LOWPASS_FUNC      953 libavfilter/vf_waveform.c LOWPASS_FUNC(column,        1, 0)
LOWPASS_FUNC      954 libavfilter/vf_waveform.c LOWPASS_FUNC(row_mirror,    0, 1)
LOWPASS_FUNC      955 libavfilter/vf_waveform.c LOWPASS_FUNC(row,           0, 0)