dcadec: fix xxch_dmix_coeff and xxch_dmix_sf after merge

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dcadec.c

@@ -478,6 +478,8 @@ typedef struct {
     FmtConvertContext fmt_conv;
 } DCAContext;
 
+static float dca_dmix_code(unsigned code);
+
 static const uint16_t dca_vlc_offs[] = {
         0,   512,   640,   768,  1282,  1794,  2436,  3080,  3770,  4454,  5364,
      5372,  5380,  5388,  5392,  5396,  5412,  5420,  5428,  5460,  5492,  5508,
@@ -568,7 +570,7 @@ static int dca_parse_audio_coding_header(DCAContext *s, int base_channel,
     static const int bitlen[11] = { 0, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3 };
     static const int thr[11]    = { 0, 1, 3, 3, 3, 3, 7, 7, 7, 7, 7 };
     int hdr_pos = 0, hdr_size = 0;
-    float sign, mag, scale_factor;
+    float scale_factor;
     int this_chans, acc_mask;
     int embedded_downmix;
     int nchans, mask[8];
@@ -598,8 +600,8 @@ static int dca_parse_audio_coding_header(DCAContext *s, int base_channel,
         /* check for downmixing information */
         if (get_bits1(&s->gb)) {
             embedded_downmix = get_bits1(&s->gb);
-            scale_factor     =
-               1.0f / dca_dmixtable[(get_bits(&s->gb, 6) - 1) << 2];
+            coeff            = get_bits(&s->gb, 6);
+            scale_factor     = -1.0f / dca_dmix_code(FFMAX(coeff<<2, 4)-3);
 
             s->xxch_dmix_sf[s->xxch_chset] = scale_factor;
 
@@ -619,10 +621,8 @@ static int dca_parse_audio_coding_header(DCAContext *s, int base_channel,
                         }
 
                         coeff = get_bits(&s->gb, 7);
-                        sign  = (coeff & 64) ? 1.0 : -1.0;
-                        mag   = dca_dmixtable[((coeff & 63) - 1) << 2];
                         ichan = dca_xxch2index(s, 1 << i);
-                        s->xxch_dmix_coeff[j][ichan] = sign * mag;
+                        s->xxch_dmix_coeff[j][ichan] = dca_dmix_code(FFMAX(coeff<<2, 3)-3);
                     }
                 }
             }