improve video, ignore same image

libs/scrap/src/common/mod.rs

@@ -30,3 +30,16 @@ pub use self::convert::*;
 pub const STRIDE_ALIGN: usize = 64; // commonly used in libvpx vpx_img_alloc caller
 
 mod vpx;
+
+#[inline]
+pub fn would_block_if_equal(old: &mut Vec<u128>, b: &[u8]) -> std::io::Result<()> {
+    let b = unsafe {
+        std::slice::from_raw_parts::<u128>(b.as_ptr() as _, b.len() / 16)
+    };
+    if b == &old[..] {
+        return Err(std::io::ErrorKind::WouldBlock.into());
+    }
+    old.resize(b.len(), 0);
+    old.copy_from_slice(b);
+    Ok(())
+}