Merge branch 'hsi-reduction'

* hsi-reduction:
  Add mp3 quality comparision for different mp3 quality levels.
  Reduce host signal interference by using prev/next value during decode.
	This improves robustness by significantly decreasing convolutional code error.
Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/gen-mp3q-clip.sh

+#!/bin/bash
+
+SEEDS=$(seq 5)
+STRENGTHS="10 15"
+MP3_QUALITIES="128 64 48"
+MULTI_CLIP=4
+
+if [ "x$1" == "xmk" ]; then
+  echo -n "all:"
+
+  for STRENGTH in $STRENGTHS
+  do
+    FILE="snr-$STRENGTH"
+    echo -n " $FILE"
+  done
+
+  for SEED in $SEEDS
+  do
+    for STRENGTH in $STRENGTHS
+    do
+      for Q in $MP3_QUALITIES
+      do
+        FILE="mp3-$Q-$STRENGTH-$SEED"
+        echo -n " $FILE"
+      done
+    done
+  done
+
+  echo
+  echo
+
+  for STRENGTH in $STRENGTHS
+  do
+    FILE="snr-$STRENGTH"
+    echo "$FILE:"
+    echo -e "\t( cd ..; AWM_SET=huge2 AWM_PARAMS='--strength $STRENGTH' snr.sh ) >x$FILE"
+    echo -e "\tmv x$FILE $FILE"
+    echo
+  done
+
+  for SEED in $SEEDS
+  do
+    for STRENGTH in $STRENGTHS
+    do
+      for Q in $MP3_QUALITIES
+      do
+        FILE="mp3-$Q-$STRENGTH-$SEED"
+        echo "$FILE:"
+        echo -e "\t( cd ..; AWM_RAND_PATTERN=1 AWM_SET=huge2 AWM_CLIP='50' AWM_PARAMS_ADD='--strength $STRENGTH' AWM_MULTI_CLIP='$MULTI_CLIP' AWM_SEEDS=$SEED AWM_FILE='t-$FILE' ber-test.sh mp3 $Q ) >x$FILE"
+        echo -e "\tmv x$FILE $FILE"
+        echo
+      done
+    done
+  done
+fi
+
+if [ "x$1" == "xadoc" ]; then
+  echo '[frame="topbot",options="header",cols="<1,4*<"]'
+  echo '|=========================='
+  echo '| *Strength* | *SNR* | *mp3 128kbit/s* | *mp3 64kbit/s* | *mp3 48kbit/s*'
+
+  for STRENGTH in $STRENGTHS
+  do
+    echo -n "| *$STRENGTH* "
+    cat snr-$STRENGTH | awk '{printf ("| %.2f ", $1);}'
+    for Q in $MP3_QUALITIES
+    do
+      for FILE in "mp3-$Q-$STRENGTH-*"
+      do
+        cat $FILE
+      done | grep -v '#' | awk '{bad += $1; n += $2} END {if (n==0) n=1;fer=100.0*bad/n; bold=fer>0?"*":" ";printf ("| %s%.2f%s", bold, fer, bold)}'
+    done
+    echo
+  done
+
+  echo '|=========================='
+fi

src/wmget.cc

@@ -81,11 +81,17 @@ mix_decode (const Key& key, vector<vector<complex<float>>>& fft_out, int n_chann
               const double min_db = -96;
 
               const size_t index = mix_entries[b].frame * n_channels + ch;
+              const size_t next_index = (index + n_channels) < fft_out.size() ? index + n_channels : index - n_channels;
+              const size_t prev_index = (int (index) - n_channels) >= 0 ? index - n_channels : index + n_channels;
+
               const int u = mix_entries[b].up;
               const int d = mix_entries[b].down;
 
               umag += db_from_complex (fft_out[index][u], min_db);
+              umag -= (db_from_complex (fft_out[prev_index][u], min_db) + db_from_complex (fft_out[next_index][u], min_db)) * 0.5;
+
               dmag += db_from_complex (fft_out[index][d], min_db);
+              dmag -= (db_from_complex (fft_out[prev_index][d], min_db) + db_from_complex (fft_out[next_index][d], min_db)) * 0.5;
             }
         }
       if ((f % Params::frames_per_bit) == (Params::frames_per_bit - 1))
@@ -113,16 +119,24 @@ linear_decode (const Key& key, vector<vector<complex<float>>>& fft_out, int n_ch
       for (int ch = 0; ch < n_channels; ch++)
         {
           const size_t index = bit_pos_gen.data_frame (f) * n_channels + ch;
+          const size_t next_index = (index + n_channels) < fft_out.size() ? index + n_channels : index - n_channels;
+          const size_t prev_index = (int (index) - n_channels) >= 0 ? index - n_channels : index + n_channels;
+
           UpDownArray up, down;
           up_down_gen.get (f, up, down);
 
           const double min_db = -96;
           for (auto u : up)
-            umag += db_from_complex (fft_out[index][u], min_db);
+            {
+              umag += db_from_complex (fft_out[index][u], min_db);
+              umag -= 0.5 * (db_from_complex (fft_out[prev_index][u], min_db) + db_from_complex (fft_out[next_index][u], min_db));
+            }
 
           for (auto d : down)
-            dmag += db_from_complex (fft_out[index][d], min_db);
-
+            {
+              dmag += db_from_complex (fft_out[index][d], min_db);
+              dmag -= 0.5 * (db_from_complex (fft_out[prev_index][d], min_db) + db_from_complex (fft_out[next_index][d], min_db));
+            }
         }
       if ((f % Params::frames_per_bit) == (Params::frames_per_bit - 1))
         {