diff --git a/app/audio/audiovisualwaveform.h b/app/audio/audiovisualwaveform.h
index be488169f..c7071e115 100644
--- a/app/audio/audiovisualwaveform.h
+++ b/app/audio/audiovisualwaveform.h
@@ -60,7 +60,7 @@ public:
    *
    * Starting at `start`, writes samples over anything in the buffer, expanding it if necessary.
    */
-  void OverwriteSamples(SampleBufferPtr samples, int sample_rate, const rational& start = rational());
+  void OverwriteSamples(SampleBufferPtr samples, int sample_rate, const rational& start = 0);
 
   /**
    * @brief Replaces sums at a certain range in this visual waveform
@@ -81,7 +81,7 @@ public:
    *
    * Maximum length of `sums` to overwrite with.
    */
-  void OverwriteSums(const AudioVisualWaveform& sums, const rational& dest, const rational& offset = rational(), const rational &length = rational());
+  void OverwriteSums(const AudioVisualWaveform& sums, const rational& dest, const rational& offset = 0, const rational &length = 0);
 
   void Shift(const rational& from, const rational& to);
 
diff --git a/app/common/rational.cpp b/app/common/rational.cpp
index f8702acb6..c5b537af3 100644
--- a/app/common/rational.cpp
+++ b/app/common/rational.cpp
@@ -7,24 +7,28 @@ namespace olive {
 
 rational rational::fromDouble(const double &flt, bool* ok)
 {
+  if (qIsNaN(flt)) {
+    // Return NaN rational
+    if (ok) *ok = false;
+    return rational(0, 0);
+  }
+
   // Use FFmpeg function for the time being
   AVRational r = av_d2q(flt, INT_MAX);
+
   if (r.den == 0) {
     // If den == 0, we were unable to convert to a rational
     if (ok) {
       *ok = false;
     }
-
-    return rational();
   } else {
     // Otherwise, assume we received a real rational
     if (ok) {
       *ok = true;
     }
-
-    return r;
   }
 
+  return r;
 }
 
 rational rational::fromString(const QString &str, bool* ok)
@@ -37,32 +41,32 @@ rational rational::fromString(const QString &str, bool* ok)
   case 2:
     return rational(elements.at(0).toLongLong(ok), elements.at(1).toLongLong(ok));
   default:
+    // Returns NaN with ok set to false
     if (ok) {
       *ok = false;
     }
-    return rational();
+    return rational(0, 0);
   }
 }
 
-//Function: print number to cout
-
-void rational::print(std::ostream &out) const
-{
-  out << this->numer_ << "/" << this->denom_;
-}
-
 //Function: ensures denom >= 0
 
 void rational::fix_signs()
 {
+  // Normalize so that denominator is always positive and only numerator is positive
   if (denom_ < 0) {
     denom_ = -denom_;
     numer_ = -numer_;
   }
 
-  if (numer_ == intType(0) || denom_ == intType(0)) {
+  // Normalize to 0/1 if numerator is zero
+  if (numer_ == intType(0)) {
+    denom_ = intType(1);
+  }
+
+  // Normalize to 0/0 (aka NaN) if denominator is zero
+  if (denom_ == intType(0)) {
     numer_ = intType(0);
-    denom_ = intType(0);
   }
 }
 
@@ -107,7 +111,7 @@ double rational::toDouble() const
   if (denom_ != 0) {
     return static_cast<double>(numer_) / static_cast<double>(denom_);
   } else {
-    return static_cast<double>(0);
+    return qSNaN();
   }
 }
 
@@ -137,6 +141,11 @@ rational rational::flipped() const
 }
 
 bool rational::isNull() const
+{
+  return numerator() == 0;
+}
+
+bool rational::isNaN() const
 {
   return denominator() == 0;
 }
@@ -170,15 +179,21 @@ const rational& rational::operator=(const rational &rhs)
 
 const rational& rational::operator+=(const rational &rhs)
 {
-  if (!rhs.isNull()) {
-    if (isNull()) {
-      numer_ = rhs.numer_;
-      denom_ = rhs.denom_;
-    } else {
-      numer_ = (numer_ * rhs.denom_) + (rhs.numer_ * denom_);
-      denom_ = denom_ * rhs.denom_;
+  if (!isNaN()) {
+    if (rhs.isNaN()) {
+      // Set to NaN
+      denom_ = 0;
       fix_signs();
-      reduce();
+    } else if (!rhs.isNull()) {
+      if (isNull()) {
+        numer_ = rhs.numer_;
+        denom_ = rhs.denom_;
+      } else {
+        numer_ = (numer_ * rhs.denom_) + (rhs.numer_ * denom_);
+        denom_ = denom_ * rhs.denom_;
+        fix_signs();
+        reduce();
+      }
     }
   }
 
