Stop instantiating RtAudio all over the place

and instead just have a singleton.  On Windows I saw a situation where
the first instantiation would use ASIO and the second WASAPI, causing
all kinds of confusion.

7 files changed, 198 insertions, 84 deletions

diff --git a/src/wx/audio_backend.cc b/src/wx/audio_backend.cc
new file mode 100644
index 000000000..b77d2cdcd
--- /dev/null
+++ b/src/wx/audio_backend.cc
@@ -0,0 +1,77 @@
+/*
+    Copyright (C) 2024 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic 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.
+
+    DCP-o-matic 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 DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#include "audio_backend.h"
+
+
+AudioBackend* AudioBackend::_instance = nullptr;
+
+
+#ifdef DCPOMATIC_LINUX
+auto constexpr api = RtAudio::LINUX_PULSE;
+#endif
+#ifdef DCPOMATIC_WINDOWS
+auto constexpr api = RtAudio::UNSPECIFIED;
+#endif
+#ifdef DCPOMATIC_OSX
+auto constexpr api = RtAudio::MACOSX_CORE;
+#endif
+
+
+AudioBackend::AudioBackend()
+#if (RTAUDIO_VERSION_MAJOR >= 6)
+	: _rtaudio(api, boost::bind(&AudioBackend::rtaudio_error_callback, this, _2))
+#else
+	: _rtaudio(api)
+#endif
+{
+
+}
+
+
+#if (RTAUDIO_VERSION_MAJOR >= 6)
+void
+AudioBackend::rtaudio_error_callback(string const& error)
+{
+	boost::mutex::scoped_lock lm(_last_rtaudio_error_mutex);
+	_last_rtaudio_error = error;
+}
+
+string
+AudioBackend::last_rtaudio_error() const
+{
+	boost::mutex::scoped_lock lm(_last_rtaudio_error_mutex);
+	return _last_rtaudio_error;
+}
+#endif
+
+
+AudioBackend*
+AudioBackend::instance()
+{
+	if (!_instance) {
+		_instance = new AudioBackend();
+	}
+
+	return _instance;
+}
+
+
diff --git a/src/wx/audio_backend.h b/src/wx/audio_backend.h
new file mode 100644
index 000000000..cf1bbad05
--- /dev/null
+++ b/src/wx/audio_backend.h
@@ -0,0 +1,58 @@
+/*
+    Copyright (C) 2024 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic 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.
+
+    DCP-o-matic 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 DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#include <dcp/warnings.h>
+LIBDCP_DISABLE_WARNINGS
+#include <RtAudio.h>
+LIBDCP_ENABLE_WARNINGS
+
+
+
+class AudioBackend
+{
+public:
+	AudioBackend();
+
+	AudioBackend(AudioBackend const&) = delete;
+	AudioBackend& operator=(AudioBackend const&) = delete;
+
+	RtAudio& rtaudio() {
+		return _rtaudio;
+	}
+
+#if (RTAUDIO_VERSION_MAJOR >= 6)
+	std::string last_rtaudio_error() const;
+#endif
+
+	static AudioBackend* instance();
+
+private:
+	static AudioBackend* _instance;
+
+	RtAudio _rtaudio;
+
+#if (RTAUDIO_VERSION_MAJOR >= 6)
+	void rtaudio_error_callback(std::string const& error);
+	mutable boost::mutex _last_rtaudio_error_mutex;
+	std::string _last_rtaudio_error;
+#endif
+};
+
diff --git a/src/wx/config_dialog.cc b/src/wx/config_dialog.cc
index b4adc855e..bbe2278ac 100644
--- a/src/wx/config_dialog.cc
+++ b/src/wx/config_dialog.cc
@@ -19,6 +19,7 @@
 */
 
