| 1 | /* |
| 2 | * VC-1 and WMV3 parser |
| 3 | * Copyright (c) 2006-2007 Konstantin Shishkov |
| 4 | * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer |
| 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 | * VC-1 and WMV3 parser |
| 26 | */ |
| 27 | |
| 28 | #include "libavutil/attributes.h" |
| 29 | #include "parser.h" |
| 30 | #include "vc1.h" |
| 31 | #include "get_bits.h" |
| 32 | |
| 33 | /** The maximum number of bytes of a sequence, entry point or |
| 34 | * frame header whose values we pay any attention to */ |
| 35 | #define UNESCAPED_THRESHOLD 37 |
| 36 | |
| 37 | /** The maximum number of bytes of a sequence, entry point or |
| 38 | * frame header which must be valid memory (because they are |
| 39 | * used to update the bitstream cache in skip_bits() calls) |
| 40 | */ |
| 41 | #define UNESCAPED_LIMIT 144 |
| 42 | |
| 43 | typedef enum { |
| 44 | NO_MATCH, |
| 45 | ONE_ZERO, |
| 46 | TWO_ZEROS, |
| 47 | ONE |
| 48 | } VC1ParseSearchState; |
| 49 | |
| 50 | typedef struct { |
| 51 | ParseContext pc; |
| 52 | VC1Context v; |
| 53 | uint8_t prev_start_code; |
| 54 | size_t bytes_to_skip; |
| 55 | uint8_t unesc_buffer[UNESCAPED_LIMIT]; |
| 56 | size_t unesc_index; |
| 57 | VC1ParseSearchState search_state; |
| 58 | } VC1ParseContext; |
| 59 | |
| 60 | static void vc1_extract_header(AVCodecParserContext *s, AVCodecContext *avctx, |
| 61 | const uint8_t *buf, int buf_size) |
| 62 | { |
| 63 | /* Parse the header we just finished unescaping */ |
| 64 | VC1ParseContext *vpc = s->priv_data; |
| 65 | GetBitContext gb; |
| 66 | int ret; |
| 67 | vpc->v.s.avctx = avctx; |
| 68 | vpc->v.parse_only = 1; |
| 69 | init_get_bits(&gb, buf, buf_size * 8); |
| 70 | switch (vpc->prev_start_code) { |
| 71 | case VC1_CODE_SEQHDR & 0xFF: |
| 72 | ff_vc1_decode_sequence_header(avctx, &vpc->v, &gb); |
| 73 | break; |
| 74 | case VC1_CODE_ENTRYPOINT & 0xFF: |
| 75 | ff_vc1_decode_entry_point(avctx, &vpc->v, &gb); |
| 76 | break; |
| 77 | case VC1_CODE_FRAME & 0xFF: |
| 78 | if(vpc->v.profile < PROFILE_ADVANCED) |
| 79 | ret = ff_vc1_parse_frame_header (&vpc->v, &gb); |
| 80 | else |
| 81 | ret = ff_vc1_parse_frame_header_adv(&vpc->v, &gb); |
| 82 | |
| 83 | if (ret < 0) |
| 84 | break; |
| 85 | |
| 86 | /* keep AV_PICTURE_TYPE_BI internal to VC1 */ |
| 87 | if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI) |
| 88 | s->pict_type = AV_PICTURE_TYPE_B; |
| 89 | else |
| 90 | s->pict_type = vpc->v.s.pict_type; |
| 91 | |
| 92 | if (avctx->ticks_per_frame > 1){ |
| 93 | // process pulldown flags |
| 94 | s->repeat_pict = 1; |
| 95 | // Pulldown flags are only valid when 'broadcast' has been set. |
| 96 | // So ticks_per_frame will be 2 |
| 97 | if (vpc->v.rff){ |
| 98 | // repeat field |
| 99 | s->repeat_pict = 2; |
| 100 | }else if (vpc->v.rptfrm){ |
| 101 | // repeat frames |
| 102 | s->repeat_pict = vpc->v.rptfrm * 2 + 1; |
| 103 | } |
| 104 | }else{ |
| 105 | s->repeat_pict = 0; |
| 106 | } |
| 107 | |
| 108 | if (vpc->v.broadcast && vpc->v.interlace && !vpc->v.psf) |
| 109 | s->field_order = vpc->v.tff ? AV_FIELD_TT : AV_FIELD_BB; |
| 110 | else |
