Function vmeta_session_perspective_distortion_write 

pub unsafe extern "C" fn vmeta_session_perspective_distortion_write(
    str_: *mut c_char,
    len: usize,
    r1: f32,
    r2: f32,
    r3: f32,
    t1: f32,
    t2: f32,
) -> isize

Write a perspective distortion parameters string. The str string must have been previously allocated. The function writes up to len chars. @param str: pointer to the string to write to (output) @param len: maximum length of the string @param r1: radial distortion parameter R1 @param r2: radial distortion parameter R2 @param r3: radial distortion parameter R3 @param t1: tangential distortion parameter T1 @param t2: tangential distortion parameter T2 @return the length of the string written on success, negative errno value in case of error