@@ -187,15 +202,21 @@ const rational& rational::operator+=(const rational &rhs)
 
 const rational& rational::operator-=(const rational &rhs)
 {
-  if (!rhs.isNull()) {
-    if (isNull()) {
-      numer_ = -rhs.numer_;
-      denom_ = rhs.denom_;
-    } else {
-      numer_ = (numer_ * rhs.denom_) - (rhs.numer_ * denom_);
-      denom_ = denom_ * rhs.denom_;
+  if (!isNaN()) {
+    if (rhs.isNaN()) {
+      // Set to NaN
+      denom_ = 0;
       fix_signs();
-      reduce();
+    } else if (!rhs.isNull()) {
+      if (isNull()) {
+        numer_ = -rhs.numer_;
+        denom_ = rhs.denom_;
+      } else {
+        numer_ = (numer_ * rhs.denom_) - (rhs.numer_ * denom_);
+        denom_ = denom_ * rhs.denom_;
+        fix_signs();
+        reduce();
+      }
     }
   }
 
@@ -204,19 +225,36 @@ const rational& rational::operator-=(const rational &rhs)
 
 const rational& rational::operator/=(const rational &rhs)
 {
-  numer_ = numer_ * rhs.denom_;
-  denom_ = denom_ * rhs.numer_;
-  fix_signs();
-  reduce();
+  if (!isNaN()) {
+    if (rhs.isNaN()) {
+      // Set to NaN
+      denom_ = 0;
+      fix_signs();
+    } else {
+      numer_ = numer_ * rhs.denom_;
+      denom_ = denom_ * rhs.numer_;
+      fix_signs();
+      reduce();
+    }
+  }
+
   return *this;
 }
 
 const rational& rational::operator*=(const rational &rhs)
 {
-  numer_ = numer_ * rhs.numer_;
-  denom_ = denom_ * rhs.denom_;
-  fix_signs();
-  reduce();
+  if (!isNaN()) {
+    if (rhs.isNaN()) {
+      denom_ = 0;
+      fix_signs();
+    } else {
+      numer_ = numer_ * rhs.numer_;
+      denom_ = denom_ * rhs.denom_;
+      fix_signs();
+      reduce();
+    }
+  }
+
   return *this;
 }
 
@@ -254,6 +292,10 @@ rational rational::operator*(const rational &rhs) const
 
 bool rational::operator<(const rational &rhs) const
 {
+  if (isNaN() || rhs.isNaN()) {
+    return false;
+  }
+
   if (isNull() && rhs.isNull()) {
     return false;
   }
@@ -283,6 +325,10 @@ bool rational::operator<(const rational &rhs) const
 
 bool rational::operator<=(const rational &rhs) const
 {
+  if (isNaN() || rhs.isNaN()) {
+    return false;
+  }
+
   if (isNull() && rhs.isNull()) {
     return true;
   }
@@ -322,40 +368,16 @@ bool rational::operator>=(const rational &rhs) const
 
 bool rational::operator==(const rational &rhs) const
 {
+  if (isNaN() || rhs.isNaN()) {
+    return false;
+  }
+
   return (numer_ == rhs.numer_ && denom_ == rhs.denom_);
 }
 
 bool rational::operator!=(const rational &rhs) const
 {
-  return (numer_ != rhs.numer_) || (denom_ != rhs.denom_);
-}
-
-//Unary operators
-
-const rational& rational::operator++()
-{
-  numer_ += denom_;
-  return *this;
-}
-
-rational rational::operator++(int)
-{
-  rational tmp = *this;
-  numer_ += denom_;
-  return tmp;
-}
-
-const rational& rational::operator--()
-{
-  numer_ -= denom_;
-  return *this;
-}
-
-rational rational::operator--(int)
-{
-  rational tmp;
-  numer_ -= denom_;
-  return tmp;
+  return !(*this == rhs);
 }
 
