VAR_TEXT_W       1431 libavfilter/vf_drawtext.c     s->var_values[VAR_TW] = s->var_values[VAR_TEXT_W] = max_text_line_w;
VAR_TEXT_W       1541 libavfilter/vf_drawtext.c            (int)s->var_values[VAR_TEXT_W], (int)s->var_values[VAR_TEXT_H],