Add metronome example plugin to demonstrate precise tempo sync.

5 files changed, 450 insertions, 0 deletions

diff --git a/plugins/eg-metro.lv2/manifest.ttl.in b/plugins/eg-metro.lv2/manifest.ttl.in
new file mode 100644
index 0000000..f81794f
--- /dev/null
+++ b/plugins/eg-metro.lv2/manifest.ttl.in
@@ -0,0 +1,8 @@
+@prefix lv2:  <http://lv2plug.in/ns/lv2core#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix ui:   <http://lv2plug.in/ns/extensions/ui#> .
+
+<http://lv2plug.in/plugins/eg-metro>
+	a lv2:Plugin ;
+	lv2:binary <metro@LIB_EXT@> ;
+	rdfs:seeAlso <metro.ttl> .
diff --git a/plugins/eg-metro.lv2/metro.c b/plugins/eg-metro.lv2/metro.c
new file mode 100644
index 0000000..60b61f3
--- /dev/null
+++ b/plugins/eg-metro.lv2/metro.c
@@ -0,0 +1,325 @@
+/*
+  LV2 Metronome Example Plugin
+  Copyright 2012 David Robillard <d@drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+/**
+   @file metro.c Metronome Plugin
+*/
+
+#include <math.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <stdio.h>
+
+#include "lv2/lv2plug.in/ns/ext/atom/atom.h"
+#include "lv2/lv2plug.in/ns/ext/atom/util.h"
+#include "lv2/lv2plug.in/ns/ext/time/time.h"
+#include "lv2/lv2plug.in/ns/ext/urid/urid.h"
+#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
+
+#ifndef M_PI
+#    define M_PI 3.14159265
+#endif
+
+#define EG_METRO_URI "http://lv2plug.in/plugins/eg-metro"
+
+typedef struct {
+	LV2_URID atom_Blank;
+	LV2_URID atom_Float;
+	LV2_URID atom_Path;
+	LV2_URID atom_Resource;
+	LV2_URID time_Position;
+	LV2_URID time_barBeat;
+	LV2_URID time_beatsPerMinute;
+	LV2_URID time_speed;
+} MetroURIs;
+
+static const double attack_s = 0.005;
+static const double decay_s  = 0.075;
+
+enum {
+	METRO_CONTROL = 0,
+	METRO_NOTIFY  = 1,
+	METRO_OUT     = 2
+};
+
+typedef enum {
+	STATE_ATTACK,
+	STATE_DECAY,
+	STATE_OFF
+} State;
+
+typedef struct {
+	/* Features */
+	LV2_URID_Map* map;
+
+	/* URIs */
+	MetroURIs uris;
+
+	/* Ports */
+	struct {
+		LV2_Atom_Sequence* control;
+		LV2_Atom_Sequence* notify;
+		float*             output;
+	} ports;
+
+	double   rate;
+	float    bpm;
+	float    speed;
+	uint32_t elapsed_len;  /**< Frames since last click start */
+	uint32_t wave_offset;  /**< Current play offset in wave */
+	float*   wave;         /**< One cycle of a sine wave */
+	uint32_t wave_len;     /**< Length of wave in frames */
+	uint32_t attack_len;   /**< Attack duration in frames */
+	uint32_t decay_len;    /**< Decay duration in frames */
+	State    state;        /**< Play state */
+} Metro;
+
+static void
+connect_port(LV2_Handle instance,
+             uint32_t   port,
+             void*      data)
+{
+	Metro* self = (Metro*)instance;
+
+	switch (port) {
+	case METRO_CONTROL:
+		self->ports.control = (LV2_Atom_Sequence*)data;
+		break;
+	case METRO_NOTIFY:
+		self->ports.notify = (LV2_Atom_Sequence*)data;
+		break;
+	case METRO_OUT:
+		self->ports.output = (float*)data;
+		break;
+	default:
+		break;
+	}
+}
+
+static void
+activate(LV2_Handle instance)
+{
+	Metro* self = (Metro*)instance;
+
+	self->elapsed_len = 0;
+	self->wave_offset = 0;
+	self->state       = STATE_OFF;
+}
+
+static LV2_Handle
+instantiate(const LV2_Descriptor*     descriptor,
+            double                    rate,
+            const char*               path,
+            const LV2_Feature* const* features)
+{
+	Metro* self = (Metro*)calloc(1, sizeof(Metro));
+	if (!self) {
+		return NULL;
+	}
+
+	/* Scan host features for URID map */
+	LV2_URID_Map* map = NULL;
+	for (int i = 0; features[i]; ++i) {
+		if (!strcmp(features[i]->URI, LV2_URID_URI "#map")) {
