fixed waveform issue

app/audio/audiovisualwaveform.cpp

@@ -143,6 +143,9 @@ void AudioVisualWaveform::OverwriteSums(const AudioVisualWaveform &sums, const r
 
     // Get our source sample
     int their_start_index = time_to_samples(offset, rate_dbl);
+    if (their_start_index >= their_arr.size()) {
+      continue;
+    }
 
     // Determine how much we're copying
     int copy_len = their_arr.size() - their_start_index;

app/render/previewautocacher.cpp

@@ -203,7 +203,7 @@ void PreviewAutoCacher::AudioRendered()
             foreach (TimeRange r, intersections) {
               // For each range, adjust it relative to the block and write it
               r -= block->in();
-              block->waveform().OverwriteSums(waveform_info.waveform, r.in(), r.in(), r.length());
+              block->waveform().OverwriteSums(waveform_info.waveform, r.in(), r.in() - waveform_info.range.in(), r.length());
             }
 
             emit block->PreviewChanged();