/* * MJPEG parser * Copyright (c) 2000, 2001 Fabrice Bellard * Copyright (c) 2003 Alex Beregszaszi * Copyright (c) 2003-2004 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 * MJPEG parser. */ #include "parser.h" typedef struct MJPEGParserContext{ ParseContext pc; int size; }MJPEGParserContext; /** * Find the end of the current frame in the bitstream. * @return the position of the first byte of the next frame, or -1 */ static int find_frame_end(MJPEGParserContext *m, const uint8_t *buf, int buf_size){ ParseContext *pc= &m->pc; int vop_found, i; uint32_t state; vop_found= pc->frame_start_found; state= pc->state; i=0; if(!vop_found){ for(i=0; i<buf_size;){ state= (state<<8) | buf[i]; if(state>=0xFFC00000 && state<=0xFFFEFFFF){ if(state>=0xFFD80000 && state<=0xFFD8FFFF){ i++; vop_found=1; break; }else if(state<0xFFD00000 || state>0xFFD9FFFF){ m->size= (state&0xFFFF)-1; } } if(m->size>0){ int size= FFMIN(buf_size-i, m->size); i+=size; m->size-=size; state=0; continue; }else i++; } } if(vop_found){ /* EOF considered as end of frame */ if (buf_size == 0) return 0; for(; i<buf_size;){ state= (state<<8) | buf[i]; if(state>=0xFFC00000 && state<=0xFFFEFFFF){ if(state>=0xFFD80000 && state<=0xFFD8FFFF){ pc->frame_start_found=0; pc->state=0; return i-3; } else if(state<0xFFD00000 || state>0xFFD9FFFF){ m->size= (state&0xFFFF)-1; } } if(m->size>0){ int size= FFMIN(buf_size-i, m->size); i+=size; m->size-=size; state=0; continue; }else i++; } } pc->frame_start_found= vop_found; pc->state= state; return END_NOT_FOUND; } static int jpeg_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size) { MJPEGParserContext *m = s->priv_data; ParseContext *pc = &m->pc; int next; if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ next= buf_size; }else{ next= find_frame_end(m, buf, buf_size); if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { *poutbuf = NULL; *poutbuf_size = 0; return buf_size; } } *poutbuf = buf; *poutbuf_size = buf_size; return next; } AVCodecParser ff_mjpeg_parser = { .codec_ids = { AV_CODEC_ID_MJPEG }, .priv_data_size = sizeof(MJPEGParserContext), .parser_parse = jpeg_parse, .parser_close = ff_parse_close, };