Function vmeta_frame_v2_write 

pub unsafe extern "C" fn vmeta_frame_v2_write(
    buf: *mut vmeta_buffer,
    meta: *const vmeta_frame_v2,
) -> c_int

Write “Parrot Video Metadata” v2 frame metadata. This function fills the supplied buffer with the serialized metadata. The size of the data written is returned through the pos field in the buf structure. The buf structure must have been previously initialized using the vmeta_buffer_set_data() function with a previously allocated buffer and its size. The pos field in the buf structure does not need to be 0 prior to calling the function (i.e. data can already be present in the buffer). The ownership of the buffer stays with the caller. @param buf: pointer to the buffer structure (output) @param meta: pointer to the frame metadata structure @return 0 on success, negative errno value in case of error