text: /*
   * 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,
  };
  