| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * GIF parser | ||
| 3 | * Copyright (c) 2018 Paul B Mahol | ||
| 4 | * | ||
| 5 | * This file is part of FFmpeg. | ||
| 6 | * | ||
| 7 | * FFmpeg is free software; you can redistribute it and/or | ||
| 8 | * modify it under the terms of the GNU Lesser General Public | ||
| 9 | * License as published by the Free Software Foundation; either | ||
| 10 | * version 2.1 of the License, or (at your option) any later version. | ||
| 11 | * | ||
| 12 | * FFmpeg is distributed in the hope that it will be useful, | ||
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| 15 | * Lesser General Public License for more details. | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU Lesser General Public | ||
| 18 | * License along with FFmpeg; if not, write to the Free Software | ||
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
| 20 | */ | ||
| 21 | |||
| 22 | /** | ||
| 23 | * @file | ||
| 24 | * GIF parser | ||
| 25 | */ | ||
| 26 | |||
| 27 | #include "libavutil/bswap.h" | ||
| 28 | #include "libavutil/common.h" | ||
| 29 | |||
| 30 | #include "gif.h" | ||
| 31 | #include "parser.h" | ||
| 32 | |||
| 33 | typedef enum GIFParseStates { | ||
| 34 | GIF_HEADER = 1, | ||
| 35 | GIF_EXTENSION, | ||
| 36 | GIF_EXTENSION_BLOCK, | ||
| 37 | GIF_IMAGE, | ||
| 38 | GIF_IMAGE_BLOCK, | ||
| 39 | } gif_states; | ||
| 40 | |||
| 41 | typedef struct GIFParseContext { | ||
| 42 | ParseContext pc; | ||
| 43 | unsigned found_sig; | ||
| 44 | int found_start; | ||
| 45 | int found_end; | ||
| 46 | int index; | ||
| 47 | int state; | ||
| 48 | int gct_flag; | ||
| 49 | int gct_size; | ||
| 50 | int block_size; | ||
| 51 | int etype; | ||
| 52 | int delay; | ||
| 53 | } GIFParseContext; | ||
| 54 | |||
| 55 | ✗ | static int gif_find_frame_end(GIFParseContext *g, const uint8_t *buf, | |
| 56 | int buf_size, void *logctx) | ||
| 57 | { | ||
| 58 | ✗ | int index, next = END_NOT_FOUND; | |
| 59 | |||
| 60 | ✗ | for (index = 0; index < buf_size; index++) { | |
| 61 | ✗ | if (!g->state) { | |
| 62 | ✗ | if (!memcmp(buf + index, gif87a_sig, 6) || | |
| 63 | ✗ | !memcmp(buf + index, gif89a_sig, 6)) { | |
| 64 | ✗ | g->state = GIF_HEADER; | |
| 65 | ✗ | g->found_sig++; | |
| 66 | ✗ | } else if (buf[index] == GIF_EXTENSION_INTRODUCER) { | |
| 67 | ✗ | g->state = GIF_EXTENSION; | |
| 68 | ✗ | g->found_start = 1; | |
| 69 | ✗ | } else if (buf[index] == GIF_IMAGE_SEPARATOR) { | |
| 70 | ✗ | g->state = GIF_IMAGE; | |
| 71 | ✗ | } else if (buf[index] == GIF_TRAILER) { | |
| 72 | ✗ | g->state = 0; | |
| 73 | ✗ | g->found_end = 1; | |
| 74 | ✗ | g->found_sig = 0; | |
| 75 | } else { | ||
| 76 | ✗ | g->found_sig = 0; | |
| 77 | } | ||
| 78 | } | ||
| 79 | |||
| 80 | ✗ | if (g->state == GIF_HEADER) { | |
| 81 | ✗ | if (g->index == 10) { | |
| 82 | ✗ | g->gct_flag = !!(buf[index] & 0x80); | |
| 83 | ✗ | g->gct_size = 3 * (1 << ((buf[index] & 0x07) + 1)); | |
| 84 | } | ||
| 85 | ✗ | if (g->index >= 12 + g->gct_flag * g->gct_size) { | |
| 86 | ✗ | g->state = 0; | |
| 87 | ✗ | g->index = 0; | |
| 88 | ✗ | g->gct_flag = 0; | |
| 89 | ✗ | g->gct_size = 0; | |
| 90 | ✗ | continue; | |
| 91 | } | ||
| 92 | ✗ | g->index++; | |
| 93 | ✗ | } else if (g->state == GIF_EXTENSION) { | |
