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
|
/* nal_units.c
*
* Copyright (c) 2003-2019 HandBrake Team
* This file is part of the HandBrake source code.
* Homepage: <http://handbrake.fr/>.
* It may be used under the terms of the GNU General Public License v2.
* For full terms see the file COPYING file or visit http://www.gnu.org/licenses/gpl-2.0.html
*/
#include <stdint.h>
#include <string.h>
#include "common.h"
#include "nal_units.h"
static const uint8_t hb_annexb_startcode[] = { 0x00, 0x00, 0x00, 0x01, };
size_t hb_nal_unit_write_annexb(uint8_t *buf,
const uint8_t *nal_unit,
const size_t nal_unit_size)
{
if (buf != NULL)
{
memcpy(buf, hb_annexb_startcode, sizeof(hb_annexb_startcode));
memcpy(buf + sizeof(hb_annexb_startcode), nal_unit, nal_unit_size);
}
return sizeof(hb_annexb_startcode) + nal_unit_size;
}
size_t hb_nal_unit_write_isomp4(uint8_t *buf,
const uint8_t *nal_unit,
const size_t nal_unit_size)
{
int i;
uint8_t length[4]; // 4-byte length replaces Annex B start code prefix
if (buf != NULL)
{
for (i = 0; i < sizeof(length); i++)
{
length[i] = (nal_unit_size >> (8 * (sizeof(length) - 1 - i))) & 0xff;
}
memcpy(buf, &length[0], sizeof(length));
memcpy(buf + sizeof(length), nal_unit, nal_unit_size);
}
return sizeof(length) + nal_unit_size;
}
uint8_t* hb_annexb_find_next_nalu(const uint8_t *start, size_t *size)
{
uint8_t *nal = NULL;
uint8_t *buf = (uint8_t*)start;
uint8_t *end = (uint8_t*)start + *size;
/* Look for an Annex B start code prefix (3-byte sequence == 1) */
while (end - buf > 3)
{
if (!buf[0] && !buf[1] && buf[2] == 1)
{
nal = (buf += 3); // NAL unit begins after start code
break;
}
buf++;
}
if (nal == NULL)
{
*size = 0;
return NULL;
}
/*
* Start code prefix found, look for the next one to determine the size
*
* A 4-byte sequence == 1 is also a start code, so check for a 3-byte
* sequence == 0 too (start code emulation prevention will prevent such a
* sequence from occurring outside of a start code prefix)
*/
while (end - buf > 3)
{
if (!buf[0] && !buf[1] && (!buf[2] || buf[2] == 1))
{
end = buf;
break;
}
buf++;
}
*size = end - nal;
return nal;
}
hb_buffer_t* hb_nal_bitstream_annexb_to_mp4(const uint8_t *data,
const size_t size)
{
hb_buffer_t *out;
uint8_t *buf, *end;
size_t out_size, buf_size;
out_size = 0;
buf_size = size;
buf = (uint8_t*)data;
end = (uint8_t*)data + size;
while ((buf = hb_annexb_find_next_nalu(buf, &buf_size)) != NULL)
{
out_size += hb_nal_unit_write_isomp4(NULL, buf, buf_size);
buf_size = end - buf;
}
out = hb_buffer_init(out_size);
if (out == NULL)
{
hb_error("hb_nal_bitstream_annexb_to_mp4: hb_buffer_init failed");
return NULL;
}
out_size = 0;
buf_size = size;
buf = (uint8_t*)data;
end = (uint8_t*)data + size;
while ((buf = hb_annexb_find_next_nalu(buf, &buf_size)) != NULL)
{
out_size += hb_nal_unit_write_isomp4(out->data + out_size, buf, buf_size);
buf_size = end - buf;
}
return out;
}
static size_t mp4_nal_unit_length(const uint8_t *data,
const size_t nal_length_size,
size_t *nal_unit_length)
{
uint8_t i;
/* In MP4, NAL units are preceded by a 2-4 byte length field */
for (i = 0, *nal_unit_length = 0; i < nal_length_size; i++)
{
*nal_unit_length |= data[i] << (8 * (nal_length_size - 1 - i));
}
return nal_length_size;
}
hb_buffer_t* hb_nal_bitstream_mp4_to_annexb(const uint8_t *data,
const size_t size,
const uint8_t nal_length_size)
{
hb_buffer_t *out;
uint8_t *buf, *end;
size_t out_size, nal_size;
out_size = 0;
buf = (uint8_t*)data;
end = (uint8_t*)data + size;
while (end - buf > nal_length_size)
{
buf += mp4_nal_unit_length(buf, nal_length_size, &nal_size);
if (end - buf < nal_size)
{
hb_log("hb_nal_bitstream_mp4_to_annexb: truncated bitstream"
" (remaining: %lu, expected: %lu)", end - buf, nal_size);
return NULL;
}
out_size += hb_nal_unit_write_annexb(NULL, buf, nal_size);
buf += nal_size;
}
out = hb_buffer_init(out_size);
if (out == NULL)
{
hb_error("hb_nal_bitstream_mp4_to_annexb: hb_buffer_init failed");
return NULL;
}
out_size = 0;
buf = (uint8_t*)data;
end = (uint8_t*)data + size;
while (end - buf > nal_length_size)
{
buf += mp4_nal_unit_length(buf, nal_length_size, &nal_size);
out_size += hb_nal_unit_write_annexb(out->data + out_size, buf, nal_size);
buf += nal_size;
}
return out;
}
|
