FFmpeg
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 <limits.h>
25 #include <stdint.h>
26 
27 #include "libavutil/error.h"
28 #include "libavutil/intmath.h"
29 #include "libavutil/macros.h"
30 
31 #include "av1.h"
32 #include "get_bits.h"
33 
34 // OBU header fields + max leb128 length
35 #define MAX_OBU_HEADER_SIZE (2 + 8)
36 
37 typedef struct AV1OBU {
38  /** Size of payload */
39  int size;
40  const uint8_t *data;
41 
42  /**
43  * Size, in bits, of just the data, excluding the trailing_one_bit and
44  * any trailing padding.
45  */
46  int size_bits;
47 
48  /** Size of entire OBU, including header */
49  int raw_size;
50  const uint8_t *raw_data;
51 
52  int type;
53 
56 } AV1OBU;
57 
58 /** An input packet split into OBUs */
59 typedef struct AV1Packet {
61  int nb_obus;
64 } AV1Packet;
65 
66 /**
67  * Extract an OBU from a raw bitstream.
68  *
69  * @note This function does not copy or store any bitstream data. All
70  * the pointers in the AV1OBU structure will be valid as long
71  * as the input buffer also is.
72  */
73 int ff_av1_extract_obu(AV1OBU *obu, const uint8_t *buf, int length,
74  void *logctx);
75 
76 /**
77  * Split an input packet into OBUs.
78  *
79  * @note This function does not copy or store any bitstream data. All
80  * the pointers in the AV1Packet structure will be valid as
81  * long as the input buffer also is.
82  */
83 int ff_av1_packet_split(AV1Packet *pkt, const uint8_t *buf, int length,
84  void *logctx);
85 
86 /**
87  * Free all the allocated memory in the packet.
88  */
90 
91 static inline int64_t leb128(GetBitContext *gb) {
92  int64_t ret = 0;
93  int i;
94 
95  for (i = 0; i < 8; i++) {
96  int byte = get_bits(gb, 8);
97  ret |= (int64_t)(byte & 0x7f) << (i * 7);
98  if (!(byte & 0x80))
99  break;
100  }
101  return ret;
102 }
103 
104 static inline int parse_obu_header(const uint8_t *buf, int buf_size,
105  int64_t *obu_size, int *start_pos, int *type,
106  int *temporal_id, int *spatial_id)
107 {
108  GetBitContext gb;
109  int ret, extension_flag, has_size_flag;
110  int64_t size;
111 
112  ret = init_get_bits8(&gb, buf, FFMIN(buf_size, MAX_OBU_HEADER_SIZE));
113  if (ret < 0)
114  return ret;
115 
116  if (get_bits1(&gb) != 0) // obu_forbidden_bit
117  return AVERROR_INVALIDDATA;
118 
119  *type = get_bits(&gb, 4);
120  extension_flag = get_bits1(&gb);
121  has_size_flag = get_bits1(&gb);
122  skip_bits1(&gb); // obu_reserved_1bit
123 
124  if (extension_flag) {
125  *temporal_id = get_bits(&gb, 3);
126  *spatial_id = get_bits(&gb, 2);
127  skip_bits(&gb, 3); // extension_header_reserved_3bits
128  } else {
129  *temporal_id = *spatial_id = 0;
130  }
131 
132  *obu_size = has_size_flag ? leb128(&gb)
133  : buf_size - 1 - extension_flag;
134 
135  if (get_bits_left(&gb) < 0)
136  return AVERROR_INVALIDDATA;
137 
138  *start_pos = get_bits_count(&gb) / 8;
139 
140  size = *obu_size + *start_pos;
141 
142  if (size > buf_size)
143  return AVERROR_INVALIDDATA;
144 
145  return size;
146 }
147 
148 static inline int get_obu_bit_length(const uint8_t *buf, int size, int type)
149 {
150  int v;
151 
152  /* There are no trailing bits on these */
153  if (type == AV1_OBU_TILE_GROUP ||
154  type == AV1_OBU_TILE_LIST ||
155  type == AV1_OBU_FRAME) {
156  if (size > INT_MAX / 8)
157  return AVERROR(ERANGE);
158  else
159  return size * 8;
160  }
161 
162  while (size > 0 && buf[size - 1] == 0)
163  size--;
164 
165  if (!size)
166  return 0;
167 
168  v = buf[size - 1];
169 
170  if (size > INT_MAX / 8)
171  return AVERROR(ERANGE);
172  size *= 8;
173 
174  /* Remove the trailing_one_bit and following trailing zeros */
175  if (v)
176  size -= ff_ctz(v) + 1;
177 
178  return size;
179 }
180 
181 AVRational ff_av1_framerate(int64_t ticks_per_frame, int64_t units_per_tick,
182  int64_t time_scale);
183 
184 #endif /* AVCODEC_AV1_PARSE_H */
get_bits_left
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:694
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
AV1OBU::size
int size
Size of payload.