+			map = (LV2_URID_Map*)features[i]->data;
+		}
+	}
+	if (!map) {
+		fprintf(stderr, "Host does not support urid:map.\n");
+		free(self);
+		return NULL;
+	}
+
+	/* Map URIS */
+	MetroURIs* const uris = &self->uris;
+	self->map = map;
+	uris->atom_Blank          = map->map(map->handle, LV2_ATOM__Blank);
+	uris->atom_Float          = map->map(map->handle, LV2_ATOM__Float);
+	uris->atom_Path           = map->map(map->handle, LV2_ATOM__Path);
+	uris->atom_Resource       = map->map(map->handle, LV2_ATOM__Resource);
+	uris->time_Position       = map->map(map->handle, LV2_TIME__Position);
+	uris->time_barBeat        = map->map(map->handle, LV2_TIME__barBeat);
+	uris->time_beatsPerMinute = map->map(map->handle, LV2_TIME__beatsPerMinute);
+	uris->time_speed          = map->map(map->handle, LV2_TIME__speed);
+
+	/* Initialise fields */
+	self->rate       = rate;
+	self->bpm        = 120.0f;
+	self->attack_len = attack_s * rate;
+	self->decay_len  = decay_s * rate;
+	self->state      = STATE_OFF;
+
+	/* Generate one cycle of a sine wave at the desired frequency. */
+	const double freq = 440.0 * 2.0;
+	const double amp  = 0.5;
+	self->wave_len = rate / freq;
+	self->wave     = (float*)malloc(self->wave_len * sizeof(float));
+	for (uint32_t i = 0; i < self->wave_len; ++i) {
+		self->wave[i] = sin(i * 2 * M_PI * freq / rate) * amp;
+	}
+
+	return (LV2_Handle)self;
+}
+
+static void
+cleanup(LV2_Handle instance)
+{
+	free(instance);
+}
+
+static void
+play(Metro* self, uint32_t begin, uint32_t end)
+{
+	float* const   output          = self->ports.output;
+	const uint32_t frames_per_beat = 60.0f / self->bpm * self->rate;
+
+	if (self->speed == 0.0f) {
+		memset(output, 0, (end - begin) * sizeof(float));
+		return;
+	}
+
+	for (uint32_t i = begin; i < end; ++i) {
+		switch (self->state) {
+		case STATE_ATTACK:
+			/* Amplitude increases from 0..1 until attack_len */
+			output[i] = self->wave[self->wave_offset] *
+				self->elapsed_len / (float)self->attack_len;
+			if (self->elapsed_len >= self->attack_len) {
+				self->state = STATE_DECAY;
+			}
+			break;
+		case STATE_DECAY:
+			/* Amplitude decreases from 1..0 until attack_len + decay_len */
+			output[i] = 0.0f;
+			output[i] = self->wave[self->wave_offset] *
+				(1 - ((self->elapsed_len - self->attack_len) /
+				      (float)self->decay_len));
+			if (self->elapsed_len >= self->attack_len + self->decay_len) {
+				self->state = STATE_OFF;
+			}
+			break;
+		case STATE_OFF:
+			output[i] = 0.0f;
+		}
+
+		/* We continuously play the sine wave regardless of envelope */
+		self->wave_offset = (self->wave_offset + 1) % self->wave_len;
+
+		/* Update elapsed time and start attack if necessary */
+		if (++self->elapsed_len == frames_per_beat) {
+			self->state       = STATE_ATTACK;
+			self->elapsed_len = 0;
+		}
+	}
+}
+
+static void
+update_position(Metro* self, const LV2_Atom_Object* obj)
+{
+	const MetroURIs* uris = &self->uris;
+
+	/* Received new transport position/speed */
+	LV2_Atom *beat = NULL, *bpm = NULL, *speed = NULL;
+	lv2_atom_object_get(obj,
+	                    uris->time_barBeat, &beat,
+	                    uris->time_beatsPerMinute, &bpm,
+	                    uris->time_speed, &speed,
+	                    NULL);
+	if (bpm && bpm->type == uris->atom_Float) {
+		/* Tempo changed, update BPM */
+		self->bpm = ((LV2_Atom_Float*)bpm)->body;
+	}
+	if (speed && speed->type == uris->atom_Float) {
+		/* Speed changed, e.g. 0 (stop) to 1 (play) */
+		self->speed = ((LV2_Atom_Float*)speed)->body;
+	}
+	if (beat && beat->type == uris->atom_Float) {
+		/* Received a beat position, synchronize.
