3 files changed, 75 insertions, 1 deletions

diff --git a/libs/ardour/ardour/audiofilesource.h b/libs/ardour/ardour/audiofilesource.h
index f91f78f6d9..4daa8c24f4 100644
--- a/libs/ardour/ardour/audiofilesource.h
+++ b/libs/ardour/ardour/audiofilesource.h
@@ -20,12 +20,19 @@
 #ifndef __ardour_audiofilesource_h__ 
 #define __ardour_audiofilesource_h__
 
+#include <exception>
+
 #include <time.h>
 
 #include <ardour/audiosource.h>
 
 namespace ARDOUR {
 
+class non_existent_source : public std::exception {
+  public:
+	virtual const char *what() const throw() { return "audio file does not exist"; }
+};
+
 struct SoundFileInfo {
     float       samplerate;
     uint16_t    channels;
@@ -125,7 +132,7 @@ class AudioFileSource : public AudioSource {
 
 	/* constructor to be called for existing in-session files */
 
-	AudioFileSource (Session&, const XMLNode&);
+	AudioFileSource (Session&, const XMLNode&, bool must_exit = true);
 
 	int init (string idstr, bool must_exist);
 
diff --git a/libs/ardour/ardour/silentfilesource.h b/libs/ardour/ardour/silentfilesource.h
new file mode 100644
index 0000000000..92ef076a9b
--- /dev/null
+++ b/libs/ardour/ardour/silentfilesource.h
@@ -0,0 +1,66 @@
+/*
+    Copyright (C) 2007 Paul Davis 
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifndef __ardour_silentfilesource_h__ 
+#define __ardour_silentfilesource_h__
+
+#include <ardour/audiofilesource.h>
+
+namespace ARDOUR {
+
+class SilentFileSource : public AudioFileSource {
+  public:
+	virtual ~SilentFileSource ();
+
+	int update_header (nframes_t when, struct tm&, time_t) { return 0; }
+	int flush_header () { return 0; }
+	float sample_rate () const { return _sample_rate; }
+
+	void set_length (nframes_t len);
+	
+ 	int read_peaks (PeakData *peaks, nframes_t npeaks, nframes_t start, nframes_t cnt, double samples_per_unit) const {
+		memset (peaks, 0, sizeof (PeakData) * npeaks);
+		return 0;
+	}
+
+	bool destructive() const { return false; }
+
+  protected:
+
+	float         _sample_rate;
+
+	SilentFileSource (Session&, const XMLNode&, nframes_t nframes, float sample_rate);
+
+	friend class SourceFactory;
+
+	nframes_t read_unlocked (Sample *dst, nframes_t start, nframes_t cnt) const {
+		memset (dst, 0, sizeof (Sample) * cnt);
+		return cnt;
+	}
+
+	nframes_t write_unlocked (Sample *dst, nframes_t cnt) { return 0; }
+
+	void set_header_timeline_position () {}
+
+};
+
+} // namespace ARDOUR
+
+#endif /* __ardour_audiofilesource_h__ */
+
diff --git a/libs/ardour/ardour/source_factory.h b/libs/ardour/ardour/source_factory.h
index 207015a253..cc3863904a 100644
--- a/libs/ardour/ardour/source_factory.h
+++ b/libs/ardour/ardour/source_factory.h
@@ -20,6 +20,7 @@ class SourceFactory {
 	static sigc::signal<void,boost::shared_ptr<Source> > SourceCreated;
 
 	static boost::shared_ptr<Source> create (Session&, const XMLNode& node);
+	static boost::shared_ptr<Source> createSilent (Session&, const XMLNode& node, nframes_t nframes, float sample_rate);
 
 	// MIDI sources will have to be hacked in here somehow
 	static boost::shared_ptr<Source> createReadable (Session&, std::string path, int chn, AudioFileSource::Flag flags, bool announce = true);