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2ba45a60 DM |
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/intreadwrite.h" | |
33 | #include "libavutil/mem.h" | |
34 | ||
35 | #include "parser.h" | |
36 | ||
37 | #define DIRAC_PARSE_INFO_PREFIX 0x42424344 | |
38 | ||
39 | /** | |
40 | * Find the end of the current frame in the bitstream. | |
41 | * @return the position of the first byte of the next frame or -1 | |
42 | */ | |
43 | typedef struct DiracParseContext { | |
44 | int state; | |
45 | int is_synced; | |
46 | int sync_offset; | |
47 | int header_bytes_needed; | |
48 | int overread_index; | |
49 | int buffer_size; | |
50 | int index; | |
51 | uint8_t *buffer; | |
52 | int dirac_unit_size; | |
53 | uint8_t *dirac_unit; | |
54 | } DiracParseContext; | |
55 | ||
56 | static int find_frame_end(DiracParseContext *pc, | |
57 | const uint8_t *buf, int buf_size) | |
58 | { | |
59 | uint32_t state = pc->state; | |
60 | int i = 0; | |
61 | ||
62 | if (!pc->is_synced) { | |
63 | for (i = 0; i < buf_size; i++) { | |
64 | state = (state << 8) | buf[i]; | |
65 | if (state == DIRAC_PARSE_INFO_PREFIX) { | |
66 | state = -1; | |
67 | pc->is_synced = 1; | |
68 | pc->header_bytes_needed = 9; | |
69 | pc->sync_offset = i; | |
70 | break; | |
71 | } | |
72 | } | |
73 | } | |
74 | ||
75 | if (pc->is_synced) { | |
76 | pc->sync_offset = 0; | |
77 | for (; i < buf_size; i++) { | |
78 | if (state == DIRAC_PARSE_INFO_PREFIX) { | |
79 | if ((buf_size - i) >= pc->header_bytes_needed) { | |
80 | pc->state = -1; | |
81 | return i + pc->header_bytes_needed; | |
82 | } else { | |
83 | pc->header_bytes_needed = 9 - (buf_size - i); | |
84 | break; | |
85 | } | |
86 | } else | |
87 | state = (state << 8) | buf[i]; | |
88 | } | |
89 | } | |
90 | pc->state = state; | |
91 | return -1; | |
92 | } | |
93 | ||
94 | typedef struct DiracParseUnit { | |
95 | int next_pu_offset; | |
96 | int prev_pu_offset; | |
97 | uint8_t pu_type; | |
98 | } DiracParseUnit; | |
99 | ||
100 | static int unpack_parse_unit(DiracParseUnit *pu, DiracParseContext *pc, | |
101 | int offset) | |
102 | { | |
103 | uint8_t *start = pc->buffer + offset; | |
104 | uint8_t *end = pc->buffer + pc->index; | |
105 | if (start < pc->buffer || (start + 13 > end)) | |
106 | return 0; | |
107 | pu->pu_type = start[4]; | |
108 | ||
109 | pu->next_pu_offset = AV_RB32(start + 5); | |
110 | pu->prev_pu_offset = AV_RB32(start + 9); | |
111 | ||
112 | if (pu->pu_type == 0x10 && pu->next_pu_offset == 0) | |
113 | pu->next_pu_offset = 13; | |
114 | ||
115 | return 1; | |
116 | } | |
117 | ||
118 | static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx, | |
119 | int next, const uint8_t **buf, int *buf_size) | |
120 | { | |
121 | int parse_timing_info = (s->pts == AV_NOPTS_VALUE && | |
122 | s->dts == AV_NOPTS_VALUE); | |
123 | DiracParseContext *pc = s->priv_data; | |
124 | ||
125 | if (pc->overread_index) { | |
126 | memcpy(pc->buffer, pc->buffer + pc->overread_index, | |
127 | pc->index - pc->overread_index); | |
128 | pc->index -= pc->overread_index; | |
129 | pc->overread_index = 0; | |
130 | if (*buf_size == 0 && pc->buffer[4] == 0x10) { | |
131 | *buf = pc->buffer; | |
132 | *buf_size = pc->index; | |
133 | return 0; | |
134 | } | |
135 | } | |
136 | ||
137 | if (next == -1) { | |
138 | /* Found a possible frame start but not a frame end */ | |
139 | void *new_buffer = | |
140 | av_fast_realloc(pc->buffer, &pc->buffer_size, | |
141 | pc->index + (*buf_size - pc->sync_offset)); | |
f6fa7814 DM |
142 | if (!new_buffer) |
143 | return AVERROR(ENOMEM); | |
2ba45a60 DM |
144 | pc->buffer = new_buffer; |
145 | memcpy(pc->buffer + pc->index, (*buf + pc->sync_offset), | |
146 | *buf_size - pc->sync_offset); | |
147 | pc->index += *buf_size - pc->sync_offset; | |
148 | return -1; | |
149 | } else { | |
150 | /* Found a possible frame start and a possible frame end */ | |
151 | DiracParseUnit pu1, pu; | |
152 | void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, | |
153 | pc->index + next); | |
f6fa7814 DM |
