static int xan_decode_init(AVCodecContext *avctx)

{

    XanContext *s = avctx->priv_data;

    int i;



    s->avctx = avctx;



    if ((avctx->codec->id == CODEC_ID_XAN_WC3) && 

        (s->avctx->palctrl == NULL)) {

        av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");

        return -1;

    }



    avctx->pix_fmt = PIX_FMT_PAL8;

    avctx->has_b_frames = 0;

    dsputil_init(&s->dsp, avctx);



    

    for (i = 0; i < 256; i++) {

        y_r_table[i] = Y_R * i;

        y_g_table[i] = Y_G * i;

        y_b_table[i] = Y_B * i;



        u_r_table[i] = U_R * i;

        u_g_table[i] = U_G * i;

        u_b_table[i] = U_B * i;



        v_r_table[i] = V_R * i;

        v_g_table[i] = V_G * i;

        v_b_table[i] = V_B * i;

    }



    if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))

        return -1;

    

    s->buffer1 = av_malloc(avctx->width * avctx->height);

    s->buffer2 = av_malloc(avctx->width * avctx->height);

    if (!s->buffer1 || !s->buffer2)

        return -1;



    return 0;

}