| 111 | s->field_order = AV_FIELD_PROGRESSIVE; |
| 112 | |
| 113 | break; |
| 114 | } |
| 115 | } |
| 116 | |
| 117 | static int vc1_parse(AVCodecParserContext *s, |
| 118 | AVCodecContext *avctx, |
| 119 | const uint8_t **poutbuf, int *poutbuf_size, |
| 120 | const uint8_t *buf, int buf_size) |
| 121 | { |
| 122 | /* Here we do the searching for frame boundaries and headers at |
| 123 | * the same time. Only a minimal amount at the start of each |
| 124 | * header is unescaped. */ |
| 125 | VC1ParseContext *vpc = s->priv_data; |
| 126 | int pic_found = vpc->pc.frame_start_found; |
| 127 | uint8_t *unesc_buffer = vpc->unesc_buffer; |
| 128 | size_t unesc_index = vpc->unesc_index; |
| 129 | VC1ParseSearchState search_state = vpc->search_state; |
| 130 | int start_code_found = 0; |
| 131 | int next = END_NOT_FOUND; |
| 132 | int i = vpc->bytes_to_skip; |
| 133 | |
| 134 | if (pic_found && buf_size == 0) { |
| 135 | /* EOF considered as end of frame */ |
| 136 | memset(unesc_buffer + unesc_index, 0, UNESCAPED_THRESHOLD - unesc_index); |
| 137 | vc1_extract_header(s, avctx, unesc_buffer, unesc_index); |
| 138 | next = 0; |
| 139 | } |
| 140 | while (i < buf_size) { |
| 141 | uint8_t b; |
| 142 | start_code_found = 0; |
| 143 | while (i < buf_size && unesc_index < UNESCAPED_THRESHOLD) { |
| 144 | b = buf[i++]; |
| 145 | unesc_buffer[unesc_index++] = b; |
| 146 | if (search_state <= ONE_ZERO) |
| 147 | search_state = b ? NO_MATCH : search_state + 1; |
| 148 | else if (search_state == TWO_ZEROS) { |
| 149 | if (b == 1) |
| 150 | search_state = ONE; |
| 151 | else if (b > 1) { |
| 152 | if (b == 3) |
| 153 | unesc_index--; // swallow emulation prevention byte |
| 154 | search_state = NO_MATCH; |
| 155 | } |
| 156 | } |
| 157 | else { // search_state == ONE |
| 158 | // Header unescaping terminates early due to detection of next start code |
| 159 | search_state = NO_MATCH; |
| 160 | start_code_found = 1; |
| 161 | break; |
| 162 | } |
| 163 | } |
| 164 | if ((s->flags & PARSER_FLAG_COMPLETE_FRAMES) && |
| 165 | unesc_index >= UNESCAPED_THRESHOLD && |
| 166 | vpc->prev_start_code == (VC1_CODE_FRAME & 0xFF)) |
| 167 | { |
| 168 | // No need to keep scanning the rest of the buffer for |
| 169 | // start codes if we know it contains a complete frame and |
| 170 | // we've already unescaped all we need of the frame header |
| 171 | vc1_extract_header(s, avctx, unesc_buffer, unesc_index); |
| 172 | break; |
| 173 | } |
| 174 | if (unesc_index >= UNESCAPED_THRESHOLD && !start_code_found) { |
| 175 | while (i < buf_size) { |
| 176 | if (search_state == NO_MATCH) { |
| 177 | i += vpc->v.vc1dsp.startcode_find_candidate(buf + i, buf_size - i); |
| 178 | if (i < buf_size) { |
| 179 | search_state = ONE_ZERO; |
| 180 | } |
| 181 | i++; |
| 182 | } else { |
| 183 | b = buf[i++]; |
| 184 | if (search_state == ONE_ZERO) |
| 185 | search_state = b ? NO_MATCH : TWO_ZEROS; |
| 186 | else if (search_state == TWO_ZEROS) { |
| 187 | if (b >= 1) |
| 188 | search_state = b == 1 ? ONE : NO_MATCH; |
| 189 | } |
| 190 | else { // search_state == ONE |
| 191 | search_state = NO_MATCH; |
| 192 | start_code_found = 1; |
| 193 | break; |
