Use the latency reported by the engine in the jack and wavfile output modules.

7 files changed, 102 insertions, 11 deletions

diff --git a/drumgizmo/drumgizmoc.cc b/drumgizmo/drumgizmoc.cc
index 6433d9d..4f3123b 100644
--- a/drumgizmo/drumgizmoc.cc
+++ b/drumgizmo/drumgizmoc.cc
@@ -383,6 +383,7 @@ int main(int argc, char* argv[])
 	}
 
 	gizmo.setSamplerate(oe->getSamplerate());
+	oe->onLatencyChange(gizmo.getLatency());
 
 	if(!gizmo.init())
 	{
diff --git a/drumgizmo/jackclient.cc b/drumgizmo/jackclient.cc
index e493e1b..fb71b1b 100644
--- a/drumgizmo/jackclient.cc
+++ b/drumgizmo/jackclient.cc
@@ -57,6 +57,12 @@ int JackClient::wrapJackProcess(jack_nframes_t nframes, void* arg)
 	return static_cast<JackClient*>(arg)->process(nframes);
 }
 
+void JackClient::latencyCallback(jack_latency_callback_mode_t mode,
+                                 void* arg)
+{
+	static_cast<JackClient*>(arg)->jackLatencyCallback(mode);
+}
+
 JackClient::JackClient()
 	: client{nullptr}
 	, processes{}
@@ -65,6 +71,12 @@ JackClient::JackClient()
 	jack_status_t status;
 	client = jack_client_open("DrumGizmo", JackNullOption, &status);
 	jack_set_process_callback(client, JackClient::wrapJackProcess, this);
+
+	// Register callback which is called by jack when it wants to know about the
+	// current port latency.
+	jack_set_latency_callback(client,
+	                          JackClient::latencyCallback,
+	                          this);
 }
 
 JackClient::~JackClient()
@@ -103,6 +115,14 @@ int JackClient::process(jack_nframes_t num_frames)
 	return 0;
 }
 
+void JackClient::jackLatencyCallback(jack_latency_callback_mode_t mode)
+{
+	for(auto& ptr : processes)
+	{
+		ptr->jackLatencyCallback(mode);
+	}
+}
+
 std::size_t JackClient::getBufferSize() const
 {
 	return jack_get_buffer_size(client);
diff --git a/drumgizmo/jackclient.h b/drumgizmo/jackclient.h
index 82cc0ed..83e5339 100644
--- a/drumgizmo/jackclient.h
+++ b/drumgizmo/jackclient.h
@@ -40,6 +40,7 @@ class JackProcess
 public:
 	virtual ~JackProcess();
 	virtual void process(jack_nframes_t num_frames) = 0;
+	virtual void jackLatencyCallback(jack_latency_callback_mode_t mode) {}
 };
 
 // --------------------------------------------------------------------
@@ -78,6 +79,8 @@ private:
 	bool is_active;
 
 	int process(jack_nframes_t num_frames);
+	void jackLatencyCallback(jack_latency_callback_mode_t mode);
 
 	static int wrapJackProcess(jack_nframes_t nframes, void* arg);
+	static void latencyCallback(jack_latency_callback_mode_t mode, void* arg);
 };
diff --git a/drumgizmo/output/jackaudio.cc b/drumgizmo/output/jackaudio.cc
index abd7d4f..75766d1 100644
--- a/drumgizmo/output/jackaudio.cc
+++ b/drumgizmo/output/jackaudio.cc
@@ -33,6 +33,7 @@ JackAudioOutputEngine::JackAudioOutputEngine(JackClient& client)
 	: AudioOutputEngine{}
 	, client(client)
 	, channels{}
+	, latency{0}
 {
 	client.add(*this);
 }
@@ -122,6 +123,11 @@ size_t JackAudioOutputEngine::getSamplerate() const
 	return client.getSampleRate();
 }
 
+void JackAudioOutputEngine::onLatencyChange(std::size_t latency)
+{
+	this->latency = latency;
+}
+
 JackAudioOutputEngine::Channel::Channel(JackClient& client,
                                         const std::string& name,
                                         std::size_t buffer_size)
@@ -130,3 +136,33 @@ JackAudioOutputEngine::Channel::Channel(JackClient& client,
 {
 	samples.resize(buffer_size);
 }
+
+void JackAudioOutputEngine::jackLatencyCallback(jack_latency_callback_mode_t mode)
+{
+	jack_latency_range_t range;
+	switch(mode)
+	{
+	case JackCaptureLatency:
+		// We do not have any audio input ports. Use this for when we do...
+//		jack_port_get_latency_range(port_feeding_input_port,
+//		                            JackPlaybackLatency,
+//		                            &range);
+//		range.min += 0;
+//		range.max += 0;
+//		jack_port_set_latency_range(input_port, JackPlaybackLatency, &range);
+		break;
+	case JackPlaybackLatency:
+		for(auto& channel : channels)
+		{
+			jack_port_get_latency_range(channel.port.port,
+			                            JackPlaybackLatency,
+			                            &range);
+			range.min += latency;
+			range.max += latency;
+			jack_port_set_latency_range(channel.port.port,
+			                            JackPlaybackLatency,
+			                            &range);
+		}
+		break;
+	}
+}
diff --git a/drumgizmo/output/jackaudio.h b/drumgizmo/output/jackaudio.h
index 324e95a..b8fbcab 100644
--- a/drumgizmo/output/jackaudio.h
+++ b/drumgizmo/output/jackaudio.h
@@ -49,11 +49,14 @@ public:
 	void post(size_t nsamples) override;
 	size_t getBufferSize() const override;
 	size_t getSamplerate() const override;
+	void onLatencyChange(std::size_t latency) override;
 
