From a99674b911cb9b2fa398ccf61830d5933ccaf931 Mon Sep 17 00:00:00 2001
From: metamuffin <metamuffin@disroot.org>
Date: Wed, 7 Dec 2022 17:47:28 +0100
Subject: extend format to support abitrary transform

---
 evc/spec.md | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/evc/spec.md b/evc/spec.md
index da05da1..a6f0da7 100644
--- a/evc/spec.md
+++ b/evc/spec.md
@@ -14,7 +14,17 @@
       - sub-blocks: _`[block; 2]` (see above)_
     - **Reference-Block** (reuses previous frame in some way)
       - translation: _`i8, i8`_
-      <!-- - factor: _`i8`_ (represents multiplication with $1.1^n$) -->
+    - **Advanced-Reference-Block** (reuses previous frame in some way)
+      - translation: _`s8, s8`_ (translation encoded as _floats_)
+      - transform: _`s8, s8, s8, s8`_ (2x2-matrix of _floats_ applied before
+        sampling)
+      - value_scale: _`s8`_ (represents multiplication of each color component
+        with $1.1^n$)
+
+### _`s8`_
+
+8-bit scalar. When read as _`i8`_ represents a value of $\frac{x}{|x|} *
+\sqrt{2}^{|{x}| - 4}$ for $x \neq 0$, otherwise 0.
 
 ### Todo
 
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