mirror of https://git.ffmpeg.org/ffmpeg.git
137 lines
3.9 KiB
C
137 lines
3.9 KiB
C
/*
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* MJPEG parser
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* Copyright (c) 2000, 2001 Fabrice Bellard
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* Copyright (c) 2003 Alex Beregszaszi
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* Copyright (c) 2003-2004 Michael Niedermayer
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* MJPEG parser.
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*/
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#include "parser.h"
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typedef struct MJPEGParserContext{
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ParseContext pc;
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int size;
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}MJPEGParserContext;
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/**
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* Find the end of the current frame in the bitstream.
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* @return the position of the first byte of the next frame, or -1
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*/
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static int find_frame_end(MJPEGParserContext *m, const uint8_t *buf, int buf_size){
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ParseContext *pc= &m->pc;
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int vop_found, i;
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uint32_t state;
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vop_found= pc->frame_start_found;
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state= pc->state;
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i=0;
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if(!vop_found){
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for(i=0; i<buf_size;){
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state= (state<<8) | buf[i];
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if(state>=0xFFC00000 && state<=0xFFFEFFFF){
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if(state>=0xFFD8FFC0 && state<=0xFFD8FFFF){
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i++;
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vop_found=1;
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break;
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}else if(state<0xFFD00000 || state>0xFFD9FFFF){
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m->size= (state&0xFFFF)-1;
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}
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}
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if(m->size>0){
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int size= FFMIN(buf_size-i, m->size);
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i+=size;
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m->size-=size;
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state=0;
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continue;
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}else
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i++;
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}
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}
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if(vop_found){
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/* EOF considered as end of frame */
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if (buf_size == 0)
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return 0;
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for(; i<buf_size;){
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state= (state<<8) | buf[i];
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if(state>=0xFFC00000 && state<=0xFFFEFFFF){
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if(state>=0xFFD8FFC0 && state<=0xFFD8FFFF){
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pc->frame_start_found=0;
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pc->state=0;
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return i-3;
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} else if(state<0xFFD00000 || state>0xFFD9FFFF){
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m->size= (state&0xFFFF)-1;
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if (m->size >= 0x8000)
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m->size = 0;
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}
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}
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if(m->size>0){
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int size= FFMIN(buf_size-i, m->size);
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i+=size;
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m->size-=size;
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state=0;
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continue;
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}else
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i++;
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}
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}
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pc->frame_start_found= vop_found;
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pc->state= state;
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return END_NOT_FOUND;
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}
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static int jpeg_parse(AVCodecParserContext *s,
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AVCodecContext *avctx,
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const uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *buf, int buf_size)
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{
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MJPEGParserContext *m = s->priv_data;
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ParseContext *pc = &m->pc;
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int next;
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if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
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next= buf_size;
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}else{
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next= find_frame_end(m, buf, buf_size);
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if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
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*poutbuf = NULL;
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*poutbuf_size = 0;
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return buf_size;
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}
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}
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return next;
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}
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AVCodecParser ff_mjpeg_parser = {
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.codec_ids = { AV_CODEC_ID_MJPEG, AV_CODEC_ID_JPEGLS },
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.priv_data_size = sizeof(MJPEGParserContext),
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.parser_parse = jpeg_parse,
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.parser_close = ff_parse_close,
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};
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