only decodes when demod in sync and SNR above a threshold, works OK with no channel...

git-svn-id: https://svn.code.sf.net/p/freetel/code@591 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/codec2-dev/fltk/fl_fdmdv.cxx b/codec2-dev/fltk/fl_fdmdv.cxx
index 9d1353d82a40c61ad05fd9034bab443010aacd22..d5894917b89a017b6f800a772c1939f9bec0b204 100644 (file)
--- a/codec2-dev/fltk/fl_fdmdv.cxx
+++ b/codec2-dev/fltk/fl_fdmdv.cxx
@@ -696,25 +696,53 @@ void per_frame_rx_processing(short  output_buf[], /* output buf of decoded speec
        aSNR->add_new_sample(stats.snr_est);
 
        /* 
-          State machine to decode codec bits only if we have a 0,1 sync bit
-          sequence.  Collects two frames of demod bits to decode one frame of
-          codec bits.  
+          State machine to:
+
+          + Mute decoded audio when out of sync.  The demod is synced
+            when we are using the fine freq estimate.
+
+          + Decode codec bits only if we have a 0,1 sync bit
+            sequence.  Collects two frames of demod bits to decode
+            one frame of codec bits.
        */
 
        next_state = *state;
        switch (*state) {
        case 0:
-           if (sync_bit == 0) {
+           /* mute output audio when out of sync */
+
+           if (*n_output_buf < 2*codec2_samples_per_frame(c2) - N8) {
+               for(i=0; i<N8; i++)
+                   output_buf[*n_output_buf + i] = 0;
+               *n_output_buf += N8;
+           }
+           assert(*n_output_buf <= (2*codec2_samples_per_frame(c2)));  
+
+           if ((stats.fest_coarse_fine == 1) && (stats.snr_est > 3.0))
                next_state = 1;
 
+           break;
+       case 1:
+           if (sync_bit == 0) {
+               next_state = 2;
+
                /* first half of frame of codec bits */
 
                memcpy(codec_bits, rx_bits, FDMDV_BITS_PER_FRAME*sizeof(int));
            }
            else
+               next_state = 1;
+           
+           if (stats.fest_coarse_fine == 0)
                next_state = 0;
+
            break;
-       case 1:
+       case 2:
+           next_state = 1;
+
+           if (stats.fest_coarse_fine == 0)
+               next_state = 0;
+
            if (sync_bit == 1) {
                /* second half of frame of codec bits */
 
@@ -743,7 +771,6 @@ void per_frame_rx_processing(short  output_buf[], /* output buf of decoded speec
                assert(*n_output_buf <= (2*codec2_samples_per_frame(c2)));  
                
            }
-           next_state = 0;
            break;
        }       
        *state = next_state;
@@ -872,10 +899,18 @@ static int callback( const void *inputBuffer, void *outputBuffer,
                            input_buf, &n_input_buf, 
                            &nin, &state, codec2);
 
+    /* if demod out of sync copy input audio from A/D to aid in tuning */
+
     if (n_output_buf >= N8) {
-       for(i=0; i<N8; i++)
-           in8k[MEM8+i] = output_buf[i];
-       n_output_buf -= N8;
+       if (state == 0) {
+          for(i=0; i<N8; i++)
+              in8k[MEM8+i] = out8k[i];       /* A/D signal */
+       }
+       else {
+          for(i=0; i<N8; i++)
+              in8k[MEM8+i] = output_buf[i];  /* decoded spech */
+       }
+       n_output_buf -= N8;
     }
     assert(n_output_buf >= 0);