1 /*
2 * AV1 common parsing code
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #ifndef AVCODEC_AV1_PARSE_H
22 #define AVCODEC_AV1_PARSE_H
23
24 #include <stdint.h>
25
26 #include "av1.h"
27 #include "avcodec.h"
28 #include "get_bits.h"
29
30 typedef struct AV1OBU {
31 /** Size of payload */
32 int size;
33 const uint8_t *data;
34
35 /**
36 * Size, in bits, of just the data, excluding the trailing_one_bit and
37 * any trailing padding.
38 */
39 int size_bits;
40
41 /** Size of entire OBU, including header */
42 int raw_size;
43 const uint8_t *raw_data;
44
45 /** GetBitContext initialized to the start of the payload */
46 GetBitContext gb;
47
48 int type;
49
50 int temporal_id;
51 int spatial_id;
52 } AV1OBU;
53
54 /** An input packet split into OBUs */
55 typedef struct AV1Packet {
56 AV1OBU *obus;
57 int nb_obus;
58 int obus_allocated;
59 unsigned obus_allocated_size;
60 } AV1Packet;
61
62 /**
63 * Extract an OBU from a raw bitstream.
64 *
65 * @note This function does not copy or store any bitstream data. All
66 * the pointers in the AV1OBU structure will be valid as long
67 * as the input buffer also is.
68 */
69 int ff_av1_extract_obu(AV1OBU *obu, const uint8_t *buf, int length,
70 void *logctx);
71
72 /**
73 * Split an input packet into OBUs.
74 *
75 * @note This function does not copy or store any bitstream data. All
76 * the pointers in the AV1Packet structure will be valid as
77 * long as the input buffer also is.
78 */
79 int ff_av1_packet_split(AV1Packet *pkt, const uint8_t *buf, int length,
80 void *logctx);
81
82 /**
83 * Free all the allocated memory in the packet.
84 */
85 void ff_av1_packet_uninit(AV1Packet *pkt);
86
leb128(GetBitContext * gb)87 static inline int64_t leb128(GetBitContext *gb) {
88 int64_t ret = 0;
89 int i;
90
91 for (i = 0; i < 8; i++) {
92 int byte = get_bits(gb, 8);
93 ret |= (int64_t)(byte & 0x7f) << (i * 7);
94 if (!(byte & 0x80))
95 break;
96 }
97 return ret;
98 }
99
parse_obu_header(const uint8_t * buf,int buf_size,int64_t * obu_size,int * start_pos,int * type,int * temporal_id,int * spatial_id)100 static inline int parse_obu_header(const uint8_t *buf, int buf_size,
101 int64_t *obu_size, int *start_pos, int *type,
102 int *temporal_id, int *spatial_id)
103 {
104 GetBitContext gb;
105 int ret, extension_flag, has_size_flag;
106 int64_t size;
107
108 ret = init_get_bits8(&gb, buf, FFMIN(buf_size, 2 + 8)); // OBU header fields + max leb128 length
109 if (ret < 0)
110 return ret;
111
112 if (get_bits1(&gb) != 0) // obu_forbidden_bit
113 return AVERROR_INVALIDDATA;
114
115 *type = get_bits(&gb, 4);
116 extension_flag = get_bits1(&gb);
117 has_size_flag = get_bits1(&gb);
118 skip_bits1(&gb); // obu_reserved_1bit
119
120 if (extension_flag) {
121 *temporal_id = get_bits(&gb, 3);
122 *spatial_id = get_bits(&gb, 2);
123 skip_bits(&gb, 3); // extension_header_reserved_3bits
124 } else {
125 *temporal_id = *spatial_id = 0;
126 }
127
128 *obu_size = has_size_flag ? leb128(&gb)
129 : buf_size - 1 - extension_flag;
130
131 if (get_bits_left(&gb) < 0)
132 return AVERROR_INVALIDDATA;
133
134 *start_pos = get_bits_count(&gb) / 8;
135
136 size = *obu_size + *start_pos;
137
138 if (size > buf_size)
139 return AVERROR_INVALIDDATA;
140
141 return size;
142 }
143
get_obu_bit_length(const uint8_t * buf,int size,int type)144 static inline int get_obu_bit_length(const uint8_t *buf, int size, int type)
145 {
146 int v;
147
148 /* There are no trailing bits on these */
149 if (type == AV1_OBU_TILE_GROUP ||
150 type == AV1_OBU_TILE_LIST ||
151 type == AV1_OBU_FRAME) {
152 if (size > INT_MAX / 8)
153 return AVERROR(ERANGE);
154 else
155 return size * 8;
156 }
157
158 while (size > 0 && buf[size - 1] == 0)
159 size--;
160
161 if (!size)
162 return 0;
163
164 v = buf[size - 1];
165
166 if (size > INT_MAX / 8)
167 return AVERROR(ERANGE);
168 size *= 8;
169
170 /* Remove the trailing_one_bit and following trailing zeros */
171 if (v)
172 size -= ff_ctz(v) + 1;
173
174 return size;
175 }
176
177 #endif /* AVCODEC_AV1_PARSE_H */
178