diff --git a/src/stream.cpp b/src/stream.cpp
--- a/src/stream.cpp
+++ b/src/stream.cpp
@@ -20,6 +20,7 @@
 #include "stream.h"
 #include "ringbuffer.h"
 #include "indexbuffer.h"
+#include "linindexbuffer.h"
 
 Stream::Stream(unsigned nc, bool x, unsigned ns) :
     _infoModel(nc)
@@ -27,15 +28,20 @@ Stream::Stream(unsigned nc, bool x, unsi
     _numSamples = ns;
     _paused = false;
 
+    xAsIndex = true;
+    xMin = 0;
+    xMax = 1;
+
     // create xdata buffer
     _hasx = x;
     if (x)
     {
-        xData = new RingBuffer(ns);
+        // TODO: implement XRingBuffer (binary search)
+        Q_ASSERT(false);
     }
     else
     {
-        xData = new IndexBuffer(ns);
+        xData = makeXBuffer();
     }
 
     // create channels
@@ -81,6 +87,16 @@ StreamChannel* Stream::channel(unsigned 
     return const_cast<StreamChannel*>(static_cast<const Stream&>(*this).channel(index));
 }
 
+QVector<const StreamChannel*> Stream::allChannels() const
+{
+    QVector<const StreamChannel*> result(numChannels());
+    for (unsigned ci = 0; ci < numChannels(); ci++)
+    {
+        result[ci] = channel(ci);
+    }
+    return result;
+}
+
 const ChannelInfoModel* Stream::infoModel() const
 {
     return &_infoModel;
@@ -118,11 +134,12 @@ void Stream::setNumChannels(unsigned nc,
     {
         if (x)
         {
-            xData = new RingBuffer(_numSamples);
+            // TODO: implement XRingBuffer (binary search)
+            Q_ASSERT(false);
         }
         else
         {
-            xData = new IndexBuffer(_numSamples);
+            xData = makeXBuffer();
         }
 
         for (auto c : channels)
@@ -142,6 +159,18 @@ void Stream::setNumChannels(unsigned nc,
     Sink::setNumChannels(nc, x);
 }
 
+XFrameBuffer* Stream::makeXBuffer() const
+{
+    if (xAsIndex)
+    {
+        return new IndexBuffer(_numSamples);
+    }
+    else
+    {
+        return new LinIndexBuffer(_numSamples, xMin, xMax);
+    }
+}
+
 const SamplePack* Stream::applyGainOffset(const SamplePack& pack) const
 {
     Q_ASSERT(infoModel()->gainOrOffsetEn());
@@ -191,7 +220,9 @@ void Stream::feedIn(const SamplePack& pa
     unsigned ns = pack.numSamples();
     if (_hasx)
     {
-        static_cast<RingBuffer*>(xData)->addSamples(pack.xData(), ns);
+        // TODO: implement XRingBuffer (binary search)
+        Q_ASSERT(false);
+        // static_cast<RingBuffer*>(xData)->addSamples(pack.xData(), ns);
     }
 
     // modified pack that gain and offset is applied to
@@ -237,6 +268,24 @@ void Stream::setNumSamples(unsigned valu
     }
 }
 
+void Stream::setXAxis(bool asIndex, double min, double max)
+{
+    xAsIndex = asIndex;
+    xMin = min;
+    xMax = max;
+
+    // Note that x axis scaling is ignored when X is provided from source as data
+    // TODO: assert (UI options for x axis should be disabled)
+    if (!hasX())
+    {
+        xData = makeXBuffer();
+        for (auto c : channels)
+        {
+            c->setX(xData);
+        }
+    }
+}
+
 void Stream::saveSettings(QSettings* settings) const
 {
     _infoModel.saveSettings(settings);