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2ba45a60 DM |
1 | /* |
2 | * VC-1 and WMV3 parser | |
3 | * Copyright (c) 2006-2007 Konstantin Shishkov | |
4 | * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer | |
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 | * VC-1 and WMV3 parser | |
26 | */ | |
27 | ||
28 | #include "libavutil/attributes.h" | |
29 | #include "parser.h" | |
30 | #include "vc1.h" | |
31 | #include "get_bits.h" | |
32 | ||
33 | /** The maximum number of bytes of a sequence, entry point or | |
34 | * frame header whose values we pay any attention to */ | |
35 | #define UNESCAPED_THRESHOLD 37 | |
36 | ||
37 | /** The maximum number of bytes of a sequence, entry point or | |
38 | * frame header which must be valid memory (because they are | |
39 | * used to update the bitstream cache in skip_bits() calls) | |
40 | */ | |
41 | #define UNESCAPED_LIMIT 144 | |
42 | ||
43 | typedef enum { | |
44 | NO_MATCH, | |
45 | ONE_ZERO, | |
46 | TWO_ZEROS, | |
47 | ONE | |
48 | } VC1ParseSearchState; | |
49 | ||
50 | typedef struct { | |
51 | ParseContext pc; | |
52 | VC1Context v; | |
53 | uint8_t prev_start_code; | |
54 | size_t bytes_to_skip; | |
55 | uint8_t unesc_buffer[UNESCAPED_LIMIT]; | |
56 | size_t unesc_index; | |
57 | VC1ParseSearchState search_state; | |
58 | } VC1ParseContext; | |
59 | ||
60 | static void vc1_extract_header(AVCodecParserContext *s, AVCodecContext *avctx, | |
61 | const uint8_t *buf, int buf_size) | |
62 | { | |
63 | /* Parse the header we just finished unescaping */ | |
64 | VC1ParseContext *vpc = s->priv_data; | |
65 | GetBitContext gb; | |
66 | int ret; | |
67 | vpc->v.s.avctx = avctx; | |
68 | vpc->v.parse_only = 1; | |
69 | init_get_bits(&gb, buf, buf_size * 8); | |
70 | switch (vpc->prev_start_code) { | |
71 | case VC1_CODE_SEQHDR & 0xFF: | |
72 | ff_vc1_decode_sequence_header(avctx, &vpc->v, &gb); | |
73 | break; | |
74 | case VC1_CODE_ENTRYPOINT & 0xFF: | |
75 | ff_vc1_decode_entry_point(avctx, &vpc->v, &gb); | |
76 | break; | |
77 | case VC1_CODE_FRAME & 0xFF: | |
78 | if(vpc->v.profile < PROFILE_ADVANCED) | |
79 | ret = ff_vc1_parse_frame_header (&vpc->v, &gb); | |
80 | else | |
81 | ret = ff_vc1_parse_frame_header_adv(&vpc->v, &gb); | |
82 | ||
83 | if (ret < 0) | |
84 | break; | |
85 | ||
86 | /* keep AV_PICTURE_TYPE_BI internal to VC1 */ | |
87 | if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI) | |
88 | s->pict_type = AV_PICTURE_TYPE_B; | |
89 | else | |
90 | s->pict_type = vpc->v.s.pict_type; | |
91 | ||
92 | if (avctx->ticks_per_frame > 1){ | |
93 | // process pulldown flags | |
94 | s->repeat_pict = 1; | |
95 | // Pulldown flags are only valid when 'broadcast' has been set. | |
96 | // So ticks_per_frame will be 2 | |
97 | if (vpc->v.rff){ | |
98 | // repeat field | |
99 | s->repeat_pict = 2; | |
100 | }else if (vpc->v.rptfrm){ | |
101 | // repeat frames | |
102 | s->repeat_pict = vpc->v.rptfrm * 2 + 1; | |
103 | } | |
104 | }else{ | |
105 | s->repeat_pict = 0; | |
106 | } | |
107 | ||
108 | if (vpc->v.broadcast && vpc->v.interlace && !vpc->v.psf) | |
109 | s->field_order = vpc->v.tff ? AV_FIELD_TT : AV_FIELD_BB; | |
110 | else | |
