Function vaQueryImageFormats 

pub unsafe extern "C" fn vaQueryImageFormats(
    dpy: VADisplay,
    format_list: *mut VAImageFormat,
    num_formats: *mut c_int,
) -> VAStatus

Query supported image formats The caller must provide a “format_list” array that can hold at least vaMaxNumImageFormats() entries. The actual number of formats returned in “format_list” is returned in “num_formats”.