| /* | |
| * VC-1 and WMV3 parser | |
| * Copyright (c) 2006-2007 Konstantin Shishkov | |
| * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer | |
| * | |
| * This file is part of FFmpeg. | |
| * | |
| * FFmpeg is free software; you can redistribute it and/or | |
| * modify it under the terms of the GNU Lesser General Public | |
| * License as published by the Free Software Foundation; either | |
| * version 2.1 of the License, or (at your option) any later version. | |
| * | |
| * FFmpeg is distributed in the hope that it will be useful, | |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| * Lesser General Public License for more details. | |
| * | |
| * You should have received a copy of the GNU Lesser General Public | |
| * License along with FFmpeg; if not, write to the Free Software | |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
| */ | |
| /** | |
| * @file | |
| * VC-1 and WMV3 parser | |
| */ | |
| #include "libavutil/attributes.h" | |
| #include "parser.h" | |
| #include "vc1.h" | |
| #include "get_bits.h" | |
| #include "vc1dsp.h" | |
| /** The maximum number of bytes of a sequence, entry point or | |
| * frame header whose values we pay any attention to */ | |
| #define UNESCAPED_THRESHOLD 37 | |
| /** The maximum number of bytes of a sequence, entry point or | |
| * frame header which must be valid memory (because they are | |
| * used to update the bitstream cache in skip_bits() calls) | |
| */ | |
| #define UNESCAPED_LIMIT 144 | |
| typedef enum { | |
| NO_MATCH, | |
| ONE_ZERO, | |
| TWO_ZEROS, | |
| ONE | |
| } VC1ParseSearchState; | |
| typedef struct VC1ParseContext { | |
| ParseContext pc; | |
| VC1Context v; | |
| uint8_t prev_start_code; | |
| size_t bytes_to_skip; | |
| uint8_t unesc_buffer[UNESCAPED_LIMIT]; | |
| size_t unesc_index; | |
| VC1ParseSearchState search_state; | |
| } VC1ParseContext; | |
| static void vc1_extract_header(AVCodecParserContext *s, AVCodecContext *avctx, | |
| const uint8_t *buf, int buf_size) | |
| { | |
| /* Parse the header we just finished unescaping */ | |
| VC1ParseContext *vpc = s->priv_data; | |
| GetBitContext gb; | |
| int ret; | |
| vpc->v.s.avctx = avctx; | |
| init_get_bits8(&gb, buf, buf_size); | |
| switch (vpc->prev_start_code) { | |
| case VC1_CODE_SEQHDR & 0xFF: | |
| ff_vc1_decode_sequence_header(avctx, &vpc->v, &gb); | |
| break; | |
| case VC1_CODE_ENTRYPOINT & 0xFF: | |
| ff_vc1_decode_entry_point(avctx, &vpc->v, &gb); | |
| break; | |
| case VC1_CODE_FRAME & 0xFF: | |
| if(vpc->v.profile < PROFILE_ADVANCED) | |
| ret = ff_vc1_parse_frame_header (&vpc->v, &gb); | |
| else | |
| ret = ff_vc1_parse_frame_header_adv(&vpc->v, &gb); | |
| if (ret < 0) | |
| break; | |
| /* keep AV_PICTURE_TYPE_BI internal to VC1 */ | |
| if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI) | |
| s->pict_type = AV_PICTURE_TYPE_B; | |
| else | |
| s->pict_type = vpc->v.s.pict_type; | |
| if (vpc->v.broadcast){ | |
| // process pulldown flags | |
| s->repeat_pict = 1; | |
| // Pulldown flags are only valid when 'broadcast' has been set. | |
| if (vpc->v.rff){ | |
| // repeat field | |
| s->repeat_pict = 2; | |
| }else if (vpc->v.rptfrm){ | |
| // repeat frames | |
| s->repeat_pict = vpc->v.rptfrm * 2 + 1; | |
| } | |
| }else{ | |
| s->repeat_pict = 0; | |
| } | |
| if (vpc->v.broadcast && vpc->v.interlace && !vpc->v.psf) | |
| s->field_order = vpc->v.tff ? AV_FIELD_TT : AV_FIELD_BB; | |
| else | |
| s->field_order = AV_FIELD_PROGRESSIVE; | |
| break; | |
| } | |
| s->format = vpc->v.chromaformat == 1 ? AV_PIX_FMT_YUV420P | |
| : AV_PIX_FMT_NONE; | |
| if (avctx->width && avctx->height) { | |
| s->width = avctx->width; | |
| s->height = avctx->height; | |
| s->coded_width = FFALIGN(avctx->coded_width, 16); | |
| s->coded_height = FFALIGN(avctx->coded_height, 16); | |
| } | |
| } | |
| static int vc1_parse(AVCodecParserContext *s, | |
| AVCodecContext *avctx, | |
| const uint8_t **poutbuf, int *poutbuf_size, | |
| const uint8_t *buf, int buf_size) | |
| { | |
| /* Here we do the searching for frame boundaries and headers at | |
| * the same time. Only a minimal amount at the start of each | |
| * header is unescaped. */ | |
| VC1ParseContext *vpc = s->priv_data; | |
| int pic_found = vpc->pc.frame_start_found; | |
| uint8_t *unesc_buffer = vpc->unesc_buffer; | |
| size_t unesc_index = vpc->unesc_index; | |
| VC1ParseSearchState search_state = vpc->search_state; | |
| int start_code_found = 0; | |