 
+#include "audio_backend.h"
 #include "audio_mapping_view.h"
 #include "check_box.h"
 #include "config_dialog.h"
@@ -880,7 +881,8 @@ SoundPage::setup ()
 	font.SetPointSize (font.GetPointSize() - 1);
 	_sound_output_details->SetFont (font);
 
-	RtAudio audio (DCPOMATIC_RTAUDIO_API);
+	auto& audio = AudioBackend::instance()->rtaudio();
+
 #if (RTAUDIO_VERSION_MAJOR >= 6)
 	for (auto device_id: audio.getDeviceIds()) {
 		auto dev = audio.getDeviceInfo(device_id);
@@ -928,7 +930,8 @@ SoundPage::sound_changed ()
 void
 SoundPage::sound_output_changed ()
 {
-	RtAudio audio (DCPOMATIC_RTAUDIO_API);
+	auto& audio = AudioBackend::instance()->rtaudio();
+
 	auto const so = get_sound_output();
 	string default_device;
 #if (RTAUDIO_VERSION_MAJOR >= 6)
@@ -957,11 +960,12 @@ SoundPage::config_changed ()
 	auto const current_so = get_sound_output ();
 	optional<string> configured_so;
 
+	auto& audio = AudioBackend::instance()->rtaudio();
+
 	if (config->sound_output()) {
 		configured_so = config->sound_output().get();
 	} else {
 		/* No configured output means we should use the default */
-		RtAudio audio (DCPOMATIC_RTAUDIO_API);
 #if (RTAUDIO_VERSION_MAJOR >= 6)
 		configured_so = audio.getDeviceInfo(audio.getDefaultOutputDevice()).name;
 #else
@@ -985,8 +989,6 @@ SoundPage::config_changed ()
 		}
 	}
 
-	RtAudio audio (DCPOMATIC_RTAUDIO_API);
-
 	map<int, wxString> apis;
 	apis[RtAudio::MACOSX_CORE]    = _("CoreAudio");
 	apis[RtAudio::WINDOWS_ASIO]   = _("ASIO");
diff --git a/src/wx/film_viewer.cc b/src/wx/film_viewer.cc
index b6f8096e8..f83e83c68 100644
--- a/src/wx/film_viewer.cc
+++ b/src/wx/film_viewer.cc
@@ -24,6 +24,7 @@
  */
 
 
+#include "audio_backend.h"
 #include "closed_captions_dialog.h"
 #include "film_viewer.h"
 #include "gl_video_view.h"
@@ -86,12 +87,7 @@ rtaudio_callback (void* out, void *, unsigned int frames, double, RtAudioStreamS
 
 
 FilmViewer::FilmViewer (wxWindow* p)
-#if (RTAUDIO_VERSION_MAJOR >= 6)
-	: _audio(DCPOMATIC_RTAUDIO_API, boost::bind(&FilmViewer::rtaudio_error_callback, this, _2))
-#else
-	: _audio (DCPOMATIC_RTAUDIO_API)
-#endif
-	, _closed_captions_dialog (new ClosedCaptionsDialog(p, this))
+	: _closed_captions_dialog (new ClosedCaptionsDialog(p, this))
 {
 #if wxCHECK_VERSION(3, 1, 0)
 	switch (Config::instance()->video_view_type()) {
@@ -242,6 +238,8 @@ FilmViewer::create_butler()
 
 	DCPOMATIC_ASSERT(_player);
 
+	auto& audio = AudioBackend::instance()->rtaudio();
+
 	_butler = std::make_shared<Butler>(
 		_film,
 		*_player,
@@ -252,7 +250,7 @@ FilmViewer::create_butler()
 		j2k_gl_optimised ? Image::Alignment::COMPACT : Image::Alignment::PADDED,
 		true,
 		j2k_gl_optimised,
-		(Config::instance()->sound() && _audio.isStreamOpen()) ? Butler::Audio::ENABLED : Butler::Audio::DISABLED
+		(Config::instance()->sound() && audio.isStreamOpen()) ? Butler::Audio::ENABLED : Butler::Audio::DISABLED
 		);
 
