static AVFrame *get_video_buffer(AVFilterLink *inlink, int w, int h)

{

    PadContext *s = inlink->dst->priv;



    AVFrame *frame = ff_get_video_buffer(inlink->dst->outputs[0],

                                         w + (s->w - s->in_w),

                                         h + (s->h - s->in_h));

    int plane;



    if (!frame)

        return NULL;



    frame->width  = w;

    frame->height = h;



    for (plane = 0; plane < 4 && frame->data[plane]; plane++) {

        int hsub = s->draw.hsub[plane];

        int vsub = s->draw.vsub[plane];

        frame->data[plane] += (s->x >> hsub) * s->draw.pixelstep[plane] +

                              (s->y >> vsub) * frame->linesize[plane];

    }



    return frame;

}
