Saturate additions in getEnvSfbEnergy in SBR encoding

This avoids wraparounds, which can trigger failed asserts with some inputs. This fixes #158. The implementation of saturated addition loses the contents of the lowest bit though, thus this change affects the output - but the change is said to be acceptable.
mstorsjo · Nov 10, 2023 · 8264e37 · 8264e37
1 parent 4de681c
commit 8264e37
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Showing 3 changed files with 6 additions and 6 deletions.
diff --git a/libSBRenc/src/env_est.cpp b/libSBRenc/src/env_est.cpp
@@ -637,8 +637,8 @@ static FIXP_DBL getEnvSfbEnergy(
     for (; l < stop_pos; l++) {
       nrg2 += YBuffer[l >> YBufferSzShift][k] >> sc1;
     }
-    accu1 += (nrg1 >> dynScale1);
-    accu2 += (nrg2 >> dynScale2);
+    accu1 = fAddSaturate(accu1, (nrg1 >> dynScale1));
+    accu2 = fAddSaturate(accu2, (nrg2 >> dynScale2));
   }
   /* This shift factor is always positive. See comment above. */
   nrgSum +=

diff --git a/test/ref-mono.txt b/test/ref-mono.txt
@@ -1,2 +1,2 @@
-encode hash: 516e51016cbba6068f1aa285a8fdd55b00ada6b0
-decode hash: 3b3b3a17cc5ba50ade75b3ef1a37f96017935fe5
+encode hash: 7f00e85a1eda67964e1b4044a5659a62e3952af2
+decode hash: af682b197a94e32fce09643857fa77b364574571
diff --git a/test/ref-stereo.txt b/test/ref-stereo.txt
@@ -1,2 +1,2 @@
-encode hash: 1179940ca3a5c62de45b6823efbdbe42fce11de2
-decode hash: 85f2a154b46cc6cfa2792ff95c67b4200ce4463b
+encode hash: 8411e71bf6b32576d287764cfa577ea0e9b73280
+decode hash: 30ad42bc97b53c03139cca5437b7d9a861de0e92