Better handling of DTX for range coder state checks

src/opus_decoder.c

@@ -442,7 +442,10 @@ static int opus_decode_frame(OpusDecoder *st, const unsigned char *data,
     	            st->channels, window, st->Fs);
     }
 
-    st->rangeFinal = dec.rng ^ redundant_rng;
+    if (len <= 1)
+       st->rangeFinal = 0;
+    else
+       st->rangeFinal = dec.rng ^ redundant_rng;
 
     st->prev_mode = mode;
     st->prev_redundancy = redundancy;

src/opus_encoder.c

@@ -261,6 +261,7 @@ int opus_encode_float(OpusEncoder *st, const opus_val16 *pcm, int frame_size,
     opus_uint32 redundant_rng = 0;
     ALLOC_STACK;
 
+    st->rangeFinal = 0;
     if (400*frame_size != st->Fs && 200*frame_size != st->Fs && 100*frame_size != st->Fs &&
          50*frame_size != st->Fs &&  25*frame_size != st->Fs &&  50*frame_size != 3*st->Fs)
         return OPUS_BAD_ARG;