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libavcodec/vc1_parser.c

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00001 /*
00002  * VC-1 and WMV3 parser
00003  * Copyright (c) 2006-2007 Konstantin Shishkov
00004  * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00028 #include "parser.h"
00029 #include "vc1.h"
00030 #include "get_bits.h"
00031 
00032 typedef struct {
00033     ParseContext pc;
00034     VC1Context v;
00035 } VC1ParseContext;
00036 
00037 static void vc1_extract_headers(AVCodecParserContext *s, AVCodecContext *avctx,
00038                                 const uint8_t *buf, int buf_size)
00039 {
00040     VC1ParseContext *vpc = s->priv_data;
00041     GetBitContext gb;
00042     const uint8_t *start, *end, *next;
00043     uint8_t *buf2 = av_mallocz(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
00044 
00045     vpc->v.s.avctx = avctx;
00046     vpc->v.parse_only = 1;
00047     next = buf;
00048 
00049     for(start = buf, end = buf + buf_size; next < end; start = next){
00050         int buf2_size, size;
00051 
00052         next = find_next_marker(start + 4, end);
00053         size = next - start - 4;
00054         buf2_size = vc1_unescape_buffer(start + 4, size, buf2);
00055         init_get_bits(&gb, buf2, buf2_size * 8);
00056         if(size <= 0) continue;
00057         switch(AV_RB32(start)){
00058         case VC1_CODE_SEQHDR:
00059             vc1_decode_sequence_header(avctx, &vpc->v, &gb);
00060             break;
00061         case VC1_CODE_ENTRYPOINT:
00062             vc1_decode_entry_point(avctx, &vpc->v, &gb);
00063             break;
00064         case VC1_CODE_FRAME:
00065             if(vpc->v.profile < PROFILE_ADVANCED)
00066                 vc1_parse_frame_header    (&vpc->v, &gb);
00067             else
00068                 vc1_parse_frame_header_adv(&vpc->v, &gb);
00069 
00070             /* keep FF_BI_TYPE internal to VC1 */
00071             if (vpc->v.s.pict_type == FF_BI_TYPE)
00072                 s->pict_type = FF_B_TYPE;
00073             else
00074                 s->pict_type = vpc->v.s.pict_type;
00075 
00076             break;
00077         }
00078     }
00079 
00080     av_free(buf2);
00081 }
00082 
00087 static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,
00088                                int buf_size) {
00089     int pic_found, i;
00090     uint32_t state;
00091 
00092     pic_found= pc->frame_start_found;
00093     state= pc->state;
00094 
00095     i=0;
00096     if(!pic_found){
00097         for(i=0; i<buf_size; i++){
00098             state= (state<<8) | buf[i];
00099             if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){
00100                 i++;
00101                 pic_found=1;
00102                 break;
00103             }
00104         }
00105     }
00106 
00107     if(pic_found){
00108         /* EOF considered as end of frame */
00109         if (buf_size == 0)
00110             return 0;
00111         for(; i<buf_size; i++){
00112             state= (state<<8) | buf[i];
00113             if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){
00114                 pc->frame_start_found=0;
00115                 pc->state=-1;
00116                 return i-3;
00117             }
00118         }
00119     }
00120     pc->frame_start_found= pic_found;
00121     pc->state= state;
00122     return END_NOT_FOUND;
00123 }
00124 
00125 static int vc1_parse(AVCodecParserContext *s,
00126                            AVCodecContext *avctx,
00127                            const uint8_t **poutbuf, int *poutbuf_size,
00128                            const uint8_t *buf, int buf_size)
00129 {
00130     VC1ParseContext *vpc = s->priv_data;
00131     int next;
00132 
00133     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
00134         next= buf_size;
00135     }else{
00136         next= vc1_find_frame_end(&vpc->pc, buf, buf_size);
00137 
00138         if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) {
00139             *poutbuf = NULL;
00140             *poutbuf_size = 0;
00141             return buf_size;
00142         }
00143     }
00144 
00145     vc1_extract_headers(s, avctx, buf, buf_size);
00146 
00147     *poutbuf = buf;
00148     *poutbuf_size = buf_size;
00149     return next;
00150 }
00151 
00152 static int vc1_split(AVCodecContext *avctx,
00153                            const uint8_t *buf, int buf_size)
00154 {
00155     int i;
00156     uint32_t state= -1;
00157     int charged=0;
00158 
00159     for(i=0; i<buf_size; i++){
00160         state= (state<<8) | buf[i];
00161         if(IS_MARKER(state)){
00162             if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){
00163                 charged=1;
00164             }else if(charged){
00165                 return i-3;
00166             }
00167         }
00168     }
00169     return 0;
00170 }
00171 
00172 AVCodecParser vc1_parser = {
00173     { CODEC_ID_VC1 },
00174     sizeof(VC1ParseContext),
00175     NULL,
00176     vc1_parse,
00177     ff_parse1_close,
00178     vc1_split,
00179 };

Generated on Fri Sep 16 2011 17:17:45 for FFmpeg by  doxygen 1.7.1