 	_closed_captions_dialog->set_butler (_butler);
@@ -344,8 +342,10 @@ void
 FilmViewer::suspend ()
 {
 	++_suspended;
-	if (_audio.isStreamRunning()) {
-		_audio.abortStream();
+
+	auto& audio = AudioBackend::instance()->rtaudio();
+	if (audio.isStreamRunning()) {
+		audio.abortStream();
 	}
 }
 
@@ -353,19 +353,21 @@ FilmViewer::suspend ()
 void
 FilmViewer::start_audio_stream_if_open ()
 {
-	if (_audio.isStreamOpen()) {
-		_audio.setStreamTime (_video_view->position().seconds());
+	auto& audio = AudioBackend::instance()->rtaudio();
+
+	if (audio.isStreamOpen()) {
+		audio.setStreamTime(_video_view->position().seconds());
 #if (RTAUDIO_VERSION_MAJOR >= 6)
-		if (_audio.startStream() != RTAUDIO_NO_ERROR) {
+		if (audio.startStream() != RTAUDIO_NO_ERROR) {
 			_audio_channels = 0;
 			error_dialog(
 				_video_view->get(),
-				_("There was a problem starting audio playback.  Please try another audio output device in Preferences."), std_to_wx(last_rtaudio_error())
+				_("There was a problem starting audio playback.  Please try another audio output device in Preferences."), std_to_wx(audio.last_rtaudio_error())
 				);
 		}
 #else
 		try {
-			_audio.startStream ();
+			audio.startStream ();
 		} catch (RtAudioError& e) {
 			_audio_channels = 0;
 			error_dialog (
@@ -428,9 +430,11 @@ FilmViewer::start ()
 bool
 FilmViewer::stop ()
 {
-	if (_audio.isStreamRunning()) {
+	auto& audio = AudioBackend::instance()->rtaudio();
+
+	if (audio.isStreamRunning()) {
 		/* stop stream and discard any remaining queued samples */
-		_audio.abortStream ();
+		audio.abortStream();
 	}
 
 	if (!_playing) {
@@ -618,16 +622,18 @@ FilmViewer::config_changed (Config::Property p)
 		return;
 	}
 
-	if (_audio.isStreamOpen ()) {
-		_audio.closeStream ();
+	auto& audio = AudioBackend::instance()->rtaudio();
+
+	if (audio.isStreamOpen()) {
+		audio.closeStream();
 	}
 
-	if (Config::instance()->sound() && _audio.getDeviceCount() > 0) {
+	if (Config::instance()->sound() && audio.getDeviceCount() > 0) {
 		optional<unsigned int> chosen_device_id;
 #if (RTAUDIO_VERSION_MAJOR >= 6)
 		if (Config::instance()->sound_output()) {
-			for (auto device_id: _audio.getDeviceIds()) {
-				if (_audio.getDeviceInfo(device_id).name == Config::instance()->sound_output().get()) {
+			for (auto device_id: audio.getDeviceIds()) {
+				if (audio.getDeviceInfo(device_id).name == Config::instance()->sound_output().get()) {
 					chosen_device_id = device_id;
 					break;
 				}
@@ -635,26 +641,26 @@ FilmViewer::config_changed (Config::Property p)
 		}
 
