COLOR_FUNC 1996 libavfilter/vf_waveform.c COLOR_FUNC(column, 1, 0) COLOR_FUNC 1997 libavfilter/vf_waveform.c COLOR_FUNC(row_mirror, 0, 1) COLOR_FUNC 1998 libavfilter/vf_waveform.c COLOR_FUNC(row, 0, 0)