 	// based on JackProcess
 	void process(jack_nframes_t num_frames) override;
+	void jackLatencyCallback(jack_latency_callback_mode_t mode) override;
 
 private:
+
 	struct Channel
 	{
 		JackPort port;
@@ -66,4 +69,5 @@ private:
 	JackClient& client;
 	std::vector<Channel> channels;
 	Semaphore sema;
+	std::size_t latency{0};
 };
diff --git a/drumgizmo/output/wavfile.cc b/drumgizmo/output/wavfile.cc
index a9d8b0b..20b63bd 100644
--- a/drumgizmo/output/wavfile.cc
+++ b/drumgizmo/output/wavfile.cc
@@ -33,6 +33,7 @@ WavfileOutputEngine::WavfileOutputEngine()
 	, info{}
 	, channels{}
 	, file{"output"}
+	, latency{0}
 {
 	info.samplerate = 44100;
 	info.channels = 1;
@@ -69,7 +70,8 @@ bool WavfileOutputEngine::init(const Channels& data)
 	return true;
 }
 
-void WavfileOutputEngine::setParm(const std::string& parm, const std::string& value)
+void WavfileOutputEngine::setParm(const std::string& parm,
+                                  const std::string& value)
 {
 	if(parm == "file")
 	{
@@ -105,11 +107,11 @@ void WavfileOutputEngine::stop()
 {
 }
 
-void WavfileOutputEngine::pre(size_t nsamples)
+void WavfileOutputEngine::pre(std::size_t nsamples)
 {
 }
 
-void WavfileOutputEngine::run(int ch, sample_t* samples, size_t nsamples)
+void WavfileOutputEngine::run(int ch, sample_t* samples, std::size_t nsamples)
 {
 	if(static_cast<unsigned int>(ch) >= channels.size())
 	{
@@ -118,14 +120,35 @@ void WavfileOutputEngine::run(int ch, sample_t* samples, size_t nsamples)
 		return;
 	}
 
-	sf_writef_float(channels[ch], samples, nsamples);
+	// Skip the initial 'latency' samples.
+	if(nsamples <= latency)
+	{
+		return;
+	}
+
+	nsamples -= latency;
+
+	sf_writef_float(channels[ch], samples + latency, nsamples);
 }
 
-void WavfileOutputEngine::post(size_t nsamples)
+void WavfileOutputEngine::post(std::size_t nsamples)
 {
+	if(latency > nsamples)
+	{
+		latency -= nsamples;
+	}
+	else
+	{
+		latency = 0;
+	}
 }
 
-size_t WavfileOutputEngine::getSamplerate() const
+std::size_t WavfileOutputEngine::getSamplerate() const
 {
 	return info.samplerate;
 }
+
+void WavfileOutputEngine::onLatencyChange(std::size_t latency)
+{
+	this->latency = latency;
+}
diff --git a/drumgizmo/output/wavfile.h b/drumgizmo/output/wavfile.h
index dfe422c..656c0cd 100644
--- a/drumgizmo/output/wavfile.h
+++ b/drumgizmo/output/wavfile.h
@@ -25,6 +25,8 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
  */
 #pragma once
+
+#include <cstddef>
 #include <string>
 #include <vector>
 
@@ -44,15 +46,17 @@ public:
 	void setParm(const std::string& parm, const std::string& value) override;
 	bool start() override;
 	void stop() override;
-	void pre(size_t nsamples) override;
-	void run(int ch, sample_t* samples, size_t nsamples) override;
-	void post(size_t nsamples) override;
-	size_t getSamplerate() const override;
+	void pre(std::size_t nsamples) override;
+	void run(int ch, sample_t* samples, std::size_t nsamples) override;
+	void post(std::size_t nsamples) override;
+	std::size_t getSamplerate() const override;
+	void onLatencyChange(std::size_t latency) override;
 
 private:
 	SF_INFO info;
 	std::vector<SNDFILE*> channels;
-	size_t num_channels;
+	std::size_t num_channels;
 
 	std::string file;
+	std::size_t latency;
 };