 const rational& rational::operator+() const
@@ -417,8 +439,4 @@ uint qHash(const rational &r, uint seed)
 QDebug operator<<(QDebug debug, const olive::rational &r)
 {
   return debug.space() << r.toDouble();
-  /*
-  debug.nospace() << r.numerator() << "/" << r.denominator();
-  return debug.space();
-  */
 }
diff --git a/app/common/rational.h b/app/common/rational.h
index 8dd3327fa..3a3d19411 100644
--- a/app/common/rational.h
+++ b/app/common/rational.h
@@ -34,13 +34,9 @@ class rational
 public:
   //constructors
   rational(const intType &numerator = 0) :
-    numer_(numerator)
+    numer_(numerator),
+    denom_(1)
   {
-    if (numer_ == 0) {
-      denom_ = 0;
-    } else {
-      denom_ = 1;
-    }
   }
 
   rational(const intType &numerator, const intType &denominator) :
@@ -87,10 +83,6 @@ public:
   bool operator!=(const rational &rhs) const;
 
   //Unary operators
-  const rational& operator++(); //prefix
-  rational operator++(int);     //postfix
-  const rational& operator--(); //prefix
-  rational operator--(int);     //postfix
   const rational& operator+() const;
   rational operator-() const;
   bool operator!() const;
@@ -108,11 +100,13 @@ public:
   // Produce "flipped" version
   rational flipped() const;
 
-  // Returns whether the rational is null or not
+  // Returns whether the rational is valid but equal to zero or not
+  //
+  // A NaN is always a null, but a null is not always a NaN
   bool isNull() const;
 
-  //Function: print number to cout
-  void print(std::ostream &out = std::cout) const;
+  // Returns whether this rational is not a valid number
+  bool isNaN() const;
 
   //IO
   friend std::ostream& operator<<(std::ostream &out, const rational &value);
diff --git a/app/node/output/track/track.cpp b/app/node/output/track/track.cpp
index 941f80fc0..aefa8b262 100644
--- a/app/node/output/track/track.cpp
+++ b/app/node/output/track/track.cpp
@@ -40,6 +40,9 @@ const QString Track::kMutedInput = QStringLiteral("muted_in");
 
 Track::Track() :
   track_type_(Track::kNone),
+  track_length_(0),
+  midop_track_length_(0),
+  preop_track_length_(0),
   index_(-1),
   locked_(false)
 {
@@ -276,7 +279,7 @@ void Track::InputDisconnectedEvent(const QString &input, int element, const Node
     if (next) {
       UpdateInOutFrom(blocks_.indexOf(next));
     } else if (blocks_.isEmpty()) {
-      SetLengthInternal(rational());
+      SetLengthInternal(0);
     } else {
       SetLengthInternal(blocks_.last()->out());
     }
diff --git a/app/node/output/track/tracklist.cpp b/app/node/output/track/tracklist.cpp
index 4986cf583..e91321539 100644
--- a/app/node/output/track/tracklist.cpp
+++ b/app/node/output/track/tracklist.cpp
@@ -31,6 +31,7 @@ namespace olive {
 TrackList::TrackList(Sequence *parent, const Track::Type &type, const QString &track_input) :
   QObject(parent),
   track_input_(track_input),
+  total_length_(0),
   type_(type)
 {
 }
diff --git a/app/node/output/viewer/viewer.cpp b/app/node/output/viewer/viewer.cpp
index e8c16848e..afe60e4fa 100644
--- a/app/node/output/viewer/viewer.cpp
+++ b/app/node/output/viewer/viewer.cpp
@@ -37,6 +37,9 @@ const uint64_t ViewerOutput::kVideoParamEditMask = VideoParamEdit::kWidthHeight
 #define super Node
 
