| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * Shared definitions and helper functions for | ||
| 3 | * AV1 (de)packetization. | ||
| 4 | * Copyright (c) 2024 Axis Communications | ||
| 5 | * | ||
| 6 | * This file is part of FFmpeg. | ||
| 7 | * | ||
| 8 | * FFmpeg is free software; you can redistribute it and/or | ||
| 9 | * modify it under the terms of the GNU Lesser General Public | ||
| 10 | * License as published by the Free Software Foundation; either | ||
| 11 | * version 2.1 of the License, or (at your option) any later version. | ||
| 12 | * | ||
| 13 | * FFmpeg is distributed in the hope that it will be useful, | ||
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| 16 | * Lesser General Public License for more details. | ||
| 17 | * | ||
| 18 | * You should have received a copy of the GNU Lesser General Public | ||
| 19 | * License along with FFmpeg; if not, write to the Free Software | ||
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
| 21 | */ | ||
| 22 | |||
| 23 | /** | ||
| 24 | * @file | ||
| 25 | * @brief shared defines and functions for AV1 RTP dec/enc | ||
| 26 | * @author Chris Hodges <chris.hodges@axis.com> | ||
| 27 | */ | ||
| 28 | |||
| 29 | #ifndef AVFORMAT_RTP_AV1_H | ||
| 30 | #define AVFORMAT_RTP_AV1_H | ||
| 31 | |||
| 32 | #include <stdint.h> | ||
| 33 | |||
| 34 | #include "libavutil/log.h" | ||
| 35 | |||
| 36 | // define a couple of flags and bit fields | ||
| 37 | #define AV1B_OBU_FORBIDDEN 7 | ||
| 38 | #define AV1F_OBU_FORBIDDEN (1u << AV1B_OBU_FORBIDDEN) | ||
| 39 | #define AV1S_OBU_TYPE 3 | ||
| 40 | #define AV1M_OBU_TYPE 15 | ||
| 41 | #define AV1B_OBU_EXTENSION_FLAG 2 | ||
| 42 | #define AV1F_OBU_EXTENSION_FLAG (1u << AV1B_OBU_EXTENSION_FLAG) | ||
| 43 | #define AV1B_OBU_HAS_SIZE_FIELD 1 | ||
| 44 | #define AV1F_OBU_HAS_SIZE_FIELD (1u << AV1B_OBU_HAS_SIZE_FIELD) | ||
| 45 | #define AV1B_OBU_RESERVED_1BIT 0 | ||
| 46 | #define AV1F_OBU_RESERVED_1BIT (1u << AV1B_OBU_RESERVED_1BIT) | ||
| 47 | |||
| 48 | #define AV1B_AGGR_HDR_FRAG_CONT 7 | ||
| 49 | #define AV1F_AGGR_HDR_FRAG_CONT (1u << AV1B_AGGR_HDR_FRAG_CONT) | ||
| 50 | #define AV1B_AGGR_HDR_LAST_FRAG 6 | ||
| 51 | #define AV1F_AGGR_HDR_LAST_FRAG (1u << AV1B_AGGR_HDR_LAST_FRAG) | ||
| 52 | #define AV1S_AGGR_HDR_NUM_OBUS 4 | ||
| 53 | #define AV1M_AGGR_HDR_NUM_OBUS 3 | ||
| 54 | #define AV1B_AGGR_HDR_FIRST_PKT 3 | ||
| 55 | #define AV1F_AGGR_HDR_FIRST_PKT (1u << AV1B_AGGR_HDR_FIRST_PKT) | ||
| 56 | |||
| 57 | /// calculate number of required LEB bytes for the given length | ||
| 58 | ✗ | static inline unsigned int calc_leb_size(uint32_t length) { | |
| 59 | ✗ | unsigned int num_lebs = 0; | |
| 60 | do { | ||
| 61 | ✗ | num_lebs++; | |
| 62 | ✗ | length >>= 7; | |
| 63 | ✗ | } while (length); | |
| 64 | ✗ | return num_lebs; | |
| 65 | } | ||
| 66 | |||
| 67 | /// write out variable number of LEB bytes for the given length | ||
