FFmpeg  4.3
av1_parse.h
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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 */
47 
48  int type;
49 
52 } AV1OBU;
53 
54 /** An input packet split into OBUs */
55 typedef struct AV1Packet {
57  int nb_obus;
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  */
86 
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 
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 {
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 
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 */
int ff_av1_extract_obu(AV1OBU *obu, const uint8_t *buf, int length, void *logctx)
Extract an OBU from a raw bitstream.
Definition: av1_parse.c:29
#define ff_ctz
Definition: intmath.h:106
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
const uint8_t * raw_data
Definition: av1_parse.h:43
int spatial_id
Definition: av1_parse.h:51
static AVPacket pkt
const uint8_t * data
Definition: av1_parse.h:33
uint8_t
int ff_av1_packet_split(AV1Packet *pkt, const uint8_t *buf, int length, void *logctx)
Split an input packet into OBUs.
Definition: av1_parse.c:56
int size
Size of payload.
Definition: av1_parse.h:32
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:219
bitstream reader API header.
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:849
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
#define AVERROR(e)
Definition: error.h:43
GetBitContext gb
GetBitContext initialized to the start of the payload.
Definition: av1_parse.h:46
#define FFMIN(a, b)
Definition: common.h:96
int temporal_id
Definition: av1_parse.h:50
static int 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)
Definition: av1_parse.h:100
int nb_obus
Definition: av1_parse.h:57
AV1OBU * obus
Definition: av1_parse.h:56
Libavcodec external API header.
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:677
AV1 common definitions.
unsigned obus_allocated_size
Definition: av1_parse.h:59
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:498
static void skip_bits1(GetBitContext *s)
Definition: get_bits.h:538
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:467
int type
Definition: av1_parse.h:48
int obus_allocated
Definition: av1_parse.h:58
int size_bits
Size, in bits, of just the data, excluding the trailing_one_bit and any trailing padding.
Definition: av1_parse.h:39
An input packet split into OBUs.
Definition: av1_parse.h:55
int raw_size
Size of entire OBU, including header.
Definition: av1_parse.h:42
static int64_t leb128(GetBitContext *gb)
Definition: av1_parse.h:87
static int get_obu_bit_length(const uint8_t *buf, int size, int type)
Definition: av1_parse.h:144
void ff_av1_packet_uninit(AV1Packet *pkt)
Free all the allocated memory in the packet.
Definition: av1_parse.c:106