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1990 | if (valid_pu_types[i] == pu->pu_type) |
123 | 308 | break; | |
124 |
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308 | if (i == 17) |
125 | ✗ | return 0; | |
126 | |||
127 |
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308 | if (pu->pu_type == 0x10 && pu->next_pu_offset == 0x00) |
128 | 2 | pu->next_pu_offset = 13; /* The length of a parse info header */ | |
129 | |||
130 | /* Check if the parse offsets are somewhat sane */ | ||
131 |
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308 | if ((pu->next_pu_offset && pu->next_pu_offset < 13) || |
132 |
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308 | (pu->prev_pu_offset && pu->prev_pu_offset < 13)) |
133 | ✗ | return 0; | |
134 | |||
135 | 308 | return 1; | |
136 | } | ||
137 | |||
138 | 812 | static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx, | |
139 | int next, const uint8_t **buf, int *buf_size) | ||
140 | { | ||
141 |
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1624 | int parse_timing_info = (s->pts == AV_NOPTS_VALUE && |
142 |
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812 | s->dts == AV_NOPTS_VALUE); |
143 | 812 | DiracParseContext *pc = s->priv_data; | |
144 | |||
145 |
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812 | if (pc->overread_index) { |
146 | 60 | memmove(pc->buffer, pc->buffer + pc->overread_index, | |
147 | 60 | pc->index - pc->overread_index); | |
148 | 60 | pc->index -= pc->overread_index; | |
149 | 60 | pc->overread_index = 0; | |
150 |
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60 | if (*buf_size == 0 && pc->buffer[4] == 0x10) { |
151 | 2 | *buf = pc->buffer; | |
152 | 2 | *buf_size = pc->index; | |
153 | 2 | return 0; | |
154 | } | ||
155 | } | ||
156 | |||
157 |
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810 | if (next == -1) { |
158 | /* Found a possible frame start but not a frame end */ | ||
159 | void *new_buffer = | ||
160 | 656 | av_fast_realloc(pc->buffer, &pc->buffer_size, | |
161 | 656 | pc->index + (*buf_size - pc->sync_offset)); | |
162 |
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656 | if (!new_buffer) |
163 | ✗ | return AVERROR(ENOMEM); | |
164 | 656 | pc->buffer = new_buffer; | |
165 | 656 | memcpy(pc->buffer + pc->index, (*buf + pc->sync_offset), | |
166 | 656 | *buf_size - pc->sync_offset); | |
167 | 656 | pc->index += *buf_size - pc->sync_offset; | |
168 | 656 | return -1; | |
169 | } else { | ||
170 | /* Found a possible frame start and a possible frame end */ | ||
171 | DiracParseUnit pu1, pu; | ||
172 | 154 | void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, | |
173 | 154 | pc->index + next); | |
174 |
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154 | if (!new_buffer) |
175 | 94 | return AVERROR(ENOMEM); | |
176 | 154 | pc->buffer = new_buffer; | |
177 | 154 | memcpy(pc->buffer + pc->index, *buf, next); | |
178 | 154 | pc->index += next; | |
179 | |||
180 | /* Need to check if we have a valid Parse Unit. We can't go by the | ||
181 | * sync pattern 'BBCD' alone because arithmetic coding of the residual | ||
182 | * and motion data can cause the pattern triggering a false start of | ||
183 | * frame. So check if the previous parse offset of the next parse unit | ||
184 | * is equal to the next parse offset of the current parse unit then | ||
185 | * we can be pretty sure that we have a valid parse unit */ | ||
186 |
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308 | if (!unpack_parse_unit(&pu1, pc, pc->index - 13) || |
187 | 154 | !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) || | |
188 |
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154 | pu.next_pu_offset != pu1.prev_pu_offset || |
189 |
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154 | pc->index < pc->dirac_unit_size + 13LL + pu1.prev_pu_offset |
190 | ) { | ||
191 | ✗ | pc->index -= 9; | |