| 194 | } |
| 195 | } |
| 196 | } |
| 197 | } |
| 198 | if (start_code_found) { |
| 199 | vc1_extract_header(s, avctx, unesc_buffer, unesc_index); |
| 200 | |
| 201 | vpc->prev_start_code = b; |
| 202 | unesc_index = 0; |
| 203 | |
| 204 | if (!(s->flags & PARSER_FLAG_COMPLETE_FRAMES)) { |
| 205 | if (!pic_found && (b == (VC1_CODE_FRAME & 0xFF) || b == (VC1_CODE_FIELD & 0xFF))) { |
| 206 | pic_found = 1; |
| 207 | } |
| 208 | else if (pic_found && b != (VC1_CODE_FIELD & 0xFF) && b != (VC1_CODE_SLICE & 0xFF)) { |
| 209 | next = i - 4; |
| 210 | pic_found = b == (VC1_CODE_FRAME & 0xFF); |
| 211 | break; |
| 212 | } |
| 213 | } |
| 214 | } |
| 215 | } |
| 216 | |
| 217 | vpc->pc.frame_start_found = pic_found; |
| 218 | vpc->unesc_index = unesc_index; |
| 219 | vpc->search_state = search_state; |
| 220 | |
| 221 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { |
| 222 | next = buf_size; |
| 223 | } else { |
| 224 | if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) { |
| 225 | vpc->bytes_to_skip = 0; |
| 226 | *poutbuf = NULL; |
| 227 | *poutbuf_size = 0; |
| 228 | return buf_size; |
| 229 | } |
| 230 | } |
| 231 | |
| 232 | /* If we return with a valid pointer to a combined frame buffer |
| 233 | * then on the next call then we'll have been unhelpfully rewound |
| 234 | * by up to 4 bytes (depending upon whether the start code |
| 235 | * overlapped the input buffer, and if so by how much). We don't |
| 236 | * want this: it will either cause spurious second detections of |
| 237 | * the start code we've already seen, or cause extra bytes to be |
| 238 | * inserted at the start of the unescaped buffer. */ |
| 239 | vpc->bytes_to_skip = 4; |
| 240 | if (next < 0 && next != END_NOT_FOUND) |
| 241 | vpc->bytes_to_skip += next; |
| 242 | |
| 243 | *poutbuf = buf; |
| 244 | *poutbuf_size = buf_size; |
| 245 | return next; |
| 246 | } |
| 247 | |
| 248 | static int vc1_split(AVCodecContext *avctx, |
| 249 | const uint8_t *buf, int buf_size) |
| 250 | { |
| 251 | int i; |
| 252 | uint32_t state= -1; |
| 253 | int charged=0; |
| 254 | |
| 255 | for(i=0; i<buf_size; i++){ |
| 256 | state= (state<<8) | buf[i]; |
| 257 | if(IS_MARKER(state)){ |
| 258 | if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){ |
| 259 | charged=1; |
| 260 | }else if(charged){ |
| 261 | return i-3; |
| 262 | } |
| 263 | } |
| 264 | } |
| 265 | return 0; |
| 266 | } |
| 267 | |
| 268 | static av_cold int vc1_parse_init(AVCodecParserContext *s) |
| 269 | { |
| 270 | VC1ParseContext *vpc = s->priv_data; |
| 271 | vpc->v.s.slice_context_count = 1; |
| 272 | vpc->v.first_pic_header_flag = 1; |
| 273 | vpc->prev_start_code = 0; |
| 274 | vpc->bytes_to_skip = 0; |
| 275 | vpc->unesc_index = 0; |
| 276 | vpc->search_state = NO_MATCH; |
| 277 | return ff_vc1_init_common(&vpc->v); |
| 278 | } |
| 279 | |
| 280 | AVCodecParser ff_vc1_parser = { |
| 281 | .codec_ids = { AV_CODEC_ID_VC1 }, |
| 282 | .priv_data_size = sizeof(VC1ParseContext), |
| 283 | .parser_init = vc1_parse_init, |
| 284 | .parser_parse = vc1_parse, |
| 285 | .parser_close = ff_parse_close, |
| 286 | .split = vc1_split, |
| 287 | }; |