Function rsmpeg::ffi::av_expr_count_vars

pub unsafe extern "C" fn av_expr_count_vars(
    e: *mut AVExpr, 
    counter: *mut u32, 
    size: i32
) -> i32

Track the presence of variables and their number of occurrences in a parsed expression

@param counter a zero-initialized array where the count of each variable will be stored @param size size of array @return 0 on success, a negative value indicates that no expression or array was passed or size was zero