| 68 | ✗ | static inline unsigned int write_leb(uint8_t *lebptr, uint32_t length) { | |
| 69 | ✗ | unsigned int num_lebs = 0; | |
| 70 | do { | ||
| 71 | ✗ | num_lebs++; | |
| 72 | ✗ | if (length < 0x80) { | |
| 73 | ✗ | *lebptr = length; | |
| 74 | ✗ | break; | |
| 75 | } | ||
| 76 | ✗ | *lebptr++ = length | 0x80; // no need to mask out | |
| 77 | ✗ | length >>= 7; | |
| 78 | } while (1); | ||
| 79 | ✗ | return num_lebs; | |
| 80 | } | ||
| 81 | |||
| 82 | /// write out fixed number of LEB bytes (may have "unused" bytes) | ||
| 83 | ✗ | static inline void write_leb_n(uint8_t *lebptr, uint32_t length, unsigned int num_lebs) { | |
| 84 | ✗ | for (int i = 0; i < num_lebs; i++) { | |
| 85 | ✗ | if (i == num_lebs - 1) { | |
| 86 | ✗ | *lebptr = length & 0x7f; | |
| 87 | } else { | ||
| 88 | ✗ | *lebptr++ = length | 0x80; // no need to mask out | |
| 89 | } | ||
| 90 | ✗ | length >>= 7; | |
| 91 | } | ||
| 92 | ✗ | } | |
| 93 | |||
| 94 | /// securely parse LEB bytes and return the resulting encoded length | ||
| 95 | ✗ | static inline unsigned int parse_leb(void *logctx, const uint8_t *buf_ptr, | |
| 96 | uint32_t buffer_size, uint32_t *obu_size) { | ||
| 97 | uint8_t leb128; | ||
| 98 | ✗ | unsigned int num_lebs = 0; | |
| 99 | ✗ | *obu_size = 0; | |
| 100 | do { | ||
| 101 | uint32_t leb7; | ||
| 102 | ✗ | if (!buffer_size) { | |
| 103 | ✗ | av_log(logctx, AV_LOG_ERROR, "AV1: Out of data in OBU size field AV1 RTP packet\n"); | |
| 104 | ✗ | return 0; | |
| 105 | } | ||
| 106 | ✗ | leb128 = *buf_ptr++; | |
| 107 | ✗ | leb7 = leb128 & 0x7f; | |
| 108 | ✗ | buffer_size--; | |
| 109 | /* AV1 spec says that the maximum value returned from leb128 must fit in | ||
| 110 | * 32 bits, so if the next byte will shift data out, we have some kind | ||
| 111 | * of violation here. It is legal, though, to have the most significant | ||
| 112 | * bytes with all zero bits (in the lower 7 bits). */ | ||
| 113 | ✗ | if (((num_lebs == 4) && (leb7 >= 0x10)) || ((num_lebs > 4) && leb7)) { | |
| 114 | ✗ | av_log(logctx, AV_LOG_ERROR, "AV1: OBU size field exceeds 32 bit in AV1 RTP packet\n"); | |
| 115 | ✗ | return 0; | |
| 116 | } | ||
| 117 | ✗ | if ((num_lebs == 7) && (leb128 >= 0x80)) { | |
| 118 | /* leb128 is defined to be up to 8 bytes (why???), 8th byte MUST NOT | ||
| 119 | * indicate continuation */ | ||
| 120 | ✗ | av_log(logctx, AV_LOG_ERROR, "AV1: OBU size field consists of too many bytes in AV1 RTP packet\n"); | |
| 121 | ✗ | return 0; | |
| 122 | } | ||
| 123 | // shifts >= 32 are undefined in C! | ||
| 124 | ✗ | if (num_lebs <= 4) { | |
| 125 | ✗ | *obu_size |= leb7 << (7 * num_lebs); | |
| 126 | } | ||
| 127 | ✗ | num_lebs++; | |
| 128 | ✗ | } while (leb128 >= 0x80); | |
| 129 | ✗ | return num_lebs; | |
| 130 | } | ||
| 131 | |||
| 132 | #endif /* AVFORMAT_RTP_AV1_H */ | ||
| 133 |