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