static int amv_encode_picture(AVCodecContext *avctx, AVPacket *pkt,
                              const AVFrame *pic_arg, int *got_packet)

{
    MpegEncContext *s = avctx->priv_data;
    AVFrame *pic;
    int i, ret;
    int chroma_h_shift, chroma_v_shift;

    av_pix_fmt_get_chroma_sub_sample(avctx->pix_fmt, &chroma_h_shift, &chroma_v_shift);

    //CODEC_FLAG_EMU_EDGE have to be cleared
    if(s->avctx->flags & CODEC_FLAG_EMU_EDGE)
        return AVERROR(EINVAL);

    pic = av_frame_clone(pic_arg);
    if (!pic)
        return AVERROR(ENOMEM);
    //picture should be flipped upside-down
    for(i=0; i < 3; i++) {
        int vsample = i ? 2 >> chroma_v_shift : 2;
        pic->data[i] += (pic->linesize[i] * (vsample * (8 * s->mb_height -((s->height/V_MAX)&7)) - 1 ));
        pic->linesize[i] *= -1;
    }
    ret = ff_MPV_encode_picture(avctx, pkt, pic, got_packet);
    av_frame_free(&pic);
    return ret;
}