154 | if (!new_buffer) |
155 | return AVERROR(ENOMEM); | |
2ba45a60 DM |
156 | pc->buffer = new_buffer; |
157 | memcpy(pc->buffer + pc->index, *buf, next); | |
158 | pc->index += next; | |
159 | ||
160 | /* Need to check if we have a valid Parse Unit. We can't go by the | |
161 | * sync pattern 'BBCD' alone because arithmetic coding of the residual | |
162 | * and motion data can cause the pattern triggering a false start of | |
163 | * frame. So check if the previous parse offset of the next parse unit | |
164 | * is equal to the next parse offset of the current parse unit then | |
165 | * we can be pretty sure that we have a valid parse unit */ | |
166 | if (!unpack_parse_unit(&pu1, pc, pc->index - 13) || | |
167 | !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) || | |
168 | pu.next_pu_offset != pu1.prev_pu_offset || | |
169 | pc->index < pc->dirac_unit_size + 13LL + pu1.prev_pu_offset | |
170 | ) { | |
171 | pc->index -= 9; | |
172 | *buf_size = next - 9; | |
173 | pc->header_bytes_needed = 9; | |
174 | return -1; | |
175 | } | |
176 | ||
177 | /* All non-frame data must be accompanied by frame data. This is to | |
178 | * ensure that pts is set correctly. So if the current parse unit is | |
179 | * not frame data, wait for frame data to come along */ | |
180 | ||
181 | pc->dirac_unit = pc->buffer + pc->index - 13 - | |
182 | pu1.prev_pu_offset - pc->dirac_unit_size; | |
183 | ||
184 | pc->dirac_unit_size += pu.next_pu_offset; | |
185 | ||
186 | if ((pu.pu_type & 0x08) != 0x08) { | |
187 | pc->header_bytes_needed = 9; | |
188 | *buf_size = next; | |
189 | return -1; | |
190 | } | |
191 | ||
192 | /* Get the picture number to set the pts and dts*/ | |
193 | if (parse_timing_info) { | |
194 | uint8_t *cur_pu = pc->buffer + | |
195 | pc->index - 13 - pu1.prev_pu_offset; | |
196 | int pts = AV_RB32(cur_pu + 13); | |
197 | if (s->last_pts == 0 && s->last_dts == 0) | |
198 | s->dts = pts - 1; | |
199 | else | |
200 | s->dts = s->last_dts + 1; | |
201 | s->pts = pts; | |
202 | if (!avctx->has_b_frames && (cur_pu[4] & 0x03)) | |
203 | avctx->has_b_frames = 1; | |
204 | } | |
205 | if (avctx->has_b_frames && s->pts == s->dts) | |
206 | s->pict_type = AV_PICTURE_TYPE_B; | |
207 | ||
208 | /* Finally have a complete Dirac data unit */ | |
209 | *buf = pc->dirac_unit; | |
210 | *buf_size = pc->dirac_unit_size; | |
211 | ||
212 | pc->dirac_unit_size = 0; | |
213 | pc->overread_index = pc->index - 13; | |
214 | pc->header_bytes_needed = 9; | |
215 | } | |
216 | return next; | |
217 | } | |
218 | ||
219 | static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx, | |
220 | const uint8_t **poutbuf, int *poutbuf_size, | |
221 | const uint8_t *buf, int buf_size) | |
222 | { | |
223 | DiracParseContext *pc = s->priv_data; | |
224 | int next; | |
225 | ||
226 | *poutbuf = NULL; | |
227 | *poutbuf_size = 0; | |
228 | ||
229 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { | |
230 | next = buf_size; | |
231 | *poutbuf = buf; | |
232 | *poutbuf_size = buf_size; | |
233 | /* Assume that data has been packetized into an encapsulation unit. */ | |
234 | } else { | |
235 | next = find_frame_end(pc, buf, buf_size); | |
236 | if (!pc->is_synced && next == -1) | |
237 | /* No frame start found yet. So throw away the entire buffer. */ | |
238 | return buf_size; | |
239 | ||
240 | if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0) | |
241 | return buf_size; | |
242 | } | |
243 | ||
244 | *poutbuf = buf; | |
245 | *poutbuf_size = buf_size; | |
246 | return next; | |
247 | } | |
248 | ||
249 | static void dirac_parse_close(AVCodecParserContext *s) | |
250 | { | |
251 | DiracParseContext *pc = s->priv_data; | |
252 | ||
253 | if (pc->buffer_size > 0) | |
f6fa7814 | 254 | av_freep(&pc->buffer); |
2ba45a60 DM |
255 | } |
256 | ||
257 | AVCodecParser ff_dirac_parser = { | |
258 | .codec_ids = { AV_CODEC_ID_DIRAC }, | |
259 | .priv_data_size = sizeof(DiracParseContext), | |
260 | .parser_parse = dirac_parse, | |
261 | .parser_close = dirac_parse_close, | |
262 | }; |