diff --git a/libavcodec/vmixdec.c b/libavcodec/vmixdec.c
index 61f97c1bb4..962ab8339b 100644
--- a/libavcodec/vmixdec.c
+++ b/libavcodec/vmixdec.c
@@ -55,22 +55,17 @@ typedef struct VMIXContext {
     IDCTDSPContext idsp;
 } VMIXContext;
 
-static const uint8_t quality[256] = {
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1, 64, 56, 52, 48, 44,
-    12, 36, 32, 28, 24, 22, 20, 18, 16, 14, 12, 10,  8,  7,  6,  5,
-     4,  3,  2,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
-     1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
+static const uint8_t quality[] = {
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 1,64,63,62,61,
+   60,59,58,57,56,55,54,53,52,51,
+   50,49,48,47,46,45,44,43,42,41,
+   40,39,38,37,36,35,34,33,32,31,
+   30,29,28,27,26,25,24,23,22,21,
+   20,19,18,17,16,15,14,13,12,11,
+   10, 9, 8, 7, 6, 5, 4, 3, 2, 1,
 };
 
 static const uint8_t quant[64] = {
@@ -240,7 +235,7 @@ static int decode_frame(AVCodecContext *avctx,
     else if (offset != 3)
         return AVERROR_INVALIDDATA;
 
-    q = quality[avpkt->data[offset - 2]];
+    q = quality[FFMIN(avpkt->data[offset - 2], FF_ARRAY_ELEMS(quality)-1)];
     for (int n = 0; n < 64; n++)
         s->factors[n] = quant[n] * q;