2 * AV1 common parsing code
4 * This file is part of FFmpeg.
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.
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.
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
21 #ifndef AVCODEC_AV1_PARSE_H
22 #define AVCODEC_AV1_PARSE_H
27 #include "libavutil/error.h"
28 #include "libavutil/intmath.h"
29 #include "libavutil/macros.h"
34 // OBU header fields + max leb128 length
35 #define MAX_OBU_HEADER_SIZE (2 + 8)
37 typedef struct AV1OBU {
38 /** Size of payload */
43 * Size, in bits, of just the data, excluding the trailing_one_bit and
44 * any trailing padding.
48 /** Size of entire OBU, including header */
50 const uint8_t *raw_data;
52 /** GetBitContext initialized to the start of the payload */
61 /** An input packet split into OBUs */
62 typedef struct AV1Packet {
66 unsigned obus_allocated_size;
70 * Extract an OBU from a raw bitstream.
72 * @note This function does not copy or store any bitstream data. All
73 * the pointers in the AV1OBU structure will be valid as long
74 * as the input buffer also is.
76 int ff_av1_extract_obu(AV1OBU *obu, const uint8_t *buf, int length,
80 * Split an input packet into OBUs.
82 * @note This function does not copy or store any bitstream data. All
83 * the pointers in the AV1Packet structure will be valid as
84 * long as the input buffer also is.
86 int ff_av1_packet_split(AV1Packet *pkt, const uint8_t *buf, int length,
90 * Free all the allocated memory in the packet.
92 void ff_av1_packet_uninit(AV1Packet *pkt);
94 static inline int64_t leb128(GetBitContext *gb) {
98 for (i = 0; i < 8; i++) {
99 int byte = get_bits(gb, 8);
100 ret |= (int64_t)(byte & 0x7f) << (i * 7);
107 static inline int parse_obu_header(const uint8_t *buf, int buf_size,
108 int64_t *obu_size, int *start_pos, int *type,
109 int *temporal_id, int *spatial_id)
112 int ret, extension_flag, has_size_flag;
115 ret = init_get_bits8(&gb, buf, FFMIN(buf_size, MAX_OBU_HEADER_SIZE));
119 if (get_bits1(&gb) != 0) // obu_forbidden_bit
120 return AVERROR_INVALIDDATA;
122 *type = get_bits(&gb, 4);
123 extension_flag = get_bits1(&gb);
124 has_size_flag = get_bits1(&gb);
125 skip_bits1(&gb); // obu_reserved_1bit
127 if (extension_flag) {
128 *temporal_id = get_bits(&gb, 3);
129 *spatial_id = get_bits(&gb, 2);
130 skip_bits(&gb, 3); // extension_header_reserved_3bits
132 *temporal_id = *spatial_id = 0;
135 *obu_size = has_size_flag ? leb128(&gb)
136 : buf_size - 1 - extension_flag;
138 if (get_bits_left(&gb) < 0)
139 return AVERROR_INVALIDDATA;
141 *start_pos = get_bits_count(&gb) / 8;
143 size = *obu_size + *start_pos;
146 return AVERROR_INVALIDDATA;
151 static inline int get_obu_bit_length(const uint8_t *buf, int size, int type)
155 /* There are no trailing bits on these */
156 if (type == AV1_OBU_TILE_GROUP ||
157 type == AV1_OBU_TILE_LIST ||
158 type == AV1_OBU_FRAME) {
159 if (size > INT_MAX / 8)
160 return AVERROR(ERANGE);
165 while (size > 0 && buf[size - 1] == 0)
173 if (size > INT_MAX / 8)
174 return AVERROR(ERANGE);
177 /* Remove the trailing_one_bit and following trailing zeros */
179 size -= ff_ctz(v) + 1;
184 #endif /* AVCODEC_AV1_PARSE_H */