192 | ✗ | *buf_size = next - 9; | |
193 | ✗ | pc->header_bytes_needed = 9; | |
194 | ✗ | return -1; | |
195 | } | ||
196 | |||
197 | /* All non-frame data must be accompanied by frame data. This is to | ||
198 | * ensure that pts is set correctly. So if the current parse unit is | ||
199 | * not frame data, wait for frame data to come along */ | ||
200 | |||
201 | 154 | pc->dirac_unit = pc->buffer + pc->index - 13 - | |
202 | 154 | pu1.prev_pu_offset - pc->dirac_unit_size; | |
203 | |||
204 | 154 | pc->dirac_unit_size += pu.next_pu_offset; | |
205 | |||
206 |
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154 | if ((pu.pu_type & 0x08) != 0x08) { |
207 | 94 | pc->header_bytes_needed = 9; | |
208 | 94 | *buf_size = next; | |
209 | 94 | return -1; | |
210 | } | ||
211 | |||
212 | /* Get the picture number to set the pts and dts*/ | ||
213 |
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60 | if (parse_timing_info && pu1.prev_pu_offset >= 13) { |
214 | 60 | uint8_t *cur_pu = pc->buffer + | |
215 | 60 | pc->index - 13 - pu1.prev_pu_offset; | |
216 | 60 | int64_t pts = AV_RB32(cur_pu + 13); | |
217 |
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60 | if (s->last_pts == 0 && s->last_dts == 0) |
218 | 2 | s->dts = pts - 1; | |
219 |
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58 | else if (s->last_dts != AV_NOPTS_VALUE) |
220 | 58 | s->dts = s->last_dts + 1; | |
221 | 60 | s->pts = pts; | |
222 |
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60 | if (!avctx->has_b_frames && (cur_pu[4] & 0x03)) |
223 | 1 | avctx->has_b_frames = 1; | |
224 | } | ||
225 |
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60 | if (avctx->has_b_frames && s->pts == s->dts) |
226 | 21 | s->pict_type = AV_PICTURE_TYPE_B; | |
227 | |||
228 | /* Finally have a complete Dirac data unit */ | ||
229 | 60 | *buf = pc->dirac_unit; | |
230 | 60 | *buf_size = pc->dirac_unit_size; | |
231 | |||
232 | 60 | pc->dirac_unit_size = 0; | |
233 | 60 | pc->overread_index = pc->index - 13; | |
234 | 60 | pc->header_bytes_needed = 9; | |
235 | } | ||
236 | 60 | return next; | |
237 | } | ||
238 | |||
239 | 812 | static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx, | |
240 | const uint8_t **poutbuf, int *poutbuf_size, | ||
241 | const uint8_t *buf, int buf_size) | ||
242 | { | ||
243 | 812 | DiracParseContext *pc = s->priv_data; | |
244 | int next; | ||
245 | |||
246 | 812 | *poutbuf = NULL; | |
247 | 812 | *poutbuf_size = 0; | |
248 | |||
249 |
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812 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { |
250 | ✗ | next = buf_size; | |
251 | ✗ | *poutbuf = buf; | |
252 | ✗ | *poutbuf_size = buf_size; | |
253 | /* Assume that data has been packetized into an encapsulation unit. */ | ||
254 | } else { | ||
255 | 812 | next = find_frame_end(pc, buf, buf_size); | |
256 |
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812 | if (!pc->is_synced && next == -1) |
257 | /* No frame start found yet. So throw away the entire buffer. */ | ||
258 | ✗ | return buf_size; | |
259 | |||
260 |
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812 | if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0) |
261 | 750 | return buf_size; | |
262 | } | ||
263 | |||
264 | 62 | *poutbuf = buf; | |
265 | 62 | *poutbuf_size = buf_size; | |
266 | 62 | return next; | |
267 | } | ||
268 | |||
269 | 35 | static av_cold void dirac_parse_close(AVCodecParserContext *s) | |
270 | { | ||
271 | 35 | DiracParseContext *pc = s->priv_data; | |
272 | |||
273 |
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35 | if (pc->buffer_size > 0) |
274 | 2 | av_freep(&pc->buffer); | |
275 | 35 | } | |
276 | |||
277 | const AVCodecParser ff_dirac_parser = { | ||
278 | .codec_ids = { AV_CODEC_ID_DIRAC }, | ||
279 | .priv_data_size = sizeof(DiracParseContext), | ||
280 | .parser_parse = dirac_parse, | ||
281 | .parser_close = dirac_parse_close, | ||
282 | }; | ||
283 |