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impulse_pcm.c
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impulse_pcm.c
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/* alsaimpulse, a convolution filter plugin for ALSA.
* Copyright (C) 2020 Romain "Artefact2" Dal Maso <[email protected]>
*
* 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 3 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, see <https://www.gnu.org/licenses/>.
*/
#define _POSIX_C_SOURCE 200809L
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <complex.h>
#include <fftw3.h>
#include <samplerate.h>
#include <alsa/asoundlib.h>
#include <alsa/error.h>
#include <alsa/pcm_external.h>
#define MAX_CHN 16
struct channel_context {
float* impulse_data;
int impulse_length, impulse_orig_length, rate;
float orig_gain, gain;
int N; /* FFT size */
fftwf_complex* impulse_fft;
fftwf_complex* pcm_fft;
float* pcm_data;
float* ring_buffer; /* for overlapping data */
int ring_buffer_position;
fftwf_plan pcm_to_fft;
fftwf_plan fft_to_pcm;
};
struct plugin_context {
snd_pcm_extplug_t ext;
const char* wisdom_path;
bool has_clipped;
unsigned int psize, tsize; /* maximum period size, maximum transferrable size */
struct channel_context c[MAX_CHN];
};
static void add_overlap(float* restrict dest, const float* restrict src, size_t len, off_t dest_offset, float mul) {
for(size_t i = dest_offset; i < len; ++i) {
dest[i] += *(src++) * mul;
}
for(size_t i = 0; i < dest_offset; ++i) {
dest[i] += *(src++) * mul;
}
}
static snd_pcm_sframes_t transfer_callback(snd_pcm_extplug_t* ext,
const snd_pcm_channel_area_t* dst_areas, snd_pcm_uframes_t dst_offset,
const snd_pcm_channel_area_t* src_areas, snd_pcm_uframes_t src_offset,
snd_pcm_uframes_t size) {
struct plugin_context* pctx = ext->private_data;
if(size > pctx->tsize) {
/* Avoid buffer overruns, ALSA can deal with a partially fullfilled transfer just fine */
size = pctx->tsize;
}
for(int i = 0; i < ext->channels; ++i) {
struct channel_context* c = &(pctx->c[i]);
if(c->impulse_orig_length == 0) {
/* Pass through */
snd_pcm_area_copy(&(dst_areas[i]), dst_offset, &(src_areas[i]), src_offset, size, SND_PCM_FORMAT_FLOAT);
continue;
}
/* Get samples from ALSA */
snd_pcm_channel_area_t a = {
.addr = c->pcm_data,
.first = 0,
.step = sizeof(float) * 8,
};
snd_pcm_area_copy(&a, 0, &(src_areas[i]), src_offset, size, SND_PCM_FORMAT_FLOAT);
memset(&(c->pcm_data[size]), 0, sizeof(float) * (c->N - size));
/* Do the convolution */
fftwf_execute(c->pcm_to_fft);
for(int i = 0; i < c->N/2 + 1; ++i) {
c->pcm_fft[i] *= c->impulse_fft[i]; /* Complex multiplication */
}
fftwf_execute(c->fft_to_pcm);
/* Update overlaps */
add_overlap(c->ring_buffer, c->pcm_data, c->N, c->ring_buffer_position, c->gain);
/* Show clipping warning (at most once) */
if(!pctx->has_clipped) {
for(int i = 0; i < size; ++i) {
float s = c->ring_buffer[(c->ring_buffer_position + i) % (c->N)];
if(s > 1.f || s < -1.f) {
pctx->has_clipped = true;
SNDERR("clipping frame %f, consider reducing gain", s);
break;
}
}
}
/* Give samples to ALSA */
a.addr = &(c->ring_buffer[c->ring_buffer_position]);
int over = c->ring_buffer_position + size - c->N;
if(over <= 0) {
snd_pcm_area_copy(&(dst_areas[i]), dst_offset, &a, 0, size, SND_PCM_FORMAT_FLOAT);
memset(a.addr, 0, sizeof(float) * size);
c->ring_buffer_position += size;
} else {
snd_pcm_area_copy(&(dst_areas[i]), dst_offset, &a, 0, size - over, SND_PCM_FORMAT_FLOAT);
memset(a.addr, 0, sizeof(float) * (size - over));
a.addr = c->ring_buffer;
snd_pcm_area_copy(&(dst_areas[i]), dst_offset + (size - over), &a, 0, over, SND_PCM_FORMAT_FLOAT);
memset(a.addr, 0, sizeof(float) * over);
c->ring_buffer_position += size;
c->ring_buffer_position -= c->N;
}
}
return size;
}
static int hw_params_callback(snd_pcm_extplug_t* ext, snd_pcm_hw_params_t* params) {
struct plugin_context* pctx = ext->private_data;
const int plan_opts = (pctx->wisdom_path && *(pctx->wisdom_path)) ? FFTW_MEASURE : FFTW_ESTIMATE;
snd_pcm_uframes_t psize;
int ret, dir;
if((ret = snd_pcm_hw_params_get_period_size_max(params, &psize, &dir)) < 0) {
return ret;
}
if(dir == 1) {
SNDERR("could not query max period size");
return -EINVAL;
}
pctx->psize = psize;
pctx->tsize = -1;
for(int i = 0; i < MAX_CHN; ++i) {
struct channel_context* c = &(pctx->c[i]);
if(c->impulse_orig_length == 0) {
continue;
}
if(c->rate != ext->rate) {
/* Resample impulse data to hw rate */
int ret;
double ratio = (double)ext->rate / (double)c->rate;