 		if (!chosen_device_id) {
-			chosen_device_id = _audio.getDefaultOutputDevice();
+			chosen_device_id = audio.getDefaultOutputDevice();
 		}
-		_audio_channels = _audio.getDeviceInfo(*chosen_device_id).outputChannels;
+		_audio_channels = audio.getDeviceInfo(*chosen_device_id).outputChannels;
 		RtAudio::StreamParameters sp;
 		sp.deviceId = *chosen_device_id;
 		sp.nChannels = _audio_channels;
 		sp.firstChannel = 0;
-		if (_audio.openStream(&sp, 0, RTAUDIO_FLOAT32, 48000, &_audio_block_size, &rtaudio_callback, this) != RTAUDIO_NO_ERROR) {
+		if (audio.openStream(&sp, 0, RTAUDIO_FLOAT32, 48000, &_audio_block_size, &rtaudio_callback, this) != RTAUDIO_NO_ERROR) {
 			_audio_channels = 0;
 			error_dialog(
 				_video_view->get(),
-				_("Could not set up audio output.  There will be no audio during the preview."), std_to_wx(last_rtaudio_error())
+				_("Could not set up audio output.  There will be no audio during the preview."), std_to_wx(audio.last_rtaudio_error())
 				);
 		}
 #else
 		unsigned int st = 0;
 		if (Config::instance()->sound_output()) {
-			while (st < _audio.getDeviceCount()) {
+			while (st < audio.getDeviceCount()) {
 				try {
-					if (_audio.getDeviceInfo(st).name == Config::instance()->sound_output().get()) {
+					if (audio.getDeviceInfo(st).name == Config::instance()->sound_output().get()) {
 						break;
 					}
 				} catch (RtAudioError&) {
@@ -662,28 +668,28 @@ FilmViewer::config_changed (Config::Property p)
 				}
 				++st;
 			}
-			if (st == _audio.getDeviceCount()) {
+			if (st == audio.getDeviceCount()) {
 				try {
-					st = _audio.getDefaultOutputDevice();
+					st = audio.getDefaultOutputDevice();
 				} catch (RtAudioError&) {
 					/* Something went wrong with that device so we don't want to use it anyway */
 				}
 			}
 		} else {
 			try {
-				st = _audio.getDefaultOutputDevice();
+				st = audio.getDefaultOutputDevice();
 			} catch (RtAudioError&) {
 				/* Something went wrong with that device so we don't want to use it anyway */
 			}
 		}
 
 		try {
-			_audio_channels = _audio.getDeviceInfo(st).outputChannels;
+			_audio_channels = audio.getDeviceInfo(st).outputChannels;
 			RtAudio::StreamParameters sp;
 			sp.deviceId = st;
 			sp.nChannels = _audio_channels;
 			sp.firstChannel = 0;
-			_audio.openStream (&sp, 0, RTAUDIO_FLOAT32, 48000, &_audio_block_size, &rtaudio_callback, this);
+			audio.openStream(&sp, 0, RTAUDIO_FLOAT32, 48000, &_audio_block_size, &rtaudio_callback, this);
 		} catch (RtAudioError& e) {
 			_audio_channels = 0;
 			error_dialog (
@@ -704,8 +710,10 @@ FilmViewer::config_changed (Config::Property p)
 DCPTime
 FilmViewer::uncorrected_time () const
 {
-	if (_audio.isStreamRunning()) {
-		return DCPTime::from_seconds (const_cast<RtAudio*>(&_audio)->getStreamTime());
+	auto& audio = AudioBackend::instance()->rtaudio();
+
+	if (audio.isStreamRunning()) {
+		return DCPTime::from_seconds(audio.getStreamTime());
 	}
 
 	return _video_view->position();
@@ -715,11 +723,13 @@ FilmViewer::uncorrected_time () const
 optional<DCPTime>
 FilmViewer::audio_time () const
 {
-	if (!_audio.isStreamRunning()) {
+	auto& audio = AudioBackend::instance()->rtaudio();
+
+	if (!audio.isStreamRunning()) {
 		return {};
 	}
 
-	return DCPTime::from_seconds (const_cast<RtAudio*>(&_audio)->getStreamTime ()) -
+	return DCPTime::from_seconds(audio.getStreamTime()) -
 		DCPTime::from_frames (average_latency(), _film->audio_frame_rate());
 }
 