| 94 | ✗ | if (g->found_start && g->found_end && g->found_sig) { | |
| 95 | ✗ | next = index; | |
| 96 | ✗ | g->found_start = 0; | |
| 97 | ✗ | g->found_end = 0; | |
| 98 | ✗ | g->index = 0; | |
| 99 | ✗ | g->gct_flag = 0; | |
| 100 | ✗ | g->gct_size = 0; | |
| 101 | ✗ | g->state = 0; | |
| 102 | ✗ | break; | |
| 103 | } | ||
| 104 | ✗ | if (g->index == 1) { | |
| 105 | ✗ | g->etype = buf[index]; | |
| 106 | } | ||
| 107 | ✗ | if (g->index >= 2) { | |
| 108 | ✗ | g->block_size = buf[index]; | |
| 109 | ✗ | g->index = 0; | |
| 110 | ✗ | g->state = GIF_EXTENSION_BLOCK; | |
| 111 | ✗ | continue; | |
| 112 | } | ||
| 113 | ✗ | g->index++; | |
| 114 | ✗ | } else if (g->state == GIF_IMAGE_BLOCK) { | |
| 115 | ✗ | if (!g->index) | |
| 116 | ✗ | g->block_size = buf[index]; | |
| 117 | ✗ | if (g->index >= g->block_size) { | |
| 118 | ✗ | g->index = 0; | |
| 119 | ✗ | if (!g->block_size) { | |
| 120 | ✗ | g->state = 0; | |
| 121 | ✗ | g->found_end = 1; | |
| 122 | } | ||
| 123 | ✗ | continue; | |
| 124 | } | ||
| 125 | ✗ | g->index++; | |
| 126 | ✗ | } else if (g->state == GIF_EXTENSION_BLOCK) { | |
| 127 | ✗ | if (g->etype == GIF_GCE_EXT_LABEL) { | |
| 128 | ✗ | if (g->index == 0) | |
| 129 | ✗ | g->delay = 0; | |
| 130 | ✗ | if (g->index >= 1 && g->index <= 2) { | |
| 131 | ✗ | g->delay |= buf[index] << (8 * (g->index - 1)); | |
| 132 | } | ||
| 133 | } | ||
| 134 | ✗ | if (g->index >= g->block_size) { | |
| 135 | ✗ | g->block_size = buf[index]; | |
| 136 | ✗ | g->index = 0; | |
| 137 | ✗ | if (!g->block_size) | |
| 138 | ✗ | g->state = 0; | |
| 139 | ✗ | continue; | |
| 140 | } | ||
| 141 | ✗ | g->index++; | |
| 142 | ✗ | } else if (g->state == GIF_IMAGE) { | |
| 143 | ✗ | if (g->index == 8) { | |
| 144 | ✗ | g->gct_flag = !!(buf[index] & 0x80); | |
| 145 | ✗ | g->gct_size = 3 * (1 << ((buf[index] & 0x07) + 1)); | |
| 146 | } | ||
| 147 | ✗ | if (g->index >= 10 + g->gct_flag * g->gct_size) { | |
| 148 | ✗ | g->state = GIF_IMAGE_BLOCK; | |
| 149 | ✗ | g->index = 0; | |
| 150 | ✗ | g->gct_flag = 0; | |
| 151 | ✗ | g->gct_size = 0; | |
| 152 | ✗ | continue; | |
| 153 | } | ||
| 154 | ✗ | g->index++; | |
| 155 | } | ||
| 156 | } | ||
| 157 | |||
| 158 | ✗ | return next; | |
| 159 | } | ||
| 160 | |||
| 161 | ✗ | static int gif_parse(AVCodecParserContext *s, AVCodecContext *avctx, | |
| 162 | const uint8_t **poutbuf, int *poutbuf_size, | ||
| 163 | const uint8_t *buf, int buf_size) | ||
| 164 | { | ||
| 165 | ✗ | GIFParseContext *g = s->priv_data; | |
| 166 | int next; | ||
| 167 | |||
| 168 | ✗ | next = gif_find_frame_end(g, buf, buf_size, avctx); | |
| 169 | ✗ | if (ff_combine_frame(&g->pc, next, &buf, &buf_size) < 0) { | |
| 170 | ✗ | *poutbuf = NULL; | |
| 171 | ✗ | *poutbuf_size = 0; | |
| 172 | ✗ | return buf_size; | |
| 173 | } | ||
| 174 | |||
| 175 | ✗ | s->duration = g->delay; | |
| 176 | |||
| 177 | ✗ | *poutbuf = buf; | |
| 178 | ✗ | *poutbuf_size = buf_size; | |
| 179 | ✗ | return next; | |
| 180 | } | ||
| 181 | |||
| 182 | const AVCodecParser ff_gif_parser = { | ||
| 183 | .codec_ids = { AV_CODEC_ID_GIF }, | ||
| 184 | .priv_data_size = sizeof(GIFParseContext), | ||
| 185 | .parser_parse = gif_parse, | ||
| 186 | .parser_close = ff_parse_close, | ||
| 187 | }; | ||
| 188 |