libavcodec/vc1_parser.c

   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 libavcodec/vc1_parser.c
  25  * VC-1 and WMV3 parser
  26  */
  27
  28 #include "parser.h"
  29 #include "vc1.h"
  30 #include "get_bits.h"
  31
  32 typedef struct {
  33     ParseContext pc;
  34     VC1Context v;
  35 } VC1ParseContext;
  36
  37 static void vc1_extract_headers(AVCodecParserContext *s, AVCodecContext *avctx,
  38                                 const uint8_t *buf, int buf_size)
  39 {
  40     VC1ParseContext *vpc = s->priv_data;
  41     GetBitContext gb;
  42     const uint8_t *start, *end, *next;
  43     uint8_t *buf2 = av_mallocz(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
  44
  45     vpc->v.s.avctx = avctx;
  46     vpc->v.parse_only = 1;
  47     next = buf;
  48
  49     for(start = buf, end = buf + buf_size; next < end; start = next){
  50         int buf2_size, size;
  51
  52         next = find_next_marker(start + 4, end);
  53         size = next - start - 4;
  54         buf2_size = vc1_unescape_buffer(start + 4, size, buf2);
  55         init_get_bits(&gb, buf2, buf2_size * 8);
  56         if(size <= 0) continue;
  57         switch(AV_RB32(start)){
  58         case VC1_CODE_SEQHDR:
  59             vc1_decode_sequence_header(avctx, &vpc->v, &gb);
  60             break;
  61         case VC1_CODE_ENTRYPOINT:
  62             vc1_decode_entry_point(avctx, &vpc->v, &gb);
  63             break;
  64         case VC1_CODE_FRAME:
  65             if(vpc->v.profile < PROFILE_ADVANCED)
  66                 vc1_parse_frame_header    (&vpc->v, &gb);
  67             else
  68                 vc1_parse_frame_header_adv(&vpc->v, &gb);
  69
  70             /* keep FF_BI_TYPE internal to VC1 */
  71             if (vpc->v.s.pict_type == FF_BI_TYPE)
  72                 s->pict_type = FF_B_TYPE;
  73             else
  74                 s->pict_type = vpc->v.s.pict_type;
  75
  76             break;
  77         }
  78     }
  79
  80     av_free(buf2);
  81 }
  82
  83 /**
  84  * finds the end of the current frame in the bitstream.
  85  * @return the position of the first byte of the next frame, or -1
  86  */
  87 static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,
  88                                int buf_size) {
  89     int pic_found, i;
  90     uint32_t state;
  91
  92     pic_found= pc->frame_start_found;
  93     state= pc->state;
  94
  95     i=0;
  96     if(!pic_found){
  97         for(i=0; i<buf_size; i++){
  98             state= (state<<8) | buf[i];
  99             if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){
 100                 i++;
 101                 pic_found=1;
 102                 break;
 103             }
 104         }
 105     }
 106
 107     if(pic_found){
 108         /* EOF considered as end of frame */
 109         if (buf_size == 0)
 110             return 0;
 111         for(; i<buf_size; i++){
 112             state= (state<<8) | buf[i];
 113             if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){
 114                 pc->frame_start_found=0;
 115                 pc->state=-1;
 116                 return i-3;
 117             }
 118         }
 119     }
 120     pc->frame_start_found= pic_found;
 121     pc->state= state;
 122     return END_NOT_FOUND;
 123 }
 124
 125 static int vc1_parse(AVCodecParserContext *s,
 126                            AVCodecContext *avctx,
 127                            const uint8_t **poutbuf, int *poutbuf_size,
 128                            const uint8_t *buf, int buf_size)
 129 {
 130     VC1ParseContext *vpc = s->priv_data;
 131     int next;
 132
 133     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
 134         next= buf_size;
 135     }else{
 136         next= vc1_find_frame_end(&vpc->pc, buf, buf_size);
 137
 138         if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) {
 139             *poutbuf = NULL;
 140             *poutbuf_size = 0;
 141             return buf_size;
 142         }
 143     }
 144
 145     vc1_extract_headers(s, avctx, buf, buf_size);
 146
 147     *poutbuf = buf;
 148     *poutbuf_size = buf_size;
 149     return next;
 150 }
 151
 152 static int vc1_split(AVCodecContext *avctx,
 153                            const uint8_t *buf, int buf_size)
 154 {
 155     int i;
 156     uint32_t state= -1;
 157     int charged=0;
 158
 159     for(i=0; i<buf_size; i++){
 160         state= (state<<8) | buf[i];
 161         if(IS_MARKER(state)){
 162             if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){
 163                 charged=1;
 164             }else if(charged){
 165                 return i-3;
 166             }
 167         }
 168     }
 169     return 0;
 170 }
 171
 172 AVCodecParser vc1_parser = {
 173     { CODEC_ID_VC1 },
 174     sizeof(VC1ParseContext),
 175     NULL,
 176     vc1_parse,
 177     ff_parse1_close,
 178     vc1_split,
 179 };