@@ -743,13 +753,15 @@ FilmViewer::audio_callback (void* out_p, unsigned int frames)
 		/* The audio we just got was (very) late; drop it and get some more. */
 	}
 
-        boost::mutex::scoped_lock lm (_latency_history_mutex, boost::try_to_lock);
-        if (lm) {
-                _latency_history.push_back (_audio.getStreamLatency ());
-                if (_latency_history.size() > static_cast<size_t> (_latency_history_count)) {
-                        _latency_history.pop_front ();
-                }
-        }
+	auto& audio = AudioBackend::instance()->rtaudio();
+
+	boost::mutex::scoped_lock lm (_latency_history_mutex, boost::try_to_lock);
+	if (lm) {
+		_latency_history.push_back(audio.getStreamLatency());
+		if (_latency_history.size() > static_cast<size_t> (_latency_history_count)) {
+			_latency_history.pop_front ();
+		}
+	}
 
 	return 0;
 }
@@ -898,21 +910,3 @@ FilmViewer::unset_crop_guess ()
 	_video_view->update ();
 }
 
-
-#if (RTAUDIO_VERSION_MAJOR >= 6)
-void
-FilmViewer::rtaudio_error_callback(string const& error)
-{
-	boost::mutex::scoped_lock lm(_last_rtaudio_error_mutex);
-	_last_rtaudio_error = error;
-}
-
-
-string
-FilmViewer::last_rtaudio_error() const
-{
-	boost::mutex::scoped_lock lm(_last_rtaudio_error_mutex);
-	return _last_rtaudio_error;
-}
-#endif
-
diff --git a/src/wx/film_viewer.h b/src/wx/film_viewer.h
index 5824f8baa..a0aac62dd 100644
--- a/src/wx/film_viewer.h
+++ b/src/wx/film_viewer.h
@@ -171,13 +171,6 @@ private:
 	void ui_finished ();
 	void start_audio_stream_if_open ();
 
-#if (RTAUDIO_VERSION_MAJOR >= 6)
-	void rtaudio_error_callback(std::string const& error);
-	mutable boost::mutex _last_rtaudio_error_mutex;
-	std::string _last_rtaudio_error;
-	std::string last_rtaudio_error() const;
-#endif
-
 	dcpomatic::DCPTime uncorrected_time () const;
 	Frame average_latency () const;
 
@@ -190,7 +183,6 @@ private:
 	bool _coalesce_player_changes = false;
 	std::vector<int> _pending_player_changes;
 
-	RtAudio _audio;
 	int _audio_channels = 0;
 	unsigned int _audio_block_size = 1024;
 	bool _playing = false;
diff --git a/src/wx/wscript b/src/wx/wscript
index a6eefa69f..f52f71afc 100644
--- a/src/wx/wscript
+++ b/src/wx/wscript
@@ -26,6 +26,7 @@ import i18n
 
 sources = """
           about_dialog.cc
+          audio_backend.cc
           audio_dialog.cc
           audio_gain_dialog.cc
           audio_mapping_view.cc
diff --git a/src/wx/wx_util.h b/src/wx/wx_util.h
index 66b01640c..c85af1d4f 100644
--- a/src/wx/wx_util.h
+++ b/src/wx/wx_util.h
@@ -86,16 +86,6 @@ class PasswordEntry;
 #define DCPOMATIC_BUTTON_STACK_GAP 0
 #endif
 
-#ifdef DCPOMATIC_LINUX
-#define DCPOMATIC_RTAUDIO_API RtAudio::LINUX_PULSE
-#endif
-#ifdef DCPOMATIC_WINDOWS
-#define DCPOMATIC_RTAUDIO_API RtAudio::UNSPECIFIED
-#endif
-#ifdef DCPOMATIC_OSX
-#define DCPOMATIC_RTAUDIO_API RtAudio::MACOSX_CORE
-#endif
-
 
 /** i18n macro to support strings like Context|String
  *  so that `String' can be translated to different things