Definition: av1_parse.h:39
ff_ctz
#define ff_ctz
Definition: intmath.h:107
leb128
static int64_t leb128(GetBitContext *gb)
Definition: av1_parse.h:91
get_bits_count
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:266
AV1OBU
Definition: av1_parse.h:37
ff_av1_extract_obu
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
AV1OBU::data
const uint8_t * data
Definition: av1_parse.h:40
skip_bits
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:381
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:335
AV1Packet
An input packet split into OBUs.
Definition: av1_parse.h:59
macros.h
GetBitContext
Definition: get_bits.h:108
type
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf type
Definition: writing_filters.txt:86
pkt
AVPacket * pkt
Definition: movenc.c:59
init_get_bits8
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:545
parse_obu_header
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:104
get_bits.h
limits.h
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:388
AV1_OBU_TILE_GROUP
@ AV1_OBU_TILE_GROUP
Definition: av1.h:33
error.h
AV1Packet::nb_obus
int nb_obus
Definition: av1_parse.h:61
AV1_OBU_FRAME
@ AV1_OBU_FRAME
Definition: av1.h:35
ff_av1_framerate
AVRational ff_av1_framerate(int64_t ticks_per_frame, int64_t units_per_tick, int64_t time_scale)
Definition: av1_parse.c:110
get_obu_bit_length
static int get_obu_bit_length(const uint8_t *buf, int size, int type)
Definition: av1_parse.h:148
size
int size
Definition: twinvq_data.h:10344
av1.h
AV1OBU::raw_size
int raw_size
Size of entire OBU, including header.
Definition: av1_parse.h:49
skip_bits1
static void skip_bits1(GetBitContext *s)
Definition: get_bits.h:413
AV1OBU::size_bits
int size_bits
Size, in bits, of just the data, excluding the trailing_one_bit and any trailing padding.
Definition: av1_parse.h:46
AV1Packet::obus_allocated_size
unsigned obus_allocated_size
Definition: av1_parse.h:63
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:245
AV1OBU::spatial_id
int spatial_id
Definition: av1_parse.h:55
AV1OBU::raw_data
const uint8_t * raw_data
Definition: av1_parse.h:50
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
AV1OBU::temporal_id
int temporal_id
Definition: av1_parse.h:54
ret
ret
Definition: filter_design.txt:187
AV1_OBU_TILE_LIST
@ AV1_OBU_TILE_LIST
Definition: av1.h:37
ff_av1_packet_split
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
AV1OBU::type
int type
Definition: av1_parse.h:52
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
AV1Packet::obus
AV1OBU * obus
Definition: av1_parse.h:60
ff_av1_packet_uninit
void ff_av1_packet_uninit(AV1Packet *pkt)
Free all the allocated memory in the packet.
Definition: av1_parse.c:104
MAX_OBU_HEADER_SIZE
#define MAX_OBU_HEADER_SIZE
Definition: av1_parse.h:35
AV1Packet::obus_allocated
int obus_allocated
Definition: av1_parse.h:62
intmath.h