diff --git a/libs/ardour/ardour/disk_writer.h b/libs/ardour/ardour/disk_writer.h
index 578e60a56b..4af86e25c1 100644
--- a/libs/ardour/ardour/disk_writer.h
+++ b/libs/ardour/ardour/disk_writer.h
@@ -22,6 +22,7 @@
 
 #include <list>
 #include <vector>
+#include <boost/optional.hpp>
 
 #include "pbd/g_atomic_compat.h"
 
@@ -93,8 +94,9 @@ public:
 	void mark_capture_xrun ();
 
 	/** @return Start position of currently-running capture (in session samples) */
-	samplepos_t current_capture_start () const { return _capture_start_sample; }
-	samplepos_t current_capture_end () const { return _capture_start_sample + _capture_captured; }
+	samplepos_t current_capture_start () const;
+	samplepos_t current_capture_end () const;
+
 	samplepos_t get_capture_start_sample (uint32_t n = 0) const;
 	samplecnt_t get_captured_samples (uint32_t n = 0) const;
 
@@ -145,8 +147,6 @@ protected:
 private:
 	static samplecnt_t _chunk_samples;
 
-	void prepare_record_status (samplepos_t /*capture_start_sample*/);
-
 	int add_channel_to (boost::shared_ptr<ChannelList>, uint32_t how_many);
 
 	void engage_record_enable ();
@@ -169,7 +169,8 @@ private:
 	CaptureInfos                 capture_info;
 	mutable Glib::Threads::Mutex capture_info_lock;
 
-	samplepos_t   _capture_start_sample;
+	boost::optional<samplepos_t> _capture_start_sample;
+
 	samplecnt_t   _capture_captured;
 	bool          _was_recording;
 	bool          _xrun_flag;
diff --git a/libs/ardour/disk_writer.cc b/libs/ardour/disk_writer.cc
index 8583431cc2..ae50d69fce 100644
--- a/libs/ardour/disk_writer.cc
+++ b/libs/ardour/disk_writer.cc
@@ -48,7 +48,6 @@ PBD::Signal0<void> DiskWriter::Overrun;
 
 DiskWriter::DiskWriter (Session& s, Track& t, string const & str, DiskIOProcessor::Flag f)
 	: DiskIOProcessor (s, t, X_("recorder:") + str, f)
-	, _capture_start_sample (0)
 	, _capture_captured (0)
 	, _was_recording (false)
 	, _xrun_flag (false)
@@ -174,7 +173,7 @@ DiskWriter::check_record_status (samplepos_t transport_sample, double speed, boo
 			_capture_start_sample = _session.transport_sample ();
 		}
 
-		_first_recordable_sample = _capture_start_sample;
+		_first_recordable_sample = _capture_start_sample.value ();
 
 		if (_alignment_style == ExistingMaterial) {
 			_first_recordable_sample += _capture_offset + _playback_offset;
@@ -198,7 +197,7 @@ DiskWriter::check_record_status (samplepos_t transport_sample, double speed, boo
 		                                                      name(),
 		                                                      transport_sample,
 		                                                      _session.transport_sample(),
-																													_capture_start_sample,
+																													_capture_start_sample.value (),
 																													_first_recordable_sample,
 																													_last_recordable_sample,
 		                                                      _input_latency,
@@ -209,8 +208,6 @@ DiskWriter::check_record_status (samplepos_t transport_sample, double speed, boo
 		                                                      _session.worst_input_latency()));
 
 
-		prepare_record_status (_capture_start_sample);
-
 	}
 
 	_last_possibly_recording = possibly_recording;
@@ -297,12 +294,30 @@ DiskWriter::get_capture_start_sample (uint32_t n) const
 	if (capture_info.size() > n) {
 		/* this is a completed capture */
 		return capture_info[n]->start;
-	} else {
+	} else if (_capture_start_sample) {
 		/* this is the currently in-progress capture */
-		return _capture_start_sample;
+		return _capture_start_sample.value ();
+	} else {
+		/* pre-roll, count-in etc */
+		return _session.transport_sample(); /* mild lie */
 	}
 }
 
+samplepos_t
+DiskWriter::current_capture_start () const
+{
+	if (!_capture_start_sample) {
+		return _session.transport_sample(); /* mild lie */
+	}
+	return _capture_start_sample.value ();
+}
+
+samplepos_t
+DiskWriter::current_capture_end () const
+{
+	return current_capture_start () + _capture_captured;
+}
+
 ARDOUR::samplecnt_t
 DiskWriter::get_captured_samples (uint32_t n) const
 {
@@ -366,11 +381,6 @@ DiskWriter::non_realtime_locate (samplepos_t position)
 }
 
 
-void
-DiskWriter::prepare_record_status (samplepos_t _capture_start_sample)
-{
-}
-
 /** Do some record stuff [not described in this comment!]
  *
  *  Also:
@@ -485,7 +495,8 @@ DiskWriter::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_samp
 			}
 
 			if (_midi_write_source) {
-				_midi_write_source->mark_write_starting_now (_capture_start_sample, _capture_captured, loop_length);
+				assert (_capture_start_sample);
+				_midi_write_source->mark_write_starting_now (_capture_start_sample.value (), _capture_captured, loop_length);
 			}
 
 			g_atomic_int_set (&_samples_pending_write, 0);
@@ -501,7 +512,7 @@ DiskWriter::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_samp
 		 */
 		if (rec_nframes) {
 			_accumulated_capture_offset += rec_offset;
-		} else if (start_sample >= _capture_start_sample) {
+		} else if (_capture_start_sample && start_sample >= _capture_start_sample.value ()) {
 			_accumulated_capture_offset += nframes;
 		}
 
@@ -695,9 +706,10 @@ DiskWriter::finish_capture (boost::shared_ptr<ChannelList> c)
 
 	CaptureInfo* ci = new CaptureInfo ();
 
-	ci->start =  _capture_start_sample;
+	assert (_capture_start_sample);
+	ci->start   =  _capture_start_sample.value ();
 	ci->samples = _capture_captured;
-	ci->xruns = _xruns;
+	ci->xruns   = _xruns;
 	_xruns.clear ();
 
 	if (_loop_location) {
@@ -1256,7 +1268,7 @@ DiskWriter::transport_stopped_wallclock (struct tm& when, time_t twhen, bool abo
 	}
 
 	capture_info.clear ();
-	_capture_start_sample = 0;
+	_capture_start_sample.reset ();
 }
 
 void