From: Robin Gareus <robin@gareus.org>
Date: Wed, 31 Jul 2013 22:35:24 +0000 (+0200)
Subject: use zeroed scratch buffers for "silent" plugin runs
X-Git-Tag: 1.0.0~1135
X-Git-Url: https://main.carlh.net/gitweb/?p=ardour.git;a=commitdiff_plain;h=3e411ec4f6b99c224e61a29dd1600374f93ad8ff

use zeroed scratch buffers for "silent" plugin runs

Plugins rewrite the buffer data in-place and some plugins
can produce output even when fed with silence.

Hence, during a PluginInsert::silence() run a plugin can
inject data into the "silent" buffers which causes side-effects.

Kudos to Chris 'oofus' Goddard for finding this issue.
---

diff --git a/libs/ardour/ardour/process_thread.h b/libs/ardour/ardour/process_thread.h
index 399cd506a3..f96595fbbf 100644
--- a/libs/ardour/ardour/process_thread.h
+++ b/libs/ardour/ardour/process_thread.h
@@ -45,7 +45,7 @@ public:
 	 */
 
 	static BufferSet& get_silent_buffers (ChanCount count = ChanCount::ZERO);
-	static BufferSet& get_scratch_buffers (ChanCount count = ChanCount::ZERO);
+	static BufferSet& get_scratch_buffers (ChanCount count = ChanCount::ZERO, bool silence = false);
 	static BufferSet& get_route_buffers (ChanCount count = ChanCount::ZERO, bool silence = false);
 	static BufferSet& get_mix_buffers (ChanCount count = ChanCount::ZERO);
 	static gain_t* gain_automation_buffer ();
diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 3bd57319bb..8012970133 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -200,7 +200,7 @@ class Session : public PBD::StatefulDestructible, public PBD::ScopedConnectionLi
 	void process (pframes_t nframes);
 
 	BufferSet& get_silent_buffers (ChanCount count = ChanCount::ZERO);
-	BufferSet& get_scratch_buffers (ChanCount count = ChanCount::ZERO);
+	BufferSet& get_scratch_buffers (ChanCount count = ChanCount::ZERO, bool silence = true );
 	BufferSet& get_route_buffers (ChanCount count = ChanCount::ZERO, bool silence = true);
 	BufferSet& get_mix_buffers (ChanCount count = ChanCount::ZERO);
 
diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index 998a03e3aa..d519dbd7a7 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -448,7 +448,7 @@ PluginInsert::silence (framecnt_t nframes)
 	}
 
 	for (Plugins::iterator i = _plugins.begin(); i != _plugins.end(); ++i) {
-		(*i)->connect_and_run (_session.get_silent_buffers ((*i)->get_info()->n_inputs), in_map, out_map, nframes, 0);
+		(*i)->connect_and_run (_session.get_scratch_buffers ((*i)->get_info()->n_inputs, true), in_map, out_map, nframes, 0);
 	}
 }
 
diff --git a/libs/ardour/process_thread.cc b/libs/ardour/process_thread.cc
index 5d8d6f34fd..d4a3d2f390 100644
--- a/libs/ardour/process_thread.cc
+++ b/libs/ardour/process_thread.cc
@@ -90,7 +90,7 @@ ProcessThread::get_silent_buffers (ChanCount count)
 }
 
 BufferSet&
-ProcessThread::get_scratch_buffers (ChanCount count)
+ProcessThread::get_scratch_buffers (ChanCount count, bool silence)
 {
         ThreadBuffers* tb = _private_thread_buffers.get();
         assert (tb);
@@ -105,6 +105,14 @@ ProcessThread::get_scratch_buffers (ChanCount count)
 		sb->set_count (sb->available());
 	}
 
+	if (silence) {
+		for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
+			for (uint32_t i = 0; i < sb->count().get(*t); ++i) {
+				sb->get(*t, i).clear();
+			}
+		}
+	}
+
 	return *sb;
 }
 
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index ccc694f878..ce82f79bb5 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -4170,9 +4170,9 @@ Session::get_silent_buffers (ChanCount count)
 }
 
 BufferSet&
-Session::get_scratch_buffers (ChanCount count)
+Session::get_scratch_buffers (ChanCount count, bool silence)
 {
-	return ProcessThread::get_scratch_buffers (count);
+	return ProcessThread::get_scratch_buffers (count, silence);
 }
 
 BufferSet&