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Diffstat (limited to 'plugins/eg-metro.lv2/metro.c')
| -rw-r--r-- | plugins/eg-metro.lv2/metro.c | 355 |
1 files changed, 355 insertions, 0 deletions
diff --git a/plugins/eg-metro.lv2/metro.c b/plugins/eg-metro.lv2/metro.c new file mode 100644 index 0000000..a7231d2 --- /dev/null +++ b/plugins/eg-metro.lv2/metro.c @@ -0,0 +1,355 @@ +/* + LV2 Metronome Example Plugin + Copyright 2012-2016 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. +*/ + +#include "lv2/atom/atom.h" +#include "lv2/atom/util.h" +#include "lv2/core/lv2.h" +#include "lv2/core/lv2_util.h" +#include "lv2/log/log.h" +#include "lv2/log/logger.h" +#include "lv2/time/time.h" +#include "lv2/urid/urid.h" + +#include <math.h> +#include <stdbool.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.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_Object; + LV2_URID atom_Path; + LV2_URID atom_Resource; + LV2_URID atom_Sequence; + 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_OUT = 1 +}; + +/** During execution this plugin can be in one of 3 states: */ +typedef enum { + STATE_ATTACK, // Envelope rising + STATE_DECAY, // Envelope lowering + STATE_OFF // Silent +} State; + +/** + This plugin must keep track of more state than previous examples to be able + to render audio. The basic idea is to generate a single cycle of a sine + wave which is conceptually played continuously. The 'tick' is generated by + enveloping the amplitude so there is a short attack/decay peak around a + tick, and silence the rest of the time. + + This example uses a simple AD envelope with fixed parameters. A more + sophisticated implementation might use a more advanced envelope and allow + the user to modify these parameters, the frequency of the wave, and so on. +*/ +typedef struct { + LV2_URID_Map* map; // URID map feature + LV2_Log_Logger logger; // Logger API + MetroURIs uris; // Cache of mapped URIDs + + struct { + LV2_Atom_Sequence* control; + float* output; + } ports; + + // Variables to keep track of the tempo information sent by the host + double rate; // Sample rate + float bpm; // Beats per minute (tempo) + float speed; // Transport speed (usually 0=stop, 1=play) + + uint32_t elapsed_len; // Frames since the start of the last click + uint32_t wave_offset; // Current play offset in the wave + State state; // Current play state + + // One cycle of a sine wave + float* wave; + uint32_t wave_len; + + // Envelope parameters + uint32_t attack_len; + uint32_t decay_len; +} 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_OUT: + self->ports.output = (float*)data; + break; + default: + break; + } +} + +/** + The activate() method resets the state completely, so the wave offset is + zero and the envelope is off. +*/ +static void +activate(LV2_Handle instance) +{ + Metro* self = (Metro*)instance; + + self->elapsed_len = 0; + self->wave_offset = 0; + self->state = STATE_OFF; +} + +/** + This plugin does a bit more work in instantiate() than the previous + examples. The tempo updates from the host contain several URIs, so those + are mapped, and the sine wave to be played needs to be generated based on + the current sample rate. +*/ +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 + const char* missing = lv2_features_query( + features, + LV2_LOG__log, &self->logger.log, false, + LV2_URID__map, &self->map, true, + NULL); + lv2_log_logger_set_map(&self->logger, self->map); + if (missing) { + lv2_log_error(&self->logger, "Missing feature <%s>\n", missing); + free(self); + return NULL; + } + + // Map URIS + MetroURIs* const uris = &self->uris; + LV2_URID_Map* const map = self->map; + uris->atom_Blank = map->map(map->handle, LV2_ATOM__Blank); + uris->atom_Float = map->map(map->handle, LV2_ATOM__Float); + uris->atom_Object = map->map(map->handle, LV2_ATOM__Object); + uris->atom_Path = map->map(map->handle, LV2_ATOM__Path); + uris->atom_Resource = map->map(map->handle, LV2_ATOM__Resource); + uris->atom_Sequence = map->map(map->handle, LV2_ATOM__Sequence); + 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 instance fields + self->rate = rate; + self->bpm = 120.0f; + self->attack_len = (uint32_t)(attack_s * rate); + self->decay_len = (uint32_t)(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 = (uint32_t)(rate / freq); + self->wave = (float*)malloc(self->wave_len * sizeof(float)); + for (uint32_t i = 0; i < self->wave_len; ++i) { + self->wave[i] = (float)(sin(i * 2 * M_PI * freq / rate) * amp); + } + + return (LV2_Handle)self; +} + +static void +cleanup(LV2_Handle instance) +{ + free(instance); +} + +/** + Play back audio for the range [begin..end) relative to this cycle. This is + called by run() in-between events to output audio up until the current time. +*/ +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; + } + } +} + +/** + Update the current position based on a host message. This is called by + run() when a time:Position is received. +*/ +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, synchronise + // This hard sync may cause clicks, a real plugin would be 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; + uint32_t last_t = 0; + for (const LV2_Atom_Event* ev = lv2_atom_sequence_begin(&in->body); + !lv2_atom_sequence_is_end(&in->body, in->atom.size, ev); + ev = lv2_atom_sequence_next(ev)) { + + // Play the click for the time slice from last_t until now + play(self, last_t, ev->time.frames); + + // Check if this event is an Object + // (or deprecated Blank to tolerate old hosts) + if (ev->body.type == uris->atom_Object || + ev->body.type == uris->atom_Blank) { + const LV2_Atom_Object* obj = (const 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 = ev->time.frames; + } + + // 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; + } +} |