函数 av_probe_input_buffer 

pub unsafe extern "C" fn av_probe_input_buffer(
    pb: *mut AVIOContext,
    fmt: *mut *const AVInputFormat,
    url: *const c_char,
    logctx: *mut c_void,
    offset: c_uint,
    max_probe_size: c_uint,
) -> c_int

Like av_probe_input_buffer2() but returns 0 on success