+		   This is a simple hard sync that may cause clicks.
+		   A real plugin would do something more graceful.
+		*/
+		const float frames_per_beat = 60.0f / self->bpm * self->rate;
+		const float bar_beats       = ((LV2_Atom_Float*)beat)->body;
+		const float beat_beats      = bar_beats - floorf(bar_beats);
+		self->elapsed_len           = beat_beats * frames_per_beat;
+		if (self->elapsed_len < self->attack_len) {
+			self->state = STATE_ATTACK;
+		} else if (self->elapsed_len < self->attack_len + self->decay_len) {
+			self->state = STATE_DECAY;
+		} else {
+			self->state = STATE_OFF;
+		}
+	}
+}
+
+static void
+run(LV2_Handle instance, uint32_t sample_count)
+{
+	Metro*           self = (Metro*)instance;
+	const MetroURIs* uris = &self->uris;
+
+	/* Work forwards in time frame by frame, handling events as we go */
+	const LV2_Atom_Sequence* in     = self->ports.control;
+	LV2_Atom_Event*          ev     = lv2_atom_sequence_begin(&in->body);
+	uint32_t                 last_t = 0;
+	for (uint32_t t = 0; t < sample_count; ++t) {
+		while (!lv2_atom_sequence_is_end(&in->body, in->atom.size, ev) &&
+		       ev->time.frames == t) {
+			/* Play the click for the time slice from last_t until now */
+			play(self, last_t, t);
+
+			if (ev->body.type == uris->atom_Blank) {
+				const LV2_Atom_Object* obj = (LV2_Atom_Object*)&ev->body;
+				if (obj->body.otype == uris->time_Position) {
+					/* Received position information, update */
+					update_position(self, obj);
+				}
+			}
+
+			/* Update time for next iteration and move to next event*/
+			last_t = t;
+			ev = lv2_atom_sequence_next(ev);
+		}
+	}
+
+	/* Play for remainder of cycle */
+	play(self, last_t, sample_count);
+}
+
+static const LV2_Descriptor descriptor = {
+	EG_METRO_URI,
+	instantiate,
+	connect_port,
+	activate,
+	run,
+	NULL,  // deactivate,
+	cleanup,
+	NULL,  // extension_data
+};
+
+LV2_SYMBOL_EXPORT const LV2_Descriptor*
+lv2_descriptor(uint32_t index)
+{
+	switch (index) {
+	case 0:
+		return &descriptor;
+	default:
+		return NULL;
+	}
+}
diff --git a/plugins/eg-metro.lv2/metro.ttl b/plugins/eg-metro.lv2/metro.ttl
new file mode 100644
index 0000000..53a3d01
--- /dev/null
+++ b/plugins/eg-metro.lv2/metro.ttl
@@ -0,0 +1,52 @@
+# LV2 Metronome Example Plugin
+# Copyright 2012 David Robillard <d@drobilla.net>
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+@prefix atom: <http://lv2plug.in/ns/ext/atom#> .
+@prefix doap: <http://usefulinc.com/ns/doap#> .
+@prefix lv2:  <http://lv2plug.in/ns/lv2core#> .
+@prefix time: <http://lv2plug.in/ns/ext/time#> .
+@prefix urid: <http://lv2plug.in/ns/ext/urid#> .
