lavfi/aevalsrc: switch to an AVOptions-based system.

doc/filters.texi

@@ -1496,18 +1496,13 @@ This source accepts in input one or more expressions (one for each
 channel), which are evaluated and used to generate a corresponding
 audio signal.
 
-It accepts the syntax: @var{exprs}[::@var{options}].
-@var{exprs} is a list of expressions separated by ":", one for each
-separate channel. In case the @var{channel_layout} is not
-specified, the selected channel layout depends on the number of
-provided expressions.
-
-@var{options} is an optional sequence of @var{key}=@var{value} pairs,
-separated by ":".
-
-The description of the accepted options follows.
+This source accepts the following options:
 
 @table @option
+@item exprs
+Set the '|'-separated expressions list for each separate channel. In case the
+@option{channel_layout} option is not specified, the selected channel layout
+depends on the number of provided expressions.
 
 @item channel_layout, c
 Set the channel layout. The number of channels in the specified layout
@@ -1558,14 +1553,14 @@ aevalsrc=0
 Generate a sin signal with frequency of 440 Hz, set sample rate to
 8000 Hz:
 @example
-aevalsrc="sin(440*2*PI*t)::s=8000"
+aevalsrc="sin(440*2*PI*t):s=8000"
 @end example
 
 @item
 Generate a two channels signal, specify the channel layout (Front
 Center + Back Center) explicitly:
 @example
-aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
+aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
 @end example
 
 @item
@@ -1583,7 +1578,7 @@ aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
 @item
 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
 @example
-aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
+aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
 @end example
 
 @end itemize