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av1_parse.h (4535B)

      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 #include "leb.h"
     34 
     35 // OBU header fields + max leb128 length
     36 #define MAX_OBU_HEADER_SIZE (2 + 8)
     37 
     38 typedef struct AV1OBU {
     39    /** Size of payload */
     40    int size;
     41    const uint8_t *data;
     42 
     43    /**
     44     * Size, in bits, of just the data, excluding the trailing_one_bit and
     45     * any trailing padding.
     46     */
     47    int size_bits;
     48 
     49    /** Size of entire OBU, including header */
     50    int raw_size;
     51    const uint8_t *raw_data;
     52 
     53    int type;
     54 
     55    int temporal_id;
     56    int spatial_id;
     57 } AV1OBU;
     58 
     59 /** An input packet split into OBUs */
     60 typedef struct AV1Packet {
     61    AV1OBU *obus;
     62    int nb_obus;
     63    int obus_allocated;
     64    unsigned obus_allocated_size;
     65 } AV1Packet;
     66 
     67 /**
     68 * Extract an OBU from a raw bitstream.
     69 *
     70 * @note This function does not copy or store any bitstream data. All
     71 *       the pointers in the AV1OBU structure will be valid as long
     72 *       as the input buffer also is.
     73 */
     74 int ff_av1_extract_obu(AV1OBU *obu, const uint8_t *buf, int length,
     75                       void *logctx);
     76 
     77 /**
     78 * Split an input packet into OBUs.
     79 *
     80 * @note This function does not copy or store any bitstream data. All
     81 *       the pointers in the AV1Packet structure will be valid as
     82 *       long as the input buffer also is.
     83 */
     84 int ff_av1_packet_split(AV1Packet *pkt, const uint8_t *buf, int length,
     85                        void *logctx);
     86 
     87 /**
     88 * Free all the allocated memory in the packet.
     89 */
     90 void ff_av1_packet_uninit(AV1Packet *pkt);
     91 
     92 static inline int parse_obu_header(const uint8_t *buf, int buf_size,
     93                                   int64_t *obu_size, int *start_pos, int *type,
     94                                   int *temporal_id, int *spatial_id)
     95 {
     96    GetBitContext gb;
     97    int ret, extension_flag, has_size_flag;
     98    int64_t size;
     99 
    100    ret = init_get_bits8(&gb, buf, FFMIN(buf_size, MAX_OBU_HEADER_SIZE));
    101    if (ret < 0)
    102        return ret;
    103 
    104    if (get_bits1(&gb) != 0) // obu_forbidden_bit
    105        return AVERROR_INVALIDDATA;
    106 
    107    *type      = get_bits(&gb, 4);
    108    extension_flag = get_bits1(&gb);
    109    has_size_flag  = get_bits1(&gb);
    110    skip_bits1(&gb); // obu_reserved_1bit
    111 
    112    if (extension_flag) {
    113        *temporal_id = get_bits(&gb, 3);
    114        *spatial_id  = get_bits(&gb, 2);
    115        skip_bits(&gb, 3); // extension_header_reserved_3bits
    116    } else {
    117        *temporal_id = *spatial_id = 0;
    118    }
    119 
    120    *obu_size  = has_size_flag ? get_leb128(&gb)
    121                               : buf_size - 1 - extension_flag;
    122 
    123    if (get_bits_left(&gb) < 0)
    124        return AVERROR_INVALIDDATA;
    125 
    126    *start_pos = get_bits_count(&gb) / 8;
    127 
    128    size = *obu_size + *start_pos;
    129 
    130    if (size > buf_size)
    131        return AVERROR_INVALIDDATA;
    132 
    133    return size;
    134 }
    135 
    136 static inline int get_obu_bit_length(const uint8_t *buf, int size, int type)
    137 {
    138    int v;
    139 
    140    /* There are no trailing bits on these */
    141    if (type == AV1_OBU_TILE_GROUP ||
    142        type == AV1_OBU_TILE_LIST ||
    143        type == AV1_OBU_FRAME) {
    144        if (size > INT_MAX / 8)
    145            return AVERROR(ERANGE);
    146        else
    147            return size * 8;
    148    }
    149 
    150    while (size > 0 && buf[size - 1] == 0)
    151        size--;
    152 
    153    if (!size)
    154        return 0;
    155 
    156    v = buf[size - 1];
    157 
    158    if (size > INT_MAX / 8)
    159        return AVERROR(ERANGE);
    160    size *= 8;
    161 
    162    /* Remove the trailing_one_bit and following trailing zeros */
    163    if (v)
    164        size -= ff_ctz(v) + 1;
    165 
    166    return size;
    167 }
    168 
    169 AVRational ff_av1_framerate(int64_t ticks_per_frame, int64_t units_per_tick,
    170                            int64_t time_scale);
    171 
    172 #endif /* AVCODEC_AV1_PARSE_H */