diff --git a/libs/ardour/ardour/export_channel.h b/libs/ardour/ardour/export_channel.h
index 9a570f71ba..273e2ec258 100644
--- a/libs/ardour/ardour/export_channel.h
+++ b/libs/ardour/ardour/export_channel.h
@@ -32,6 +32,7 @@
 #include "pbd/ringbuffer.h"
 #include "pbd/signals.h"
 
+#include "ardour/audio_buffer.h"
 #include "ardour/buffer_set.h"
 #include "ardour/export_pointers.h"
 
@@ -52,7 +53,7 @@ public:
 	virtual samplecnt_t common_port_playback_latency () const { return 0; }
 	virtual void prepare_export (samplecnt_t max_samples, sampleoffset_t common_latency) {}
 
-	virtual void read (Sample const*& data, samplecnt_t samples) const = 0;
+	virtual void read (Buffer const*&, samplecnt_t samples) const = 0;
 
 	virtual bool empty () const = 0;
 
@@ -78,7 +79,7 @@ public:
 	samplecnt_t common_port_playback_latency () const;
 	void        prepare_export (samplecnt_t max_samples, sampleoffset_t common_latency);
 
-	void read (Sample const*& data, samplecnt_t samples) const;
+	void read (Buffer const*&, samplecnt_t samples) const;
 
 	bool empty () const { return ports.empty (); }
 
@@ -94,6 +95,7 @@ private:
 	PortSet                                               ports;
 	samplecnt_t                                           _buffer_size;
 	boost::scoped_array<Sample>                           _buffer;
+	mutable AudioBuffer                                   _buf;
 	std::list<boost::shared_ptr<PBD::RingBuffer<Sample>>> _delaylines;
 };
 
@@ -112,7 +114,7 @@ public:
 
 	ExportChannelPtr create (uint32_t channel);
 
-	void read (uint32_t channel, Sample const*& data, samplecnt_t samples_to_read);
+	void read (uint32_t channel, Buffer const*&, samplecnt_t samples_to_read);
 
 private:
 	int new_cycle_started (samplecnt_t)
@@ -145,9 +147,9 @@ class LIBARDOUR_API RegionExportChannel : public ExportChannel
 	friend class RegionExportChannelFactory;
 
 public:
-	void read (Sample const*& data, samplecnt_t samples_to_read) const
+	void read (Buffer const*& buf, samplecnt_t samples_to_read) const
 	{
-		factory.read (channel, data, samples_to_read);
+		factory.read (channel, buf, samples_to_read);
 	}
 
 	void get_state (XMLNode* /*node*/) const {};
@@ -188,7 +190,7 @@ public:
 public: // ExportChannel interface
 	void prepare_export (samplecnt_t max_samples, sampleoffset_t common_latency);
 
-	void read (Sample const*& data, samplecnt_t samples) const;
+	void read (Buffer const*&, samplecnt_t samples) const;
 
 	bool empty () const { return false; }
 
diff --git a/libs/ardour/export_channel.cc b/libs/ardour/export_channel.cc
index f2e2587b14..e3e217f287 100644
--- a/libs/ardour/export_channel.cc
+++ b/libs/ardour/export_channel.cc
@@ -38,6 +38,7 @@ using namespace ARDOUR;
 
 PortExportChannel::PortExportChannel ()
 	: _buffer_size (0)
+	, _buf (0)
 {
 }
 
@@ -101,7 +102,7 @@ PortExportChannel::operator< (ExportChannel const& other) const
 }
 
 void
-PortExportChannel::read (Sample const*& data, samplecnt_t samples) const
+PortExportChannel::read (Buffer const*& buf, samplecnt_t samples) const
 {
 	assert (_buffer);
 	assert (samples <= _buffer_size);
@@ -109,8 +110,8 @@ PortExportChannel::read (Sample const*& data, samplecnt_t samples) const
 	if (ports.size () == 1 && _delaylines.size () == 1 && _delaylines.front ()->bufsize () == _buffer_size + 1) {
 		boost::shared_ptr<AudioPort> p = ports.begin ()->lock ();
 		AudioBuffer&                 ab (p->get_audio_buffer (samples)); // unsets AudioBuffer::_written
-		data = ab.data ();
 		ab.set_written (true);
+		buf = &ab;
 		return;
 	}
 
@@ -143,7 +144,8 @@ PortExportChannel::read (Sample const*& data, samplecnt_t samples) const
 		++di;
 	}
 
-	data = _buffer.get ();
+	_buf.set_data (_buffer.get(), samples);
+	buf = &_buf;
 }
 
 void
@@ -217,7 +219,7 @@ RegionExportChannelFactory::create (uint32_t channel)
 }
 
 void
-RegionExportChannelFactory::read (uint32_t channel, Sample const*& data, samplecnt_t samples_to_read)
+RegionExportChannelFactory::read (uint32_t channel, Buffer const*& buf, samplecnt_t samples_to_read)
 {
 	assert (channel < n_channels);
 	assert (samples_to_read <= samples_per_cycle);
@@ -227,7 +229,7 @@ RegionExportChannelFactory::read (uint32_t channel, Sample const*& data, samplec
 		buffers_up_to_date = true;
 	}
 
-	data = buffers.get_audio (channel).data ();
+	buf = &buffers.get_audio (channel);
 }
 
 void
@@ -290,7 +292,7 @@ RouteExportChannel::prepare_export (samplecnt_t max_samples, sampleoffset_t)
 }
 
 void
-RouteExportChannel::read (Sample const*& data, samplecnt_t samples) const
+RouteExportChannel::read (Buffer const*& buf, samplecnt_t samples) const
 {
 	assert (processor);
 	AudioBuffer const& buffer = processor->get_capture_buffers ().get_audio (channel);
@@ -299,7 +301,7 @@ RouteExportChannel::read (Sample const*& data, samplecnt_t samples) const
 #else
 	assert (samples <= (samplecnt_t)buffer.capacity ());
 #endif
-	data = buffer.data ();
+	buf = &buffer;
 }
 
 void
diff --git a/libs/ardour/export_graph_builder.cc b/libs/ardour/export_graph_builder.cc
index 9fdfe5bb20..dd14166b61 100644
--- a/libs/ardour/export_graph_builder.cc
+++ b/libs/ardour/export_graph_builder.cc
@@ -86,8 +86,12 @@ ExportGraphBuilder::process (samplecnt_t samples, bool last_cycle)
 
 	sampleoffset_t off = 0;
 	for (ChannelMap::iterator it = channels.begin(); it != channels.end(); ++it) {
-		Sample const * process_buffer = 0;
-		it->first->read (process_buffer, samples);
+		// TODO special case MIDI..
+		Buffer const* buf;
+		it->first->read (buf, samples);
+		AudioBuffer const* ab = dynamic_cast<AudioBuffer const*> (buf);
+		assert (ab);
+		Sample const* process_buffer = ab->data ();
 
 		if (session.remaining_latency_preroll () >= _master_align + samples) {
 			/* Skip processing during pre-roll, only read/write export ringbuffers */