Index: apps/codecs/libwmapro/wmaprodec.c
===================================================================
--- apps/codecs/libwmapro/wmaprodec.c	(revision 27643)
+++ apps/codecs/libwmapro/wmaprodec.c	(working copy)
@@ -873,11 +873,18 @@
             vals[3] = symbol_to_vec4[idx] & 0xF;
         }
 
+        /* Rockbox: To be able to use rockbox' optimized mdct we need to 
+         * pre-shift the values by >>(nbits-3). */
+        const int nbits = av_log2(s->subframe_len)+1;
+        const int shift = WMAPRO_FRACT-(nbits-3);
+        
         /** decode sign */
         for (i = 0; i < 4; i++) {
             if (vals[i]) {
                 int sign = get_bits1(&s->gb) - 1;
-                ci->coeffs[cur_coeff] = (sign == -1)? -vals[i]<<WMAPRO_FRACT : vals[i]<<WMAPRO_FRACT;
+                /* Rockbox: To be able to use rockbox' optimized mdct we need
+                 * invert the sign. */
+                ci->coeffs[cur_coeff] = (sign == -1)? vals[i]<<shift : -vals[i]<<shift;
                 num_zeros = 0;
             } else {
                 ci->coeffs[cur_coeff] = 0;
@@ -1261,6 +1268,7 @@
             get_bits_count(&s->gb) - s->subframe_offset);
 
     if (transmit_coeffs) {
+        int nbits = av_log2(subframe_len)+1;
         /** reconstruct the per channel data */
         inverse_channel_transform(s);
         for (i = 0; i < s->channels_for_cur_subframe; i++) {
@@ -1271,7 +1279,7 @@
             if (c == s->lfe_channel)
                 memset(&s->tmp[cur_subwoofer_cutoff], 0, sizeof(*s->tmp) *
                        (subframe_len - cur_subwoofer_cutoff));
-                       
+
             /** inverse quantization and rescaling */
             for (b = 0; b < s->num_bands; b++) {
                 const int end = FFMIN(s->cur_sfb_offsets[b+1], s->subframe_len);
@@ -1294,8 +1302,7 @@
             }
 
             /** apply imdct (ff_imdct_half == DCTIV with reverse) */
-            imdct_half(av_log2(subframe_len)+1,
-                          s->channel[c].coeffs, s->tmp);
+            ff_imdct_half(nbits,s->channel[c].coeffs, s->tmp);
                           
         }
     }
Index: apps/codecs/libwmapro/wma.c
===================================================================
--- apps/codecs/libwmapro/wma.c	(revision 27643)
+++ apps/codecs/libwmapro/wma.c	(working copy)
@@ -20,6 +20,7 @@
  */
 
 #include "wma.h"
+#include "codeclib.h" /* needed for av_log2() */
 
 /**
  *@brief Get the samples per frame for this stream.
@@ -109,14 +110,20 @@
 {
     int32_t code, level, sign;
     const unsigned int coef_mask = block_len - 1;
+    /* Rockbox: To be able to use rockbox' optimized mdct we need to pre-shift
+     * the values by >>(nbits-3). */
+    const int nbits = av_log2(block_len)+1;
+    const int shift = WMAPRO_FRACT-(nbits-3);
     for (; offset < num_coefs; offset++) {
         code = get_vlc2(gb, vlc->table, VLCBITS, VLCMAX);
         if (code > 1) {
             /** normal code */
             offset += run_table[code];
             sign = !get_bits1(gb);
-            ptr[offset & coef_mask] = sign ? -level_table[code] : level_table[code];
-            ptr[offset & coef_mask] <<= WMAPRO_FRACT;
+            /* Rockbox: To be able to use rockbox' optimized mdct we need
+             * invert the sign. */
+            ptr[offset & coef_mask] = sign ? level_table[code] : -level_table[code];
+            ptr[offset & coef_mask] <<= shift;
         } else if (code == 1) {
             /** EOB */
             break;
@@ -143,8 +150,8 @@
                 }
             }
             sign = !get_bits1(gb);
-            ptr[offset & coef_mask] = sign ? -level : level;
-            ptr[offset & coef_mask] <<= WMAPRO_FRACT;
+            ptr[offset & coef_mask] = sign ? level : -level;
+            ptr[offset & coef_mask] <<= shift;
         }
     }
     /** NOTE: EOB can be omitted */