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libavcodec/mjpeg_parser.c

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00001 /*
00002  * MJPEG parser
00003  * Copyright (c) 2000, 2001 Fabrice Bellard
00004  * Copyright (c) 2003 Alex Beregszaszi
00005  * Copyright (c) 2003-2004 Michael Niedermayer
00006  *
00007  * This file is part of FFmpeg.
00008  *
00009  * FFmpeg is free software; you can redistribute it and/or
00010  * modify it under the terms of the GNU Lesser General Public
00011  * License as published by the Free Software Foundation; either
00012  * version 2.1 of the License, or (at your option) any later version.
00013  *
00014  * FFmpeg is distributed in the hope that it will be useful,
00015  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00016  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017  * Lesser General Public License for more details.
00018  *
00019  * You should have received a copy of the GNU Lesser General Public
00020  * License along with FFmpeg; if not, write to the Free Software
00021  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00022  */
00023 
00029 #include "parser.h"
00030 
00031 
00036 static int find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){
00037     int vop_found, i;
00038     uint16_t state;
00039 
00040     vop_found= pc->frame_start_found;
00041     state= pc->state;
00042 
00043     i=0;
00044     if(!vop_found){
00045         for(i=0; i<buf_size; i++){
00046             state= (state<<8) | buf[i];
00047             if(state == 0xFFD8){
00048                 i++;
00049                 vop_found=1;
00050                 break;
00051             }
00052         }
00053     }
00054 
00055     if(vop_found){
00056         /* EOF considered as end of frame */
00057         if (buf_size == 0)
00058             return 0;
00059         for(; i<buf_size; i++){
00060             state= (state<<8) | buf[i];
00061             if(state == 0xFFD8){
00062                 pc->frame_start_found=0;
00063                 pc->state=0;
00064                 return i-1;
00065             }
00066         }
00067     }
00068     pc->frame_start_found= vop_found;
00069     pc->state= state;
00070     return END_NOT_FOUND;
00071 }
00072 
00073 static int jpeg_parse(AVCodecParserContext *s,
00074                       AVCodecContext *avctx,
00075                       const uint8_t **poutbuf, int *poutbuf_size,
00076                       const uint8_t *buf, int buf_size)
00077 {
00078     ParseContext *pc = s->priv_data;
00079     int next;
00080 
00081     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
00082         next= buf_size;
00083     }else{
00084         next= find_frame_end(pc, buf, buf_size);
00085 
00086         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
00087             *poutbuf = NULL;
00088             *poutbuf_size = 0;
00089             return buf_size;
00090         }
00091     }
00092 
00093     *poutbuf = buf;
00094     *poutbuf_size = buf_size;
00095     return next;
00096 }
00097 
00098 
00099 AVCodecParser mjpeg_parser = {
00100     { CODEC_ID_MJPEG },
00101     sizeof(ParseContext),
00102     NULL,
00103     jpeg_parse,
00104     ff_parse_close,
00105 };

Generated on Fri Sep 16 2011 17:17:39 for FFmpeg by  doxygen 1.7.1