implemented foundational reversed block code

Ensured renderers can handle clips that are reversed.

app/dialog/speedduration/speedduration.cpp

@@ -33,6 +33,7 @@ SpeedDurationDialog::SpeedDurationDialog(const rational& timebase, const QList<C
     // show them all as having the same parameters
     bool same_speed = true;
     bool same_duration = true;
+    bool all_reversed = true;
 
     for (int i=1;i<clips.size();i++) {
       ClipBlock* prev_clip = clips_.at(i-1);
@@ -50,8 +51,16 @@ SpeedDurationDialog::SpeedDurationDialog(const rational& timebase, const QList<C
         same_duration = false;
       }
 
+      // Check if all are reversed
+      if (all_reversed
+          && prev_clip->is_reversed() != this_clip->is_reversed()) {
+        all_reversed = false;
+      }
+
       // If we've already determined both are different, no need to continue
-      if (!same_speed && !same_duration) {
+      if (!same_speed
+          && !same_duration
+          && !all_reversed) {
         break;
       }
     }
@@ -97,10 +106,15 @@ SpeedDurationDialog::SpeedDurationDialog(const rational& timebase, const QList<C
     // Pick up when the speed or duration slider changes so we can programmatically link them
     connect(speed_slider_, SIGNAL(ValueChanged(double)), this, SLOT(SpeedChanged()));
     connect(duration_slider_, SIGNAL(ValueChanged(int64_t)), this, SLOT(DurationChanged()));
-  }
 
-  reverse_speed_checkbox_ = new QCheckBox(tr("Reverse Speed"));
-  layout->addWidget(reverse_speed_checkbox_);
+    reverse_speed_checkbox_ = new QCheckBox(tr("Reverse Speed"));
+    if (all_reversed) {
+      reverse_speed_checkbox_->setChecked(clips_.first()->is_reversed());
+    } else {
+      reverse_speed_checkbox_->setTristate();
+    }
+    layout->addWidget(reverse_speed_checkbox_);
+  }
 
   maintain_audio_pitch_checkbox_ = new QCheckBox(tr("Maintain Audio Pitch"));
   layout->addWidget(maintain_audio_pitch_checkbox_);
@@ -216,6 +230,10 @@ void SpeedDurationDialog::accept()
       // Change the speed by calculating the appropriate media out point for this clip
       new BlockSetMediaOutCommand(clip, new_media_out, command);
     }
+
+    if (!reverse_speed_checkbox_->isTristate() && clip->is_reversed() != reverse_speed_checkbox_->isChecked()) {
+      new BlockReverseCommand(clip, command);
+    }
   }
 
   olive::undo_stack.pushIfHasChildren(command);
@@ -311,3 +329,22 @@ void SpeedDurationDialog::DurationChanged()
     }
   }
 }
+
+BlockReverseCommand::BlockReverseCommand(Block *block, QUndoCommand *parent) :
+  QUndoCommand(parent),
+  block_(block)
+{
+}
+
+void BlockReverseCommand::redo()
+{
+  rational temp = block_->media_in();
+  block_->set_media_in(block_->media_out());
+  block_->set_media_out(temp);
+}
+
+void BlockReverseCommand::undo()
+{
+  // Since it's a simple swap, we can just run redo() again
+  redo();
+}

app/dialog/speedduration/speedduration.h

@@ -44,4 +44,15 @@ private slots:
   void DurationChanged();
 };
 
+class BlockReverseCommand : public QUndoCommand {
+public:
+  BlockReverseCommand(Block* block, QUndoCommand* parent = nullptr);
+
+  virtual void redo() override;
+  virtual void undo() override;
+
+private:
+  Block* block_;
+};
+
 #endif // SPEEDDURATIONDIALOG_H

app/node/block/block.cpp

@@ -178,7 +178,17 @@ rational Block::media_length() const
 
 double Block::speed() const
 {
-  return media_length().toDouble() / length().toDouble();
+  return qAbs(media_length().toDouble() / length().toDouble());
+}
+
+bool Block::is_still() const
+{
+  return (media_in() == media_out());
+}
+
+bool Block::is_reversed() const
+{
+  return (media_out() < media_in());
 }
 
 const QString &Block::block_name() const

app/node/block/block.h

@@ -73,6 +73,8 @@ public:
 
   rational media_length() const;
   double speed() const;
+  bool is_still() const;
+  bool is_reversed() const;
 
   const QString& block_name() const;
   void set_block_name(const QString& name);

app/render/backend/audiorenderworker.cpp

@@ -70,6 +70,24 @@ NodeValueTable AudioRenderWorker::RenderBlock(const TrackOutput *track, const Ti
         samples_from_this_block = speed_adjusted_samples;
       }
 
+      if (b->is_reversed()) {
+        int sample_size = audio_params_.samples_to_bytes(1);
+        int half_buffer_sz = samples_from_this_block.size() / 2;
+        char* temp_buffer = new char[sample_size];
+
+        for (int src_index=0;src_index<half_buffer_sz;src_index+=sample_size) {
+          char* src_ptr = samples_from_this_block.data() + src_index;
+          char* dst_ptr = samples_from_this_block.data() + samples_from_this_block.size() - sample_size - src_index;
+
+          // Simple swap
+          memcpy(temp_buffer, src_ptr, sample_size);
+          memcpy(src_ptr, dst_ptr, sample_size);
+          memcpy(dst_ptr, temp_buffer, sample_size);
+        }
+
+        delete [] temp_buffer;
+      }
+
       copied_size = samples_from_this_block.size();
 
       memcpy(block_range_buffer.data()+destination_offset,