111 | s->field_order = AV_FIELD_PROGRESSIVE; | |
112 | ||
113 | break; | |
114 | } | |
f6fa7814 DM |
115 | if (avctx->framerate.num) |
116 | avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1})); | |
2ba45a60 DM |
117 | } |
118 | ||
119 | static int vc1_parse(AVCodecParserContext *s, | |
120 | AVCodecContext *avctx, | |
121 | const uint8_t **poutbuf, int *poutbuf_size, | |
122 | const uint8_t *buf, int buf_size) | |
123 | { | |
124 | /* Here we do the searching for frame boundaries and headers at | |
125 | * the same time. Only a minimal amount at the start of each | |
126 | * header is unescaped. */ | |
127 | VC1ParseContext *vpc = s->priv_data; | |
128 | int pic_found = vpc->pc.frame_start_found; | |
129 | uint8_t *unesc_buffer = vpc->unesc_buffer; | |
130 | size_t unesc_index = vpc->unesc_index; | |
131 | VC1ParseSearchState search_state = vpc->search_state; | |
132 | int start_code_found = 0; | |
133 | int next = END_NOT_FOUND; | |
134 | int i = vpc->bytes_to_skip; | |
135 | ||
136 | if (pic_found && buf_size == 0) { | |
137 | /* EOF considered as end of frame */ | |
138 | memset(unesc_buffer + unesc_index, 0, UNESCAPED_THRESHOLD - unesc_index); | |
139 | vc1_extract_header(s, avctx, unesc_buffer, unesc_index); | |
140 | next = 0; | |
141 | } | |
142 | while (i < buf_size) { | |
143 | uint8_t b; | |
144 | start_code_found = 0; | |
145 | while (i < buf_size && unesc_index < UNESCAPED_THRESHOLD) { | |
146 | b = buf[i++]; | |
147 | unesc_buffer[unesc_index++] = b; | |
148 | if (search_state <= ONE_ZERO) | |
149 | search_state = b ? NO_MATCH : search_state + 1; | |
150 | else if (search_state == TWO_ZEROS) { | |
151 | if (b == 1) | |
152 | search_state = ONE; | |
153 | else if (b > 1) { | |
154 | if (b == 3) | |
155 | unesc_index--; // swallow emulation prevention byte | |
156 | search_state = NO_MATCH; | |
157 | } | |
158 | } | |
159 | else { // search_state == ONE | |
160 | // Header unescaping terminates early due to detection of next start code | |
161 | search_state = NO_MATCH; | |
162 | start_code_found = 1; | |
163 | break; | |
164 | } | |
165 | } | |
166 | if ((s->flags & PARSER_FLAG_COMPLETE_FRAMES) && | |
167 | unesc_index >= UNESCAPED_THRESHOLD && | |
168 | vpc->prev_start_code == (VC1_CODE_FRAME & 0xFF)) | |
169 | { | |
170 | // No need to keep scanning the rest of the buffer for | |
171 | // start codes if we know it contains a complete frame and | |
172 | // we've already unescaped all we need of the frame header | |
173 | vc1_extract_header(s, avctx, unesc_buffer, unesc_index); | |
174 | break; | |
175 | } | |
176 | if (unesc_index >= UNESCAPED_THRESHOLD && !start_code_found) { | |
177 | while (i < buf_size) { | |
178 | if (search_state == NO_MATCH) { | |
179 | i += vpc->v.vc1dsp.startcode_find_candidate(buf + i, buf_size - i); | |
180 | if (i < buf_size) { | |
181 | search_state = ONE_ZERO; | |
182 | } | |
183 | i++; | |
184 | } else { | |
185 | b = buf[i++]; | |
186 | if (search_state == ONE_ZERO) | |
187 | search_state = b ? NO_MATCH : TWO_ZEROS; | |
188 | else if (search_state == TWO_ZEROS) { | |
189 | if (b >= 1) | |
190 | search_state = b == 1 ? ONE : NO_MATCH; | |
191 | } | |
192 | else { // search_state == ONE | |
