Prototype using additional ALSA devices (w/resampling).

libs/backends/alsa/alsa_slave.h

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+/*
+ * Copyright (C) 2017 Robin Gareus <robin@gareus.org>
+ *
+ * This program 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.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef __libbackend_alsa_slave_h__
+#define __libbackend_alsa_slave_h__
+
+#include <pthread.h>
+
+#include "pbd/ringbuffer.h"
+#include "zita-resampler/vresampler.h"
+#include "zita-alsa-pcmi.h"
+
+namespace ARDOUR {
+
+class AlsaAudioSlave
+{
+public:
+	AlsaAudioSlave (
+			const char   *play_name,
+			const char   *capt_name,
+			unsigned int  master_rate,
+			unsigned int  master_samples_per_period,
+			unsigned int  slave_rate,
+			unsigned int  slave_samples_per_period,
+			unsigned int  periods_per_cycle);
+
+	virtual ~AlsaAudioSlave ();
+
+	bool start ();
+	void stop ();
+
+	void cycle_start (double, double, bool);
+	void cycle_end ();
+
+	uint32_t capt_chan (uint32_t chn, float* dst, uint32_t n_samples);
+	uint32_t play_chan (uint32_t chn, float* src, uint32_t n_samples);
+
+	bool running () const { return _active; }
+	void freewheel (bool);
+
+	int      state (void) const { return _pcmi.state (); }
+	uint32_t nplay (void) const { return _pcmi.nplay (); }
+	uint32_t ncapt (void) const { return _pcmi.ncapt (); }
+
+	PBD::Signal0<void> Halted;
+
+protected:
+	virtual void update_latencies (uint32_t, uint32_t) = 0;
+
+private:
+	Alsa_pcmi _pcmi;
+
+	static void* _process_thread (void *);
+	void* process_thread ();
+	pthread_t _thread;
+
+	bool  _run; /* keep going or stop, ardour thread */
+	bool  _active; /* is running, process thread */
+
+	/* DLL, track slave process callback */
+	double _t0, _t1;
+	uint64_t _samples_since_dll_reset;
+
+	double   _ratio;
+	uint32_t _capt_latency;
+	double   _play_latency;
+
+	volatile double _slave_speed;
+	volatile gint   _draining;
+
+	PBD::RingBuffer<float> _rb_capture;
+	PBD::RingBuffer<float> _rb_playback;
+
+	size_t _samples_per_period; // master
+
+	float* _capt_buff;
+	float* _play_buff;
+	float* _src_buff;
+
+	ArdourZita::VResampler _src_capt;
+	ArdourZita::VResampler _src_play;
+
+	static void reset_resampler (ArdourZita::VResampler&);
+
+}; // class AlsaAudioSlave
+
+} // namespace
+#endif /* __libbackend_alsa_slave_h__ */