PeerStreamer

/*

 * MPEG4 Video frame extraction

 * Copyright (c) 2003 Fabrice Bellard

 * Copyright (c) 2003 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

 */

#include "parser.h"

#include "mpegvideo.h"

#include "mpeg4video.h"

#include "mpeg4video_parser.h"

int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){

    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; i++){

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

            if(state == 0x1B6){

                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&0xFFFFFF00) == 0x100){

                pc->frame_start_found=0;

                pc->state=-1;

                return i-3;

            }

        }

    }

    pc->frame_start_found= vop_found;

    pc->state= state;

    return END_NOT_FOUND;

}

/* XXX: make it use less memory */

static int av_mpeg4_decode_header(AVCodecParserContext *s1,

                                  AVCodecContext *avctx,

                                  const uint8_t *buf, int buf_size)

{

    ParseContext1 *pc = s1->priv_data;

    MpegEncContext *s = pc->enc;

    GetBitContext gb1, *gb = &gb1;

    int ret;

    s->avctx = avctx;

    s->current_picture_ptr = &s->current_picture;

    if (avctx->extradata_size && pc->first_picture){

        init_get_bits(gb, avctx->extradata, avctx->extradata_size*8);

        ret = ff_mpeg4_decode_picture_header(s, gb);

    }

    init_get_bits(gb, buf, 8 * buf_size);

    ret = ff_mpeg4_decode_picture_header(s, gb);

    if (s->width && (!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height)) {

        avcodec_set_dimensions(avctx, s->width, s->height);

    }

    s1->pict_type= s->pict_type;

    pc->first_picture = 0;

    return ret;

}

static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)

{

    ParseContext1 *pc = s->priv_data;

    pc->enc = av_mallocz(sizeof(MpegEncContext));

    if (!pc->enc)

        return -1;

    pc->first_picture = 1;

    return 0;

}

static int mpeg4video_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= ff_mpeg4_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;

        }

    }

    av_mpeg4_decode_header(s, avctx, buf, buf_size);

    *poutbuf = buf;

    *poutbuf_size = buf_size;

    return next;

}

AVCodecParser mpeg4video_parser = {

    { CODEC_ID_MPEG4 },

    sizeof(ParseContext1),

    mpeg4video_parse_init,

    mpeg4video_parse,

    ff_parse1_close,

    ff_mpeg4video_split,

};