examples

commit 6c9c48853e5012285bfd0d04094d9c2c948db23a
parent 86ed3d35616d58be660771325d65f2e1e3abb0ca
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Fri, 26 Aug 2022 23:40:35 +0100

pulse: Add pulse async client

Diffstat:
M
makefile
 | 
3
++-
A
res/pluck.mono44100s16le
 | 
0

A
src/pulse-async-client.cpp
 | 
169
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 171 insertions(+), 1 deletion(-)
diff --git a/makefile b/makefile
@@ -18,8 +18,9 @@ clean:
 	$(RM) $(c_targets) $(cpp_targets)
 
 aio: -lrt
+gl-asteroids: -lglfw -lGL -lm
 io_uring: -luring
+pulse-async-client: -lpulse
 pulse-simple-client: -lpulse-simple -lm
-gl-asteroids: -lglfw -lGL -lm
 
 .PHONY: clean all all-c all-cpp
diff --git a/res/pluck.mono44100s16le b/res/pluck.mono44100s16le
Binary files differ.
diff --git a/src/pulse-async-client.cpp b/src/pulse-async-client.cpp
@@ -0,0 +1,169 @@
+#include <pulse/pulseaudio.h>
+#include <unistd.h>
+
+#include <iostream>
+#include <vector>
+#include <span>
+#include <memory>
+#include <fstream>
+
+bool ready = false;
+
+std::vector<short> sample;
+std::vector<short>::const_iterator pos;
+
+void play_sample(std::span<short> buf)
+{
+	for (auto& s : buf)
+	{
+		if (pos != sample.cend())
+			s = *pos++;
+		else
+			s = 0;
+	}
+}
+
+void wavegen(std::span<short> buf)
+{
+	static unsigned i;
+	for (auto& s : buf)
+	{
+		unsigned x;
+
+		if (i > 100)
+			x = 100 - i;
+		else
+			x = i;
+
+		x *= 2 * SHRT_MAX / 100;
+		s = x - SHRT_MAX;
+
+		if (++i > 200)
+			i = 0;
+	}
+}
+
+void pulse_state_cb(pa_context* c, void*)
+{
+	std::cout << "pulse state = " << pa_context_get_state(c) << '\n';
+	switch (pa_context_get_state(c))
+	{
+	case PA_CONTEXT_READY:
+		ready = true;
+		break;
+	}
+}
+
+void write_cb(pa_stream* s, size_t, void*)
+{
+	void* buf;
+	size_t len = -1;
+	pa_stream_begin_write(s, &buf, &len);
+
+	auto v = (short*)buf;
+	play_sample({v, len/2});
+	pa_stream_write(s, buf, len, nullptr, 0, PA_SEEK_RELATIVE);
+}
+
+void underflow_cb(pa_stream* s, void*)
+{
+	std::cout << __func__ << '\n';
+}
+
+struct mainloop
+{
+	mainloop(void)
+	:	h(pa_mainloop_new(), &pa_mainloop_free)
+	{
+		assert(h);
+	}
+
+	pa_mainloop_api* get_api(void)
+	{
+		return pa_mainloop_get_api(h.get());
+	}
+
+	operator pa_mainloop*(void)
+	{
+		return h.get();
+	}
+
+private:
+	std::unique_ptr<pa_mainloop, void(*)(pa_mainloop*)> h;
+};
+
+struct context
+{
+	context(pa_mainloop_api* api, char const* name)
+	:	h(pa_context_new_with_proplist(api, name, nullptr), pa_context_unref)
+	{
+		assert(h);
+	}
+
+	operator pa_context*(void)
+	{
+		return h.get();
+	}
+
+private:
+	std::unique_ptr<pa_context, void(*)(pa_context*)> h;
+};
+
+int main(void)
+{
+	{
+		std::ifstream file{"res/pluck.mono44100s16le", std::ios::binary | std::ios::ate};
+		assert(file);
+		auto size = file.tellg();
+		sample.resize(size/2);
+		file.seekg(0);
+		assert(file.read((char*)sample.data(), size));
+		pos = sample.cbegin();
+	}
+
+	int latency = 20000;
+
+	mainloop mainloop{};
+	auto api = mainloop.get_api();
+
+	context ctx{api, "pulse-test"};
+	assert(ctx);
+
+	pa_context_set_state_callback(ctx, pulse_state_cb, nullptr);
+	if (pa_context_connect(ctx, nullptr, PA_CONTEXT_NOAUTOSPAWN, nullptr))
+		perror("pa_context_connect");
+
+	while(not ready)
+		pa_mainloop_iterate(mainloop, 0, nullptr);
+
+	pa_sample_spec ss =
+	{
+		.format = PA_SAMPLE_S16LE,
+		.rate = 44100,
+		.channels = 1,
+	};
+	auto playstream = pa_stream_new(ctx, "playback", &ss, nullptr);
+	assert(playstream);
+	
+	pa_stream_set_write_callback(playstream, write_cb, nullptr);
+	pa_stream_set_underflow_callback(playstream, underflow_cb, nullptr);
+
+	uint32_t len = pa_usec_to_bytes(latency, &ss);
+	uint32_t minreq = pa_usec_to_bytes(0, &ss);
+	pa_buffer_attr bufattr =
+	{
+		.maxlength = (uint32_t)-1,
+		.tlength = (uint32_t)-1,
+		.prebuf = (uint32_t)-1,
+		.minreq = (uint32_t)-1,
+		.fragsize = (uint32_t)-1,
+	};
+	auto r = pa_stream_connect_playback(playstream, nullptr, &bufattr, PA_STREAM_NOFLAGS /*PA_STREAM_INTERPOLATE_TIMING | PA_STREAM_ADJUST_LATENCY | PA_STREAM_AUTO_TIMING_UPDATE*/, nullptr, nullptr);
+	assert(not r);
+
+	pa_mainloop_run(mainloop, nullptr);
+
+	pa_context_disconnect(ctx);
+
+	return 0;
+}