 ViewerOutput::ViewerOutput(bool create_default_streams) :
+  last_length_(0),
+  video_length_(0),
+  audio_length_(0),
   video_frame_cache_(this),
   audio_playback_cache_(this),
   video_cache_enabled_(true),
@@ -226,7 +229,7 @@ void ViewerOutput::InvalidateCache(const TimeRange& range, const QString& from,
 
   if ((video_cache_enabled_ && (from == kTextureInput || from == kVideoParamsInput))
       || (audio_cache_enabled_ && (from == kSamplesInput || from == kAudioParamsInput))) {
-    TimeRange invalidated_range(qMax(rational(), range.in()),
+    TimeRange invalidated_range(qMax(rational(0), range.in()),
                                 qMin(GetLength(), range.out()));
 
     if (invalidated_range.in() != invalidated_range.out()) {
@@ -297,8 +300,6 @@ void ViewerOutput::Retranslate()
 
 void ViewerOutput::VerifyLength()
 {
-  rational subtitle_length;
-
   video_length_ = VerifyLengthInternal(Track::kVideo);
   if (video_cache_enabled_) {
     video_frame_cache_.SetLength(video_length_);
@@ -309,7 +310,7 @@ void ViewerOutput::VerifyLength()
     audio_playback_cache_.SetLength(audio_length_);
   }
 
-  subtitle_length = VerifyLengthInternal(Track::kSubtitle);
+  rational subtitle_length = VerifyLengthInternal(Track::kSubtitle);
 
   rational real_length = qMax(subtitle_length, qMax(video_length_, audio_length_));
 
@@ -345,14 +346,19 @@ rational ViewerOutput::VerifyLengthInternal(Track::Type type) const
   case Track::kVideo:
     if (IsInputConnected(kTextureInput)) {
       NodeValueTable t = traverser.GenerateTable(GetConnectedOutput(kTextureInput), TimeRange(0, 0));
-      qDebug() << "Got video length:" << t.Get(NodeValue::kRational, QStringLiteral("length")).value<rational>();
-      return t.Get(NodeValue::kRational, QStringLiteral("length")).value<rational>();
+      rational r = t.Get(NodeValue::kRational, QStringLiteral("length")).value<rational>();
+      if (!r.isNaN()) {
+        return r;
+      }
     }
     break;
   case Track::kAudio:
     if (IsInputConnected(kSamplesInput)) {
       NodeValueTable t = traverser.GenerateTable(GetConnectedOutput(kSamplesInput), TimeRange(0, 0));
-      return t.Get(NodeValue::kRational, QStringLiteral("length")).value<rational>();
+      rational r = t.Get(NodeValue::kRational, QStringLiteral("length")).value<rational>();;
+      if (!r.isNaN()) {
+        return r;
+      }
     }
     break;
   case Track::kNone:
@@ -361,7 +367,7 @@ rational ViewerOutput::VerifyLengthInternal(Track::Type type) const
     break;
   }
 
-  return rational();
+  return 0;
 }
 
 NodeOutput ViewerOutput::GetConnectedTextureOutput()
diff --git a/app/node/project/footage/footage.cpp b/app/node/project/footage/footage.cpp
index dc7e112c8..9641aeb4a 100644
--- a/app/node/project/footage/footage.cpp
+++ b/app/node/project/footage/footage.cpp
@@ -196,7 +196,7 @@ rational Footage::VerifyLengthInternal(Track::Type type) const
     }
   }
 
-  return super::VerifyLengthInternal(type);
+  return 0;
 }
 
 QString Footage::GetColorspaceToUse(const VideoParams &params) const
diff --git a/app/node/project/sequence/sequence.cpp b/app/node/project/sequence/sequence.cpp
index 3e7659dd7..4517c8011 100644
--- a/app/node/project/sequence/sequence.cpp
+++ b/app/node/project/sequence/sequence.cpp
@@ -123,7 +123,7 @@ rational Sequence::VerifyLengthInternal(Track::Type type) const
     }
   }
 
-  return rational();
+  return 0;
 }
 
 void Sequence::InputConnectedEvent(const QString &input, int element, const NodeOutput &output)
diff --git a/app/render/framehashcache.cpp b/app/render/framehashcache.cpp
index ab2e65f3c..96e321e51 100644
--- a/app/render/framehashcache.cpp
+++ b/app/render/framehashcache.cpp
@@ -322,7 +322,7 @@ void FrameHashCache::ShiftEvent(const rational &from, const rational &to)
   // POSITIVE if moving forward ->
   // NEGATIVE if moving backward <-
   rational diff = to - from;
-  bool diff_is_negative = (diff < rational());
+  bool diff_is_negative = (diff < 0);
 
