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 // OBU header fields + max leb128 length
31 #define MAX_OBU_HEADER_SIZE (2 + 8)
32
33 typedef struct AV1OBU {
34 /** Size of payload */
35 int size;
36 const uint8_t *data;
37
38 /**
39 * Size, in bits, of just the data, excluding the trailing_one_bit and
40 * any trailing padding.
41 */
42 int size_bits;
43
44 /** Size of entire OBU, including header */
45 int raw_size;
46 const uint8_t *raw_data;
47
48 /** GetBitContext initialized to the start of the payload */
49 GetBitContext gb;
50
51 int type;
52
53 int temporal_id;
54 int spatial_id;
55 } AV1OBU;
56
57 /** An input packet split into OBUs */
58 typedef struct AV1Packet {
59 AV1OBU *obus;
60 int nb_obus;
61 int obus_allocated;
62 unsigned obus_allocated_size;
63 } AV1Packet;
64
65 /**
66 * Extract an OBU from a raw bitstream.
67 *
68 * @note This function does not copy or store any bitstream data. All
69 * the pointers in the AV1OBU structure will be valid as long
70 * as the input buffer also is.
71 */
72 int ff_av1_extract_obu(AV1OBU *obu, const uint8_t *buf, int length,
73 void *logctx);
74
75 /**
76 * Split an input packet into OBUs.
77 *
78 * @note This function does not copy or store any bitstream data. All
79 * the pointers in the AV1Packet structure will be valid as
80 * long as the input buffer also is.
81 */
82 int ff_av1_packet_split(AV1Packet *pkt, const uint8_t *buf, int length,
83 void *logctx);
84
85 /**
86 * Free all the allocated memory in the packet.
87 */
88 void ff_av1_packet_uninit(AV1Packet *pkt);
89
leb128(GetBitContext * gb)90 static inline int64_t leb128(GetBitContext *gb) {
91 int64_t ret = 0;
92 int i;
93
94 for (i = 0; i < 8; i++) {
95 int byte = get_bits(gb, 8);
96 ret |= (int64_t)(byte & 0x7f) << (i * 7);
97 if (!(byte & 0x80))
98 break;
99 }
100 return ret;
101 }
102
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)103 static inline int parse_obu_header(const uint8_t *buf, int buf_size,
104 int64_t *obu_size, int *start_pos, int *type,
105 int *temporal_id, int *spatial_id)
106 {
107 GetBitContext gb;
108 int ret, extension_flag, has_size_flag;
109 int64_t size;
110
111 ret = init_get_bits8(&gb, buf, FFMIN(buf_size, MAX_OBU_HEADER_SIZE));
112 if (ret < 0)
113 return ret;
114
115 if (get_bits1(&gb) != 0) // obu_forbidden_bit
116 return AVERROR_INVALIDDATA;
117
118 *type = get_bits(&gb, 4);
119 extension_flag = get_bits1(&gb);
120 has_size_flag = get_bits1(&gb);
121 skip_bits1(&gb); // obu_reserved_1bit
122
123 if (extension_flag) {
124 *temporal_id = get_bits(&gb, 3);
125 *spatial_id = get_bits(&gb, 2);
126 skip_bits(&gb, 3); // extension_header_reserved_3bits
127 } else {
128 *temporal_id = *spatial_id = 0;
129 }
130
131 *obu_size = has_size_flag ? leb128(&gb)
132 : buf_size - 1 - extension_flag;
133
134 if (get_bits_left(&gb) < 0)
135 return AVERROR_INVALIDDATA;
136
137 *start_pos = get_bits_count(&gb) / 8;
138
139 size = *obu_size + *start_pos;
140
141 if (size > buf_size)
142 return AVERROR_INVALIDDATA;
143
144 return size;
145 }
146
get_obu_bit_length(const uint8_t * buf,int size,int type)147 static inline int get_obu_bit_length(const uint8_t *buf, int size, int type)
148 {
149 int v;
150
151 /* There are no trailing bits on these */
152 if (type == AV1_OBU_TILE_GROUP ||
153 type == AV1_OBU_TILE_LIST ||
154 type == AV1_OBU_FRAME) {
155 if (size > INT_MAX / 8)
156 return AVERROR(ERANGE);
157 else
158 return size * 8;
159 }
160
161 while (size > 0 && buf[size - 1] == 0)
162 size--;
163
164 if (!size)
165 return 0;
166
167 v = buf[size - 1];
168
169 if (size > INT_MAX / 8)
170 return AVERROR(ERANGE);
171 size *= 8;
172
173 /* Remove the trailing_one_bit and following trailing zeros */
174 if (v)
175 size -= ff_ctz(v) + 1;
176
177 return size;
178 }
179
180 #endif /* AVCODEC_AV1_PARSE_H */
181