The default value of @var{x} and @var{y} is 0.
+If @var{x} or @var{y} evaluate to a negative number, they'll be changed
+so the input image is centered on the padded area.
+
@item color
Specify the color of the padded area. For the syntax of this option,
check the "Color" section in the ffmpeg-utils manual.
Default value is @samp{init}.
+@item aspect
+Pad to aspect instead to a resolution.
+
@end table
The value for the @var{width}, @var{height}, @var{x}, and @var{y}
otherwise event in frequency domain is represented more accurately
(such as bass guitar). Acceptable range is @code{[0.002, 1]}. Default value is @code{0.17}.
+@item attack
+Set attack time in seconds. The default is @code{0} (disabled). Otherwise, it
+limits future samples by applying asymmetric windowing in time domain, useful
+when low latency is required. Accepted range is @code{[0, 1]}.
+
@item basefreq
Specify the transform base frequency. Default value is @code{20.01523126408007475},
which is frequency 50 cents below E0. Acceptable range is @code{[10, 100000]}.