0,0 → 1,134 |
/* |
* 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, |
}; |