Function av_expr_parse_and_eval

pub unsafe extern "C" fn av_expr_parse_and_eval(
    res: *mut f64,
    s: *const i8,
    const_names: *const *const i8,
    const_values: *const f64,
    func1_names: *const *const i8,
    funcs1: *const Option<unsafe extern "C" fn(*mut c_void, f64) -> f64>,
    func2_names: *const *const i8,
    funcs2: *const Option<unsafe extern "C" fn(*mut c_void, f64, f64) -> f64>,
    opaque: *mut c_void,
    log_offset: i32,
    log_ctx: *mut c_void,
) -> i32

Parse and evaluate an expression. Note, this is significantly slower than av_expr_eval().

@param res a pointer to a double where is put the result value of the expression, or NAN in case of error @param s expression as a zero terminated string, for example “1+2^3+5*5+sin(2/3)” @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {“PI”, “E”, 0} @param const_values a zero terminated array of values for the identifiers from const_names @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers @param funcs1 NULL terminated array of function pointers for functions which take 1 argument @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments @param opaque a pointer which will be passed to all functions from funcs1 and funcs2 @param log_offset log level offset, can be used to silence error messages @param log_ctx parent logging context @return >= 0 in case of success, a negative value corresponding to an AVERROR code otherwise