Detect out-of-range samples on output and restart with lower gain

main/main.cpp

@@ -121,6 +121,8 @@ int main(int argc, char **argv)
         SoftDetector
     } detector = CompoundDetector;
 
+    bool ignoreClipping = false;
+
     while (1) {
         int optionIndex = 0;
 
@@ -155,6 +157,7 @@ int main(int argc, char **argv)
             { "timemap",       1, 0, 'M' },
             { "freqmap",       1, 0, 'Q' },
             { "pitchmap",      1, 0, 'C' },
+            { "ignore-clipping", 0, 0, 'i' },
             { 0, 0, 0, 0 }
         };
 
@@ -193,6 +196,7 @@ int main(int argc, char **argv)
         case 'M': timeMapFile = optarg; break;
         case 'Q': freqMapFile = optarg; freqOrPitchMapSpecified = true; break;
         case 'C': pitchMapFile = optarg; freqOrPitchMapSpecified = true; break;
+        case 'i': ignoreClipping = true; break;
         default:  help = true; break;
         }
     }
@@ -283,6 +287,8 @@ int main(int argc, char **argv)
         cerr << "         --pitch-hq       In RT mode, use a slower, higher quality pitch shift" << endl;
         cerr << "         --centre-focus   Preserve focus of centre material in stereo" << endl;
         cerr << "                          (at a cost in width and individual channel quality)" << endl;
+        cerr << "         --ignore-clipping Ignore clipping at output; the default is to restart" << endl;
+        cerr << "                           with reduced gain if clipping occurs" << endl;
         cerr << endl;
         cerr << "  -d<N>, --debug <N>      Select debug level (N = 0,1,2,3); default 0, full 3" << endl;
         cerr << "                          (N.B. debug level 3 includes audible ticks in output)" << endl;
@@ -554,14 +560,24 @@ int main(int argc, char **argv)
     
     RubberBandStretcher::setDefaultDebugLevel(debug);
 
+    size_t countIn = 0, countOut = 0;
+
+    float gain = 1.f;
+    bool successful = false;
+
+    while (!successful) { // we may have to repeat with a modified
+                          // gain, if clipping occurs
+        successful = true;
+
         RubberBandStretcher ts(sfinfo.samplerate, channels, options,
                                ratio, frequencyshift);
-
         ts.setExpectedInputDuration(sfinfo.frames);
 
         float *fbuf = new float[channels * ibs];
         float **ibuf = new float *[channels];
-    for (size_t i = 0; i < channels; ++i) ibuf[i] = new float[ibs];
+        for (size_t i = 0; i < channels; ++i) {
+            ibuf[i] = new float[ibs];
+        }
 
         int frame = 0;
         int percent = 0;
@@ -618,7 +634,9 @@ int main(int argc, char **argv)
 
         std::map<size_t, double>::const_iterator freqMapItr = freqMap.begin();
     
-    size_t countIn = 0, countOut = 0;
+        countIn = 0;
+        countOut = 0;
+        bool clipping = false;
         
         while (frame < sfinfo.frames) {
 
@@ -645,7 +663,9 @@ int main(int argc, char **argv)
                 }
             }
         
-	if ((count = sf_readf_float(sndfile, fbuf, thisBlockSize)) < 0) break;
+            if ((count = sf_readf_float(sndfile, fbuf, thisBlockSize)) < 0) {
+                break;
+            }
         
             countIn += count;
 
@@ -677,19 +697,19 @@ int main(int argc, char **argv)
                 float *fobf = new float[channels * avail];
                 for (size_t c = 0; c < channels; ++c) {
                     for (int i = 0; i < avail; ++i) {
-                    float value = obf[c][i];
+                        float value = gain * obf[c][i];
+                        if (ignoreClipping) { // i.e. just clamp, don't bail out
                             if (value > 1.f) value = 1.f;
                             if (value < -1.f) value = -1.f;
+                        } else {
+                            if (value >= 1.f || value < -1.f) {
+                                clipping = true;
+                                gain = (0.999f / fabsf(obf[c][i]));
+                            }
+                        }
                         fobf[i * channels + c] = value;
                     }
                 }
-//            cout << "fobf mean: ";
-//    double d = 0;
-//    for (int i = 0; i < avail; ++i) {
-//        d += fobf[i];
-//    }
-//    d /= avail;
-//    cout << d << endl;
                 sf_writef_float(sndfileOut, fobf, avail);
                 delete[] fobf;
                 for (size_t i = 0; i < channels; ++i) {
@@ -698,6 +718,17 @@ int main(int argc, char **argv)
                 delete[] obf;
             }
 
+            if (clipping) {
+                if (!quiet) {
+                    cerr << "NOTE: Clipping detected at output sample "
+                         << countOut << ", restarting with "
+                         << "reduced gain of " << gain
+                         << " (supply --ignore-clipping to avoid this)" << endl;
+                }
+                successful = false;
+                break;
+            }
+            
             if (frame == 0 && !realtime && !quiet) {
                 cerr << "Pass 2: Processing..." << endl;
             }
@@ -713,6 +744,12 @@ int main(int argc, char **argv)
             frame += thisBlockSize;
         }
 
+        if (!successful) {
+            sf_seek(sndfile, 0, SEEK_SET);
+            sf_seek(sndfileOut, 0, SEEK_SET);
+            continue;
+        }
+    
         if (!quiet) {
             cerr << "\r    " << endl;
         }
@@ -734,7 +771,7 @@ int main(int argc, char **argv)
                 float *fobf = new float[channels * avail];
                 for (size_t c = 0; c < channels; ++c) {
                     for (int i = 0; i < avail; ++i) {
-                    float value = obf[c][i];
+                        float value = gain * obf[c][i];
                         if (value > 1.f) value = 1.f;
                         if (value < -1.f) value = -1.f;
                         fobf[i * channels + c] = value;
@@ -751,6 +788,7 @@ int main(int argc, char **argv)
                 usleep(10000);
             }
         }
+    }
     
     sf_close(sndfile);
     sf_close(sndfileOut);