193 | search_state = NO_MATCH; | |
194 | start_code_found = 1; | |
195 | break; | |
196 | } | |
197 | } | |
198 | } | |
199 | } | |
200 | if (start_code_found) { | |
201 | vc1_extract_header(s, avctx, unesc_buffer, unesc_index); | |
202 | ||
203 | vpc->prev_start_code = b; | |
204 | unesc_index = 0; | |
205 | ||
206 | if (!(s->flags & PARSER_FLAG_COMPLETE_FRAMES)) { | |
207 | if (!pic_found && (b == (VC1_CODE_FRAME & 0xFF) || b == (VC1_CODE_FIELD & 0xFF))) { | |
208 | pic_found = 1; | |
209 | } | |
210 | else if (pic_found && b != (VC1_CODE_FIELD & 0xFF) && b != (VC1_CODE_SLICE & 0xFF)) { | |
211 | next = i - 4; | |
212 | pic_found = b == (VC1_CODE_FRAME & 0xFF); | |
213 | break; | |
214 | } | |
215 | } | |
216 | } | |
217 | } | |
218 | ||
219 | vpc->pc.frame_start_found = pic_found; | |
220 | vpc->unesc_index = unesc_index; | |
221 | vpc->search_state = search_state; | |
222 | ||
223 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { | |
224 | next = buf_size; | |
225 | } else { | |
226 | if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) { | |
227 | vpc->bytes_to_skip = 0; | |
228 | *poutbuf = NULL; | |
229 | *poutbuf_size = 0; | |
230 | return buf_size; | |
231 | } | |
232 | } | |
233 | ||
234 | /* If we return with a valid pointer to a combined frame buffer | |
235 | * then on the next call then we'll have been unhelpfully rewound | |
236 | * by up to 4 bytes (depending upon whether the start code | |
237 | * overlapped the input buffer, and if so by how much). We don't | |
238 | * want this: it will either cause spurious second detections of | |
239 | * the start code we've already seen, or cause extra bytes to be | |
240 | * inserted at the start of the unescaped buffer. */ | |
241 | vpc->bytes_to_skip = 4; | |
242 | if (next < 0 && next != END_NOT_FOUND) | |
243 | vpc->bytes_to_skip += next; | |
244 | ||
245 | *poutbuf = buf; | |
246 | *poutbuf_size = buf_size; | |
247 | return next; | |
248 | } | |
249 | ||
250 | static int vc1_split(AVCodecContext *avctx, | |
251 | const uint8_t *buf, int buf_size) | |
252 | { | |
253 | int i; | |
254 | uint32_t state= -1; | |
255 | int charged=0; | |
256 | ||
257 | for(i=0; i<buf_size; i++){ | |
258 | state= (state<<8) | buf[i]; | |
259 | if(IS_MARKER(state)){ | |
260 | if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){ | |
261 | charged=1; | |
262 | }else if(charged){ | |
263 | return i-3; | |
264 | } | |
265 | } | |
266 | } | |
267 | return 0; | |
268 | } | |
269 | ||
270 | static av_cold int vc1_parse_init(AVCodecParserContext *s) | |
271 | { | |
272 | VC1ParseContext *vpc = s->priv_data; | |
273 | vpc->v.s.slice_context_count = 1; | |
274 | vpc->v.first_pic_header_flag = 1; | |
275 | vpc->prev_start_code = 0; | |
276 | vpc->bytes_to_skip = 0; | |
277 | vpc->unesc_index = 0; | |
278 | vpc->search_state = NO_MATCH; | |
279 | return ff_vc1_init_common(&vpc->v); | |
280 | } | |
281 | ||
282 | AVCodecParser ff_vc1_parser = { | |
283 | .codec_ids = { AV_CODEC_ID_VC1 }, | |
284 | .priv_data_size = sizeof(VC1ParseContext), | |
285 | .parser_init = vc1_parse_init, | |
286 | .parser_parse = vc1_parse, | |
287 | .parser_close = ff_parse_close, | |
288 | .split = vc1_split, | |
289 | }; |