/* * 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" /** 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 { 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; vpc->v.parse_only = 1; init_get_bits(&gb, buf, buf_size * 8); 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 (avctx->ticks_per_frame > 1){ // process pulldown flags s->repeat_pict = 1; // Pulldown flags are only valid when 'broadcast' has been set. // So ticks_per_frame will be 2 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; } if (avctx->framerate.num) avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1})); } 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 int vc1_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size) { int i; uint32_t state= -1; int charged=0; for(i=0; i<buf_size; i++){ state= (state<<8) | buf[i]; if(IS_MARKER(state)){ if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){ charged=1; }else if(charged){ return i-3; } } } return 0; } 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->prev_start_code = 0; vpc->bytes_to_skip = 0; vpc->unesc_index = 0; vpc->search_state = NO_MATCH; return ff_vc1_init_common(&vpc->v); } 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, .split = vc1_split, };