shithub: opus

Info  •  Files  •  Log  •  Branches

Handle the sign of the DRED offset

--- a/silk/dred_decoder.c

+++ b/silk/dred_decoder.c

@@ -36,9 +36,13 @@

 #include "dred_coding.h"

 #include "celt/entdec.h"

+/* From http://graphics.stanford.edu/~seander/bithacks.html#FixedSignExtend */

+static int sign_extend(int x, int b) {

+  int m = 1U << (b - 1);

+  return (x ^ m) - m;

+}

-

 int dred_ec_decode(OpusDRED *dec, const opus_uint8 *bytes, int num_bytes, int min_feature_frames)

 {

   const opus_uint16 *p0              = DRED_rdovae_get_p0_pointer();

@@ -57,7 +61,7 @@

   /* decode initial state and initialize RDOVAE decoder */

   ec_dec_init(&ec, (unsigned char*)bytes, num_bytes);

-  dec->dred_offset = ec_dec_uint(&ec, 32);

+  dec->dred_offset = sign_extend(ec_dec_uint(&ec, 32), 5);

   q0 = ec_dec_uint(&ec, 16);

   dQ = ec_dec_uint(&ec, 8);

   /*printf("%d %d %d\n", dred_offset, q0, dQ);*/

-- 

⑨