   QList<HashTimePair> shifted_times;
 
@@ -353,10 +353,12 @@ void FrameHashCache::ShiftEvent(const rational &from, const rational &to)
 
 void FrameHashCache::InvalidateEvent(const TimeRange &range)
 {
-  QVector<rational> invalid_frames = GetFrameListFromTimeRange({range});
+  if (!timebase_.isNull()) {
+    QVector<rational> invalid_frames = GetFrameListFromTimeRange({range});
 
-  foreach (const rational& r, invalid_frames) {
-    time_hash_map_.remove(r);
+    foreach (const rational& r, invalid_frames) {
+      time_hash_map_.remove(r);
+    }
   }
 }
 
diff --git a/app/render/playbackcache.h b/app/render/playbackcache.h
index 218955dff..391774ef5 100644
--- a/app/render/playbackcache.h
+++ b/app/render/playbackcache.h
@@ -35,7 +35,8 @@ class PlaybackCache : public QObject
   Q_OBJECT
 public:
   PlaybackCache(QObject* parent = nullptr) :
-    QObject(parent)
+    QObject(parent),
+    length_(0)
   {
   }
 
diff --git a/app/render/previewautocacher.cpp b/app/render/previewautocacher.cpp
index 373d3b278..375c700b5 100644
--- a/app/render/previewautocacher.cpp
+++ b/app/render/previewautocacher.cpp
@@ -18,8 +18,7 @@ PreviewAutoCacher::PreviewAutoCacher() :
   last_update_time_(0),
   ignore_next_mouse_button_(false)
 {
-  // Set default autocache range
-  SetPlayhead(rational());
+  SetPlayhead(0);
 
   delayed_requeue_timer_.setInterval(Config::Current()[QStringLiteral("AutoCacheDelay")].toInt());
   delayed_requeue_timer_.setSingleShot(true);
diff --git a/app/widget/timelinewidget/timelinewidget.cpp b/app/widget/timelinewidget/timelinewidget.cpp
index cacf96ccf..45ff05339 100644
--- a/app/widget/timelinewidget/timelinewidget.cpp
+++ b/app/widget/timelinewidget/timelinewidget.cpp
@@ -1224,7 +1224,7 @@ void TimelineWidget::RippleTo(Timeline::MovementMode mode)
   }
 
   // Find each track's nearest point and determine the overall timeline's nearest point
-  rational closest_point_to_playhead = (mode == Timeline::kTrimIn) ? rational() : RATIONAL_MAX;
+  rational closest_point_to_playhead = (mode == Timeline::kTrimIn) ? 0 : RATIONAL_MAX;
 
   foreach (const Timeline::EditToInfo& info, tracks) {
     if (info.nearest_block) {
diff --git a/app/widget/viewer/viewer.cpp b/app/widget/viewer/viewer.cpp
index 9e697bc88..29752c63e 100644
--- a/app/widget/viewer/viewer.cpp
+++ b/app/widget/viewer/viewer.cpp
@@ -203,7 +203,7 @@ void ViewerWidget::ConnectNodeEvent(ViewerOutput *n)
 
   SetViewerResolution(vp.width(), vp.height());
   SetViewerPixelAspect(vp.pixel_aspect_ratio());
-  last_length_ = rational();
+  last_length_ = 0;
   LengthChangedSlot(n->GetLength());
 
   ColorManager* color_manager = n->project()->color_manager();
@@ -358,7 +358,7 @@ void ViewerWidget::SetAutoCacheEnabled(bool e)
 
 void ViewerWidget::CacheEntireSequence()
 {
-  auto_cacher_.ForceCacheRange(TimeRange(rational(), GetConnectedNode()->video_frame_cache()->GetLength()));
+  auto_cacher_.ForceCacheRange(TimeRange(0, GetConnectedNode()->video_frame_cache()->GetLength()));
 }
 
 void ViewerWidget::CacheSequenceInOut()