From 0f020e59b8c5c6c63af2a3891ddb431e5d99bf12 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Thu, 19 Jan 2017 12:39:15 +0100
Subject: [PATCH] Move preroll duration calc into libardour

---
 libs/ardour/ardour/session.h |  1 +
 libs/ardour/session.cc       | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 49ee8cbb7d..a295f11297 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -1001,6 +1001,7 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
 	void request_preroll_record (framepos_t);
 	framepos_t preroll_record_in () const { return _preroll_record_in; }
 	bool preroll_record_enabled () const { return _preroll_record_in >= 0; }
+	framecnt_t preroll_samples (framepos_t) const;
 
 	/* temporary hacks to allow selection to be pushed from GUI into backend.
 	   Whenever we move the selection object into libardour, these will go away.
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 27a3e63112..086edf2b45 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -2105,6 +2105,22 @@ Session::audible_frame () const
 	return std::max ((framepos_t)0, ret);
 }
 
+
+framecnt_t
+Session::preroll_samples (framepos_t pos) const
+{
+	const float pr = Config->get_preroll_seconds();
+	if (pos >= 0 && pr < 0) {
+		const Tempo& tempo = _tempo_map->tempo_at_frame (pos);
+		const Meter& meter = _tempo_map->meter_at_frame (pos);
+		return meter.frames_per_bar (tempo, frame_rate()) * -pr;
+	}
+	if (pr < 0) {
+		return 0;
+	}
+	return pr * frame_rate();
+}
+
 void
 Session::set_frame_rate (framecnt_t frames_per_second)
 {