PeerStreamer

/*

 * VC-1 and WMV3 parser

 * Copyright (c) 2006-2007 Konstantin Shishkov

 * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, 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

 * VC-1 and WMV3 parser

 */

#include "parser.h"

#include "vc1.h"

#include "get_bits.h"

typedef struct {

    ParseContext pc;

    VC1Context v;

} VC1ParseContext;

static void vc1_extract_headers(AVCodecParserContext *s, AVCodecContext *avctx,

                                const uint8_t *buf, int buf_size)

{

    VC1ParseContext *vpc = s->priv_data;

    GetBitContext gb;

    const uint8_t *start, *end, *next;

    uint8_t *buf2 = av_mallocz(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);

    vpc->v.s.avctx = avctx;

    vpc->v.parse_only = 1;

    next = buf;

    for(start = buf, end = buf + buf_size; next < end; start = next){

        int buf2_size, size;

        next = find_next_marker(start + 4, end);

        size = next - start - 4;

        buf2_size = vc1_unescape_buffer(start + 4, size, buf2);

        init_get_bits(&gb, buf2, buf2_size * 8);

        if(size <= 0) continue;

        switch(AV_RB32(start)){

        case VC1_CODE_SEQHDR:

            vc1_decode_sequence_header(avctx, &vpc->v, &gb);

            break;

        case VC1_CODE_ENTRYPOINT:

            vc1_decode_entry_point(avctx, &vpc->v, &gb);

            break;

        case VC1_CODE_FRAME:

            if(vpc->v.profile < PROFILE_ADVANCED)

                vc1_parse_frame_header    (&vpc->v, &gb);

            else

                vc1_parse_frame_header_adv(&vpc->v, &gb);

            /* keep FF_BI_TYPE internal to VC1 */

            if (vpc->v.s.pict_type == FF_BI_TYPE)

                s->pict_type = FF_B_TYPE;

            else

                s->pict_type = vpc->v.s.pict_type;

            break;

        }

    }

    av_free(buf2);

}

/**

 * finds the end of the current frame in the bitstream.

 * @return the position of the first byte of the next frame, or -1

 */

static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,

                               int buf_size) {

    int pic_found, i;

    uint32_t state;

    pic_found= pc->frame_start_found;

    state= pc->state;

    i=0;

    if(!pic_found){

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

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

            if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){

                i++;

                pic_found=1;

                break;

            }

        }

    }

    if(pic_found){

        /* EOF considered as end of frame */

        if (buf_size == 0)

            return 0;

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

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

            if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){

                pc->frame_start_found=0;

                pc->state=-1;

                return i-3;

            }

        }

    }

    pc->frame_start_found= pic_found;

    pc->state= state;

    return END_NOT_FOUND;

}

static int vc1_parse(AVCodecParserContext *s,

                           AVCodecContext *avctx,

                           const uint8_t **poutbuf, int *poutbuf_size,

                           const uint8_t *buf, int buf_size)

{

    VC1ParseContext *vpc = s->priv_data;

    int next;

    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){

        next= buf_size;

    }else{

        next= vc1_find_frame_end(&vpc->pc, buf, buf_size);

        if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) {

            *poutbuf = NULL;

            *poutbuf_size = 0;

            return buf_size;

        }

    }

    vc1_extract_headers(s, avctx, buf, buf_size);

    *poutbuf = buf;

    *poutbuf_size = buf_size;

    return next;

}

static int vc1_split(AVCodecContext *avctx,

                           const uint8_t *buf, int buf_size)

{

    int i;

    uint32_t state= -1;

    int charged=0;

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

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

        if(IS_MARKER(state)){

            if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){

                charged=1;

            }else if(charged){

                return i-3;

            }

        }

    }

    return 0;

}

AVCodecParser ff_vc1_parser = {

    { CODEC_ID_VC1 },

    sizeof(VC1ParseContext),

    NULL,

    vc1_parse,

    ff_parse1_close,

    vc1_split,

};