Make Analog Auto Gain Control Mostly Tolerable;

include/dsd.h

@@ -544,6 +544,7 @@ typedef struct
   char slot0light[8];
   float aout_gain;
   float aout_gainR;
+  float aout_gainA;
   float aout_max_buf[200];
   float aout_max_bufR[200];
   float *aout_max_buf_p;

src/dsd_audio2.c

@@ -1352,58 +1352,47 @@ void agf (dsd_opts * opts, dsd_state * state, float samp[160], int slot)
 //automatic gain short mono for analog audio and some digital mono (WIP)
 void agsm (dsd_opts * opts, dsd_state * state, short * input, int len)
 {
-  int i, j;
+  int i;
 
-  UNUSED(state);
+  UNUSED(opts);
+
+  //NOTE: This seems to be doing better now that I got it worked out properly
+  //This may produce a mild buzz sound though on the low end
 
   float avg = 0.0f;        //average of 20 samples
   float coeff = 0.0f;     //gain coeffiecient
   float max = 0.0f;      //the highest sample value
-  float nom = 1500.0f;  //nominator value
-  float gain = (25.0f / opts->audio_gain); UNUSED(gain);
+  float nom = 4800.0f;  //nominator value for 48k
   float samp[960]; memset (samp, 0.0f, 960*sizeof(float));
 
   //assign internal float from short input
   for (i = 0; i < len; i++)
     samp[i] = (float)input[i];
 
-  // gain = 2.5f;
-  // for (i = 0; i < len; i++)
-  //   samp[i] *= gain;
-
-  for (j = 0; j < len/20; j++)
+  for (i = 0; i < len; i++)
   {
-
-    for (i = 0; i < 20; i++)
+    if ( fabsf (samp[i]) > max)
     {
-      if ( fabsf (samp[(j*20)+i]) > max)
-      {
-        max = fabsf (samp[(j*20)+i]);
-      }
+      max = fabsf (samp[i]);
     }
+  }
 
-    for (i = 0; i < 20; i++)
-      avg += (float)samp[(j*20)+i];
+  for (i = 0; i < len; i++)
+    avg += (float)samp[i];
 
-    avg /= 20;
+  avg /= (float)len;
+  
+  coeff = fabsf (nom / max);
+
+  //keep coefficient with tolerable range when silence to prevent crackle/buzz
+  if (coeff > 3.0f) coeff = 3.0f;
+
+  //apply the coefficient to bring the max value to our desired maximum value
+  for (i = 0; i < 20; i++)
+    samp[i] *= coeff;
     
-    coeff = fabsf (nom / max);
-
-
-    //apply the coefficient to bring the max value to our desired maximum value
-    for (i = 0; i < 20; i++)
-    {
-      if ( fabsf (samp[(j*20)+i]) > 110.0f) //try not to apply to near zero values
-        samp[(j*20)+i] *= coeff;
-    }
-    
-    //debug
-    // fprintf (stderr, "\n M: %f; C: %f; A: %f; ", max, coeff, avg);
-
-    max = 0; //reset
-    avg = 0; //reset
-
-  } //end j loop
+  //debug
+  // fprintf (stderr, "\n M: %f; C: %f; A: %f; ", max, coeff, avg);
 
   // debug
   // for (i = 0; i < len; i++)
@@ -1416,6 +1405,8 @@ void agsm (dsd_opts * opts, dsd_state * state, short * input, int len)
   for (i = 0; i < len; i++)
     input[i] = (short)samp[i];
 
+  state->aout_gainA = coeff; //store for internal use
+
 }
 
 //until analog agc is fixed, going to use a manual gain control on this

src/dsd_main.c

@@ -907,6 +907,7 @@ initState (dsd_state * state)
   sprintf (state->slot2light, "%s", "");
   state->aout_gain = 25.0f;
   state->aout_gainR = 25.0f;
+  state->aout_gainA = 0.0f; //use purely as a display or internal value, no user setting
   memset (state->aout_max_buf, 0, sizeof (float) * 200);
   state->aout_max_buf_p = state->aout_max_buf;
   state->aout_max_buf_idx = 0;

src/dsd_ncurses.c

@@ -2403,7 +2403,9 @@ ncursesPrinter (dsd_opts * opts, dsd_state * state)
 
   if ( opts->audio_out_type == 0 && (opts->frame_provoice == 1 || opts->monitor_input_audio == 1) )
   {
-    printw ("| Pulse Analog Output: %i kHz; %i Ch; G: %02.0f%% (/|*) Manual ", opts->pulse_raw_rate_out/1000, opts->pulse_raw_out_channels, opts->audio_gainA);
+    printw ("| Pulse Analog Output: %i kHz; %i Ch; G: %02.0f%% (/|*) ", opts->pulse_raw_rate_out/1000, opts->pulse_raw_out_channels, opts->audio_gainA);
+    if (opts->audio_gainA == 0.0f) printw ("Auto   ");
+    else printw ("Manual ");
     if (opts->audio_in_type != 3) printw ("RMS: %04ld; ", opts->rtl_rms);
     if (opts->use_lpf == 1) printw ("F: |LP|"); else printw ("F: |  |");
     if (opts->use_hpf == 1) printw ("HP|");     else printw ("  |");