static void mpegvideo_extract_headers(AVCodecParserContext *s,

                                      AVCodecContext *avctx,

                                      const uint8_t *buf, int buf_size)

{

    ParseContext1 *pc = s->priv_data;

    const uint8_t *buf_end;

    const uint8_t *buf_start= buf;

    uint32_t start_code;

    int frame_rate_index, ext_type, bytes_left;

    int frame_rate_ext_n, frame_rate_ext_d;

    int picture_structure, top_field_first, repeat_first_field, progressive_frame;

    int horiz_size_ext, vert_size_ext, bit_rate_ext;

//FIXME replace the crap with get_bits()

    s->repeat_pict = 0;

    buf_end = buf + buf_size;

    while (buf < buf_end) {

        start_code= -1;

        buf= ff_find_start_code(buf, buf_end, &start_code);

        bytes_left = buf_end - buf;

        switch(start_code) {

        case PICTURE_START_CODE:

            ff_fetch_timestamp(s, buf-buf_start-4, 1);



            if (bytes_left >= 2) {

                s->pict_type = (buf[1] >> 3) & 7;

            }

            break;

        case SEQ_START_CODE:

            if (bytes_left >= 7) {

                pc->width  = (buf[0] << 4) | (buf[1] >> 4);

                pc->height = ((buf[1] & 0x0f) << 8) | buf[2];

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

                frame_rate_index = buf[3] & 0xf;

                pc->frame_rate.den = avctx->time_base.den = ff_frame_rate_tab[frame_rate_index].num;

                pc->frame_rate.num = avctx->time_base.num = ff_frame_rate_tab[frame_rate_index].den;

                avctx->bit_rate = ((buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6))*400;

                avctx->codec_id = CODEC_ID_MPEG1VIDEO;

                avctx->sub_id = 1;

            }

            break;

        case EXT_START_CODE:

            if (bytes_left >= 1) {

                ext_type = (buf[0] >> 4);

                switch(ext_type) {

                case 0x1: /* sequence extension */

                    if (bytes_left >= 6) {

                        horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7);

                        vert_size_ext = (buf[2] >> 5) & 3;

                        bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1);

                        frame_rate_ext_n = (buf[5] >> 5) & 3;

                        frame_rate_ext_d = (buf[5] & 0x1f);

                        pc->progressive_sequence = buf[1] & (1 << 3);

                        avctx->has_b_frames= !(buf[5] >> 7);



                        pc->width  |=(horiz_size_ext << 12);

                        pc->height |=( vert_size_ext << 12);

                        avctx->bit_rate += (bit_rate_ext << 18) * 400;

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

                        avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2;

                        avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1);

                        avctx->codec_id = CODEC_ID_MPEG2VIDEO;

                        avctx->sub_id = 2; /* forces MPEG2 */

                    }

                    break;

                case 0x8: /* picture coding extension */

                    if (bytes_left >= 5) {

                        picture_structure = buf[2]&3;

                        top_field_first = buf[3] & (1 << 7);

                        repeat_first_field = buf[3] & (1 << 1);

                        progressive_frame = buf[4] & (1 << 7);



                        /* check if we must repeat the frame */

                        s->repeat_pict = 1;

                        if (repeat_first_field) {

                            if (pc->progressive_sequence) {

                                if (top_field_first)

                                    s->repeat_pict = 5;

                                else

                                    s->repeat_pict = 3;

                            } else if (progressive_frame) {

                                s->repeat_pict = 2;

                            }

                        }

                    }

                    break;

                }

            }

            break;

        case -1:

            goto the_end;

        default:

            /* we stop parsing when we encounter a slice. It ensures

               that this function takes a negligible amount of time */

            if (start_code >= SLICE_MIN_START_CODE &&

                start_code <= SLICE_MAX_START_CODE)

                goto the_end;

            break;

        }

    }

 the_end: ;

}
