From e12d8b3769ab688f10d5a34b86a6bfa4102faaf6 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Tue, 25 Mar 2025 03:02:06 +0100
Subject: [PATCH] Add API to tap signal from a Delivery to RTA

Rater than having each Delivery Object provide a Ringbuffer,
which is unused most of the time, the GUI will provide
them on demand.

We need to be careful of lifetime, and use `rt_safe_delete` in
case the Delivery holds the last instance.
---
 libs/ardour/ardour/delivery.h | 18 +++++++++++++++--
 libs/ardour/delivery.cc       | 37 +++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/libs/ardour/ardour/delivery.h b/libs/ardour/ardour/delivery.h
index 4cba84788a..1b6314fa6f 100644
--- a/libs/ardour/ardour/delivery.h
+++ b/libs/ardour/ardour/delivery.h
@@ -24,6 +24,8 @@
 
 #include <string>
 
+#include "pbd/ringbuffer.h"
+
 #include "ardour/libardour_visibility.h"
 #include "ardour/types.h"
 #include "ardour/chan_count.h"
@@ -110,6 +112,17 @@ public:
 
 	void set_gain_control (std::shared_ptr<GainControl> gc);
 
+	using RTARingBuffer    = PBD::RingBuffer<ARDOUR::Sample>;
+	using RTARingBufferPtr = std::shared_ptr<RTARingBuffer>;
+	using RTABufferList    = std::vector<RTARingBufferPtr>;
+	using RTABufferListPtr = std::shared_ptr<RTABufferList>;
+
+	void set_analysis_buffers (RTABufferListPtr rb) {
+		_rtabuffers = rb;
+	}
+	bool analysis_active () const;
+	void set_analysis_active (bool);
+
 	void set_polarity_control (std::shared_ptr<AutomationControl> ac) {
 		_polarity_control = ac;
 	}
@@ -152,6 +165,9 @@ private:
 	std::shared_ptr<GainControl>       _gain_control;
 	std::shared_ptr<AutomationControl> _polarity_control;
 
+	RTABufferListPtr  _rtabuffers;
+	std::atomic<bool> _rta_active;
+
 	static bool panners_legal;
 	static PBD::Signal<void()> PannersLegal;
 
@@ -164,5 +180,3 @@ private:
 
 
 } // namespace ARDOUR
-
-
diff --git a/libs/ardour/delivery.cc b/libs/ardour/delivery.cc
index 4433d18efc..4c84e960c8 100644
--- a/libs/ardour/delivery.cc
+++ b/libs/ardour/delivery.cc
@@ -63,6 +63,7 @@ Delivery::Delivery (Session& s, std::shared_ptr<IO> io, std::shared_ptr<Pannable
 	, _current_gain (GAIN_COEFF_ZERO)
 	, _no_outs_cuz_we_no_monitor (false)
 	, _mute_master (mm)
+	, _rta_active (false)
 	, _no_panner_reset (false)
 {
 	if (pannable) {
@@ -87,6 +88,7 @@ Delivery::Delivery (Session& s, std::shared_ptr<Pannable> pannable, std::shared_
 	, _current_gain (GAIN_COEFF_ZERO)
 	, _no_outs_cuz_we_no_monitor (false)
 	, _mute_master (mm)
+	, _rta_active (false)
 	, _no_panner_reset (false)
 {
 	if (pannable) {
@@ -199,6 +201,19 @@ Delivery::set_gain_control (std::shared_ptr<GainControl> gc) {
 	}
 }
 
+bool
+Delivery::analysis_active () const
+{
+	return _rta_active.load ();
+}
+
+void
+Delivery::set_analysis_active (bool en)
+{
+	// TODO latch with session wide enable, sync'ed at process start
+	_rta_active.store (en);
+}
+
 /** Caller must hold process lock */
 bool
 Delivery::configure_io (ChanCount in, ChanCount out)
@@ -299,6 +314,14 @@ Delivery::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_sample
 			bufs.set_count (output_buffers().count ());
 			Amp::apply_simple_gain (bufs, nframes, GAIN_COEFF_ZERO);
 		}
+
+		RTABufferListPtr rtabuffers = _rtabuffers;
+		if (_rta_active.load () && rtabuffers && !rtabuffers->empty ()) {
+			BufferSet& silent_bufs = _session.get_silent_buffers(ChanCount(DataType::AUDIO, 1));
+			for (auto const& rb : *rtabuffers) {
+				rb->write (silent_bufs.get_audio(0).data(), nframes);
+			}
+		}
 		return;
 
 	} else if (tgain != GAIN_COEFF_UNITY) {
@@ -320,6 +343,20 @@ Delivery::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_sample
 		_amp->run (bufs, start_sample, end_sample, speed, nframes, true);
 	}
 
+	RTABufferListPtr rtabuffers = _rtabuffers;
+	if (_rta_active.load () && rtabuffers && !rtabuffers->empty ()) {
+		uint32_t n_audio = bufs.count().n_audio();
+		uint32_t n = 0;
+		for (auto const& rb: *rtabuffers) {
+			if (n < n_audio) {
+				rb->write (bufs.get_audio (n++).data(), nframes);
+			} else {
+				BufferSet& silent_bufs = _session.get_silent_buffers(ChanCount(DataType::AUDIO, 1));
+				rb->write (silent_bufs.get_audio(0).data(), nframes);
+			}
+		}
+	}
+
 	// Panning
 
 	if (_panshell && !_panshell->bypassed() && _panshell->panner()) {