+
+<http://lv2plug.in/plugins/eg-metro>
+	a lv2:Plugin ;
+	doap:name "Example Metronome" ;
+	doap:license <http://opensource.org/licenses/isc> ;
+	lv2:project <http://lv2plug.in/ns/lv2> ;
+	lv2:requiredFeature urid:map ;
+	lv2:optionalFeature lv2:hardRTCapable ;
+	lv2:port [
+		a lv2:InputPort ,
+			atom:AtomPort ;
+		atom:bufferType atom:Sequence ;
+		atom:supports time:Position ;
+		lv2:index 0 ;
+		lv2:symbol "control" ;
+		lv2:name "Control" ;
+	] , [
+		a lv2:OutputPort ,
+			atom:AtomPort ;
+		atom:bufferType atom:Sequence ;
+		atom:supports <http://lv2plug.in/ns/ext/patch#Patch> ;
+		lv2:portProperty lv2:connectionOptional ;
+		lv2:index 1 ;
+		lv2:symbol "notify" ;
+		lv2:name "Notify" ;
+	] , [
+		a lv2:AudioPort ,
+			lv2:OutputPort ;
+		lv2:index 2 ;
+		lv2:symbol "out" ;
+		lv2:name "Out" ;
+	] .
diff --git a/plugins/eg-metro.lv2/waf b/plugins/eg-metro.lv2/waf
new file mode 120000
index 0000000..59a1ac9
--- /dev/null
+++ b/plugins/eg-metro.lv2/waf
@@ -0,0 +1 @@
+../../waf
\ No newline at end of file
diff --git a/plugins/eg-metro.lv2/wscript b/plugins/eg-metro.lv2/wscript
new file mode 100644
index 0000000..40642b6
--- /dev/null
+++ b/plugins/eg-metro.lv2/wscript
@@ -0,0 +1,64 @@
+#!/usr/bin/env python
+from waflib.extras import autowaf as autowaf
+import re
+
+# Variables for 'waf dist'
+APPNAME = 'eg-metro.lv2'
+VERSION = '1.0.0'
+
+# Mandatory variables
+top = '.'
+out = 'build'
+
+def options(opt):
+    opt.load('compiler_c')
+    autowaf.set_options(opt)
+
+def configure(conf):
+    conf.load('compiler_c')
+    autowaf.configure(conf)
+    autowaf.set_c99_mode(conf)
+    autowaf.display_header('Metro Configuration')
+
+    if not autowaf.is_child():
+        autowaf.check_pkg(conf, 'lv2', atleast_version='0.2.0', uselib_store='LV2')
+
+    autowaf.display_msg(conf, 'LV2 bundle directory', conf.env.LV2DIR)
+    print('')
+
+def build(bld):
+    bundle = 'eg-metro.lv2'
+
+    # Make a pattern for shared objects without the 'lib' prefix
+    module_pat = re.sub('^lib', '', bld.env.cshlib_PATTERN)
+    module_ext = module_pat[module_pat.rfind('.'):]
+
+    # Build manifest.ttl by substitution (for portable lib extension)
+    bld(features     = 'subst',
+        source       = 'manifest.ttl.in',
+        target       = '%s/%s' % (bundle, 'manifest.ttl'),
+        install_path = '${LV2DIR}/%s' % bundle,
+        LIB_EXT      = module_ext)
+    
+    # Copy other data files to build bundle (build/eg-metro.lv2)
+    bld(features     = 'subst',
+        is_copy      = True,
+        source       = 'metro.ttl',
+        target       = '%s/metro.ttl' % bundle,
+        install_path = '${LV2DIR}/%s' % bundle)
+
+    # Use LV2 headers from parent directory if building as a sub-project
+    includes = ['.']
+    if autowaf.is_child:
+        includes += ['../..']
+
+    # Build plugin library
+    obj = bld(features     = 'c cshlib',
+              source       = 'metro.c',
+              name         = 'metro',
+              target       = '%s/metro' % bundle,
+              install_path = '${LV2DIR}/%s' % bundle,
+              use          = 'LV2',
+              includes     = includes)
+    obj.env.cshlib_PATTERN = module_pat
+