| int next = END_NOT_FOUND; | |
| int i = vpc->bytes_to_skip; | |
| if (pic_found && buf_size == 0) { | |
| /* EOF considered as end of frame */ | |
| memset(unesc_buffer + unesc_index, 0, UNESCAPED_THRESHOLD - unesc_index); | |
| vc1_extract_header(s, avctx, unesc_buffer, unesc_index); | |
| next = 0; | |
| } | |
| while (i < buf_size) { | |
| uint8_t b; | |
| start_code_found = 0; | |
| while (i < buf_size && unesc_index < UNESCAPED_THRESHOLD) { | |
| b = buf[i++]; | |
| unesc_buffer[unesc_index++] = b; | |
| if (search_state <= ONE_ZERO) | |
| search_state = b ? NO_MATCH : search_state + 1; | |
| else if (search_state == TWO_ZEROS) { | |
| if (b == 1) | |
| search_state = ONE; | |
| else if (b > 1) { | |
| if (b == 3) | |
| unesc_index--; // swallow emulation prevention byte | |
| search_state = NO_MATCH; | |
| } | |
| } | |
| else { // search_state == ONE | |
| // Header unescaping terminates early due to detection of next start code | |
| search_state = NO_MATCH; | |
| start_code_found = 1; | |
| break; | |
| } | |
| } | |
| if ((s->flags & PARSER_FLAG_COMPLETE_FRAMES) && | |
| unesc_index >= UNESCAPED_THRESHOLD && | |
| vpc->prev_start_code == (VC1_CODE_FRAME & 0xFF)) | |
| { | |
| // No need to keep scanning the rest of the buffer for | |
| // start codes if we know it contains a complete frame and | |
| // we've already unescaped all we need of the frame header | |
| vc1_extract_header(s, avctx, unesc_buffer, unesc_index); | |
| break; | |
| } | |
| if (unesc_index >= UNESCAPED_THRESHOLD && !start_code_found) { | |
| while (i < buf_size) { | |
| if (search_state == NO_MATCH) { | |
| i += vpc->v.vc1dsp.startcode_find_candidate(buf + i, buf_size - i); | |
| if (i < buf_size) { | |
| search_state = ONE_ZERO; | |
| } | |
| i++; | |
| } else { | |
| b = buf[i++]; | |
| if (search_state == ONE_ZERO) | |
| search_state = b ? NO_MATCH : TWO_ZEROS; | |
| else if (search_state == TWO_ZEROS) { | |
| if (b >= 1) | |
| search_state = b == 1 ? ONE : NO_MATCH; | |
| } | |
| else { // search_state == ONE | |
| search_state = NO_MATCH; | |
| start_code_found = 1; | |
| break; | |
| } | |
| } | |
| } | |
| } | |
| if (start_code_found) { | |
| vc1_extract_header(s, avctx, unesc_buffer, unesc_index); | |
| vpc->prev_start_code = b; | |
| unesc_index = 0; | |
| if (!(s->flags & PARSER_FLAG_COMPLETE_FRAMES)) { | |
| if (!pic_found && (b == (VC1_CODE_FRAME & 0xFF) || b == (VC1_CODE_FIELD & 0xFF))) { | |
| pic_found = 1; | |
| } | |
| else if (pic_found && b != (VC1_CODE_FIELD & 0xFF) && b != (VC1_CODE_SLICE & 0xFF)) { | |
| next = i - 4; | |
| pic_found = b == (VC1_CODE_FRAME & 0xFF); | |
| break; | |
| } | |
| } | |
| } | |
| } | |
| vpc->pc.frame_start_found = pic_found; | |
| vpc->unesc_index = unesc_index; | |
| vpc->search_state = search_state; | |
| if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { | |
| next = buf_size; | |
| } else { | |
| if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) { | |
| vpc->bytes_to_skip = 0; | |
| *poutbuf = NULL; | |
| *poutbuf_size = 0; | |
| return buf_size; | |
| } | |
| } | |
| /* If we return with a valid pointer to a combined frame buffer | |
| * then on the next call then we'll have been unhelpfully rewound | |
| * by up to 4 bytes (depending upon whether the start code | |
| * overlapped the input buffer, and if so by how much). We don't | |
| * want this: it will either cause spurious second detections of | |
| * the start code we've already seen, or cause extra bytes to be | |
| * inserted at the start of the unescaped buffer. */ | |
| vpc->bytes_to_skip = 4; | |
| if (next < 0 && next != END_NOT_FOUND) | |
| vpc->bytes_to_skip += next; | |
| *poutbuf = buf; | |
| *poutbuf_size = buf_size; | |
| return next; | |
| } | |
| static av_cold int vc1_parse_init(AVCodecParserContext *s) | |
| { | |
| VC1ParseContext *vpc = s->priv_data; | |
| vpc->v.s.slice_context_count = 1; | |
| vpc->v.first_pic_header_flag = 1; | |
| vpc->v.parse_only = 1; | |
| vpc->prev_start_code = 0; | |
| vpc->bytes_to_skip = 0; | |
| vpc->unesc_index = 0; | |
| vpc->search_state = NO_MATCH; | |
| ff_vc1dsp_init(&vpc->v.vc1dsp); /* startcode_find_candidate */ | |
| return 0; | |
| } | |
| const AVCodecParser ff_vc1_parser = { | |
| .codec_ids = { AV_CODEC_ID_VC1 }, | |
| .priv_data_size = sizeof(VC1ParseContext), | |
| .parser_init = vc1_parse_init, | |
| .parser_parse = vc1_parse, | |
| .parser_close = ff_parse_close, | |
| }; |