fix issue with unclipped dither

src/codecs/sample.cpp

@@ -17,12 +17,9 @@ static uint64_t sSeed1{0};
 static uint64_t sSeed2{0};
 
 auto shiftWithDither(int64_t src, uint_fast8_t bits) -> Sample {
-  // Generate `bits` random bits
-  uint64_t mask = 0xFFFFFFFF;
-  mask >>= 32 - bits;
-  int64_t noise = static_cast<int32_t>(komirand(&sSeed1, &sSeed2) & mask);
-  // Apply to the sample, then shift to 16 bit.
-  return (src + noise) >> bits;
+  // FIXME: Use a better dither.
+  int16_t noise = static_cast<int16_t>(komirand(&sSeed1, &sSeed2) & 1);
+  return (src >> bits) ^ noise;
 }
 
 }  // namespace sample