optimized waveform generation

2019-04-07 11:31:37 +10:00
parent 62cdd49080
commit a2d7025776
8 changed files with 120 additions and 82 deletions
@@ -0,0 +1,70 @@
+#include "waveform.h"
+
+#include <QtMath>
+
+#include "global/config.h"
+
+int ConvertSampleToHeight(qint8 signed_sample, int channel_height) {
+  int half_channel_height = channel_height >> 1;
+  return (half_channel_height) + qRound(((double(signed_sample) / 128.0)) * half_channel_height);
+}
+
+void olive::ui::DrawWaveform(Clip* clip,
+                              const FootageStream* ms,
+                              long media_length,
+                              QPainter *p,
+                              const QRect& clip_rect,
+                              int waveform_start,
+                              int waveform_limit,
+                              double zoom) {
+
+  int divider = ms->audio_channels;
+
+  int channel_height = clip_rect.height()/ms->audio_channels;
+
+  int last_waveform_index = -1;
+
+  for (int i=waveform_start;i<waveform_limit;i++) {
+    int waveform_index = qFloor((((clip->clip_in() + (double(i)/zoom))/media_length) * ms->audio_preview.size())/divider)*divider;
+
+    if (clip->reversed()) {
+      waveform_index = ms->audio_preview.size() - waveform_index - (ms->audio_channels * 2);
+    }
+
+    if (last_waveform_index < 0) last_waveform_index = waveform_index;
+
+    for (int j=0;j<ms->audio_channels;j++) {
+      int bottom = clip_rect.top()+channel_height*(j+1);
+
+      int offset_range_start = last_waveform_index+(j*2);
+      int offset_range_end = waveform_index+(j*2);
+      int offset_range_min = qMin(offset_range_start, offset_range_end);
+      int offset_range_max = qMax(offset_range_start, offset_range_end);
+
+      // Break if we're about to draw from an index that doesn't exist
+      if (offset_range_min+1 >= ms->audio_preview.size()) {
+        break;
+      }
+
+      int min = ConvertSampleToHeight(ms->audio_preview.at(offset_range_min), channel_height);
+      int max = ConvertSampleToHeight(ms->audio_preview.at(offset_range_min+1), channel_height);
+
+      if ((offset_range_max + 1) < ms->audio_preview.size()) {
+
+        // for waveform drawings, we get the maximum below 0 and maximum above 0 for this waveform range
+        for (int k=offset_range_min+2;k<=offset_range_max;k+=2) {
+          min = ConvertSampleToHeight(ms->audio_preview.at(k), channel_height);
+          max = ConvertSampleToHeight(ms->audio_preview.at(k+1), channel_height);
+        }
+
+        // draw waveforms
+        if (olive::config.rectified_waveforms) {
+          p->drawLine(clip_rect.left()+i, bottom, clip_rect.left()+i, bottom - (max - min));
+        } else {
+          p->drawLine(clip_rect.left()+i, bottom - min, clip_rect.left()+i, bottom - max);
+        }
+      }
+    }
+    last_waveform_index = waveform_index;
+  }
+}