/* -*- linux-c -*- Copyright (C) 2004 Tom Szilagyi 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. $Id: tap_limiter.c,v 1.6 2012/07/08 14:19:35 tszilagyi Exp $ */ #include #include #include #include #include #include "tap_utils.h" /* The Unique ID of the plugin: */ #define ID_MONO 2145 /* The port numbers for the plugin: */ #define LIMIT_VOL 0 #define OUT_VOL 1 #define LATENCY 2 #define INPUT 3 #define OUTPUT 4 /* Total number of ports */ #define PORTCOUNT_MONO 5 /* Size of a ringbuffer that must be large enough to hold audio * between two zero-crosses in any case (or you'll hear * distortion). 40 Hz sound at 192kHz yields a half-period of 2400 * samples, so this should be enough. */ #define RINGBUF_SIZE 2500 /* The structure used to hold port connection information and state */ typedef struct { float * limit_vol; float * out_vol; float * latency; float * input; float * output; float * ringbuffer; unsigned long buflen; unsigned long pos; unsigned long ready_num; double sample_rate; } Limiter; /* Construct a new plugin instance. */ LV2_Handle instantiate_Limiter(const LV2_Descriptor * Descriptor, double sample_rate, const char* bundle_path, const LV2_Feature* const* features) { LV2_Handle * ptr; if ((ptr = malloc(sizeof(Limiter))) != NULL) { ((Limiter *)ptr)->sample_rate = sample_rate; if ((((Limiter *)ptr)->ringbuffer = calloc(RINGBUF_SIZE, sizeof(float))) == NULL) return NULL; /* 80 Hz is the lowest frequency with which zero-crosses were * observed to occur (this corresponds to 40 Hz signal frequency). */ ((Limiter *)ptr)->buflen = ((Limiter *)ptr)->sample_rate / 80; ((Limiter *)ptr)->pos = 0; ((Limiter *)ptr)->ready_num = 0; return ptr; } return NULL; } void activate_Limiter(LV2_Handle Instance) { Limiter * ptr = (Limiter *)Instance; unsigned long i; for (i = 0; i < RINGBUF_SIZE; i++) ptr->ringbuffer[i] = 0.0f; } void deactivate_Limiter(LV2_Handle Instance) { } /* Connect a port to a data location. */ void connect_port_Limiter(LV2_Handle Instance, uint32_t Port, void * DataLocation) { Limiter * ptr = (Limiter *)Instance; switch (Port) { case LIMIT_VOL: ptr->limit_vol = (float*) DataLocation; break; case OUT_VOL: ptr->out_vol = (float*) DataLocation; break; case LATENCY: ptr->latency = (float*) DataLocation; // *(ptr->latency) = ptr->buflen; /* IS THIS LEGAL? */ break; case INPUT: ptr->input = (float*) DataLocation; break; case OUTPUT: ptr->output = (float*) DataLocation; break; } } void run_Limiter(LV2_Handle Instance, uint32_t SampleCount) { Limiter * ptr = (Limiter *)Instance; float * input = ptr->input; float * output = ptr->output; float limit_vol = db2lin(LIMIT(*(ptr->limit_vol),-30.0f,20.0f)); float out_vol = db2lin(LIMIT(*(ptr->out_vol),-30.0f,20.0f)); unsigned long sample_index; unsigned long sample_count = SampleCount; unsigned long index_offs = 0; unsigned long i; float max_value = 0; float section_gain = 0; unsigned long run_length; unsigned long total_length = 0; while (total_length < sample_count) { run_length = ptr->buflen; if (total_length + run_length > sample_count) run_length = sample_count - total_length; while (ptr->ready_num < run_length) { if (read_buffer(ptr->ringbuffer, ptr->buflen, ptr->pos, ptr->ready_num) >= 0.0f) { index_offs = 0; do { index_offs++; if (ptr->ready_num + index_offs == run_length) { /* * No more zero-crossing point in this chunk. * Fetch more samples unless we are at the last one. */ if (ptr->ready_num != 0) { run_length = ptr->ready_num; goto push; } break; } } while (read_buffer(ptr->ringbuffer, ptr->buflen, ptr->pos, ptr->ready_num + index_offs) >= 0.0f); } else { index_offs = 0; do { index_offs++; if (ptr->ready_num + index_offs == run_length) { /* * No more zero-crossing point in this chunk. * Fetch more samples unless we are at the last one. */ if (ptr->ready_num != 0) { run_length = ptr->ready_num; goto push; } break; } } while (read_buffer(ptr->ringbuffer, ptr->buflen, ptr->pos, ptr->ready_num + index_offs) < 0.0f); } /* search for max value in scanned halfcycle */ max_value = 0; for (i = ptr->ready_num; i < ptr->ready_num + index_offs; i++) { if (fabs(read_buffer(ptr->ringbuffer, ptr->buflen, ptr->pos, i)) > max_value) max_value = fabs(read_buffer(ptr->ringbuffer, ptr->buflen, ptr->pos, i)); } section_gain = limit_vol / max_value; if (max_value > limit_vol) for (i = ptr->ready_num; i < ptr->ready_num + index_offs; i++) { write_buffer(read_buffer(ptr->ringbuffer, ptr->buflen, ptr->pos, i) * section_gain, ptr->ringbuffer, ptr->buflen, ptr->pos, i); } ptr->ready_num += index_offs; } push: /* push run_length values out of ringbuffer, feed with input */ for (sample_index = 0; sample_index < run_length; sample_index++) { *(output++) = out_vol * push_buffer(*(input++), ptr->ringbuffer, ptr->buflen, &(ptr->pos)); } ptr->ready_num -= run_length; total_length += run_length; } *(ptr->latency) = ptr->buflen; } void cleanup_Limiter(LV2_Handle Instance) { free(Instance); } const void* extension_data_Limiter(const char* uri) { return NULL; } static const LV2_Descriptor Descriptor = { "http://moddevices.com/plugins/tap/limiter", instantiate_Limiter, connect_port_Limiter, activate_Limiter, run_Limiter, deactivate_Limiter, cleanup_Limiter, extension_data_Limiter }; LV2_SYMBOL_EXPORT const LV2_Descriptor* lv2_descriptor(uint32_t index) { if (index == 0) return &Descriptor; else return NULL; }