 last call
and the conversion ratio of the current call.
<p/>

<P>
If the user want to bypass this smooth transition and achieve a step response in
the conversion ratio, the <B>src_set_ratio</B> function can be used to set the
starting conversion ratio of the next call to <B>src_process</B> or
<B>src_callback_process</B>.
<p/>

<P>
This function returns non-zero on error and the error return value can be
decoded into a text string using the function documented 
<A HREF="api_misc.html#ErrorReporting">here</A