~ubuntu-branches/debian/experimental/libav/experimental

/*

 * MJPEG parser

 * Copyright (c) 2000, 2001 Fabrice Bellard

 * Copyright (c) 2003 Alex Beregszaszi

 * Copyright (c) 2003-2004 Michael Niedermayer

 *

 * This file is part of Libav.

 *

 * Libav 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.

 *

 * Libav 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 Libav; 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"

/**

 * 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(ParseContext *pc, const uint8_t *buf, int buf_size){

    int vop_found, i;

    uint16_t state;

    vop_found= pc->frame_start_found;

    state= pc->state;

    i=0;

    if(!vop_found){

        for(i=0; i<buf_size; i++){

            state= (state<<8) | buf[i];

            if(state == 0xFFD8){

                i++;

                vop_found=1;

                break;

            }

        }

    }

    if(vop_found){

        /* EOF considered as end of frame */

        if (buf_size == 0)

            return 0;

        for(; i<buf_size; i++){

            state= (state<<8) | buf[i];

            if(state == 0xFFD8){

                pc->frame_start_found=0;

                pc->state=0;

                return i-1;

            }

        }

    }

    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)

{

    ParseContext *pc = s->priv_data;

    int next;

    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){

        next= buf_size;

    }else{

        next= find_frame_end(pc, 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(ParseContext),

    .parser_parse   = jpeg_parse,

    .parser_close   = ff_parse_close,

};