int out_len = (int)ceil(ratio * c->impulse_orig_length);
float* out = fftwf_alloc_real(out_len);
SRC_DATA d = {
.data_in = c->impulse_data,
.input_frames = c->impulse_orig_length,
.data_out = out,
.output_frames = out_len,
.src_ratio = ratio,
};
if((ret = src_simple(&d, SRC_SINC_FASTEST, 1)) != 0) {
SNDERR("SRC error while resampling impulse: %s", src_strerror(ret));
return -EINVAL;
}
/* Normalise amplitude to avoid loudness change after convolution */
float gain = 1.f / ratio;
for(int i = 0; i < d.output_frames_gen; ++i) {
out[i] *= gain;
}
c->impulse_orig_length = d.output_frames_gen;
fftwf_free(c->impulse_data);
c->impulse_data = out;
}
if(c->impulse_fft) {
/* XXX: might be overkill to re-do everything */
fftwf_free(c->impulse_fft);
fftwf_free(c->pcm_fft);
fftwf_free(c->pcm_data);
fftwf_free(c->ring_buffer);
fftwf_destroy_plan(c->pcm_to_fft);
fftwf_destroy_plan(c->fft_to_pcm);
}
if(c->N == 0) {
c->N = 1 << (int)ceilf(log2f(c->impulse_orig_length + psize - 1));
} else if(c->N < (c->impulse_orig_length + psize - 1)) {
SNDERR("fft_size too small, should be at least %d, expect subpar results", c->impulse_orig_length + psize - 1);
} else if(c->N & (c->N - 1)) {
SNDERR("fft_size not a power of two, expect subpar performance");
}
c->gain = c->orig_gain / (c->N);
c->impulse_fft = fftwf_alloc_complex(c->N/2 + 1);
c->pcm_fft = fftwf_alloc_complex(c->N/2 + 1);
c->pcm_data = fftwf_alloc_real(c->N);
c->ring_buffer = fftwf_alloc_real(c->N);
memset(c->ring_buffer, 0, c->N * sizeof(float));
c->ring_buffer_position = 0;
c->pcm_to_fft = fftwf_plan_dft_r2c_1d(c->N, c->pcm_data, c->pcm_fft, plan_opts);
c->fft_to_pcm = fftwf_plan_dft_c2r_1d(c->N, c->pcm_fft, c->pcm_data, plan_opts);
if(c->impulse_length < c->N) {
/* Reallocate impulse_data to length N, pad zith zeroes */
float* imp = fftwf_alloc_real(c->N);
memcpy(imp, c->impulse_data, c->impulse_length * sizeof(float));
memset(&(imp[c->impulse_length]), 0, sizeof(float) * (c->N - c->impulse_length));
fftwf_free(c->impulse_data);
c->impulse_data = imp;
c->impulse_length = c->N;
}
if(pctx->tsize > c->N + 1 - c->impulse_orig_length) {
pctx->tsize = c->N + 1 - c->impulse_orig_length;
}
fftwf_plan p = fftwf_plan_dft_r2c_1d(c->N, c->impulse_data, c->impulse_fft, plan_opts);
fftwf_execute(p);
fftwf_destroy_plan(p);
}
if(pctx->wisdom_path && *(pctx->wisdom_path) && fftwf_export_wisdom_to_filename(pctx->wisdom_path) != 1) {
SNDERR("failed saving wisdom to %s, continuing anyway", pctx->wisdom_path);
}
return 0;
}
static snd_pcm_extplug_callback_t callbacks = {
.transfer = transfer_callback,
.hw_params = hw_params_callback,
};
static int copy_impulse_file(const char* path, float** out, int* out_len) {
FILE* f = fopen(path, "rb");
if(f == 0) {
SYSERR("could not open impulse file");
return -1;
}
if(fseek(f, 0, SEEK_END) < 0) {
SYSERR("could not seek in impulse file");
return -1;
}
*out_len = ftell(f) / sizeof(float);
rewind(f);
*out = fftwf_alloc_real(*out_len);
fread(*out, sizeof(float) * (*out_len), 1, f); /* XXX: check for errors/allocation success */
fclose(f);
return 0;
}
/* _snd_pcm_impulse_open(snd_pcm_t** pcmp, const char* name, snd_config_t* root, snd_config_t* conf, snd_pcm_stream_t stream, int mode) { */
SND_PCM_PLUGIN_DEFINE_FUNC(impulse) {
snd_config_iterator_t i, next;
snd_config_t* slave = 0;
snd_config_t* impulses = 0;
int ret, k;
const char* wp = 0;
/* Parse main plugin options */
snd_config_for_each(i, next, conf) {
snd_config_t* n = snd_config_iterator_entry(i);
const char* id;
if(snd_config_get_id(n, &id) < 0) continue;
if(strcmp("type", id) == 0) continue;
if(strcmp("comment", id) == 0) continue;
if(strcmp("type", id) == 0) continue;
if(strcmp("hint", id) == 0) continue;
if(strcmp("slave", id) == 0) {
slave = n;
continue;
}
if(strcmp("impulse", id) == 0) {
if(!snd_config_is_array(n)) {
SNDERR("impulse must be of type array");
return -EINVAL;
}
impulses = n;
continue;
}
if(strcmp("wisdom_path", id) == 0) {
snd_config_get_string(n, &wp);
wp = strdup(wp);
continue;
}
SNDERR("unknown config entry: %s", id);
return -EINVAL;
}
if(slave == 0) {
SNDERR("no slave config entry found");
return -EINVAL;
}
struct plugin_context* pctx = calloc(1, sizeof(struct plugin_context));
if(pctx == 0) {
SNDERR("could not allocate plugin context");
return -ENOMEM;
}
/* Parse impulse.0, impulse.1, etc. options and load impulse data */
k = 0;
snd_config_for_each(i, next, impulses) {
struct channel_context* c = &(pctx->c[k]);
snd_config_iterator_t j, next2;
snd_config_t* impulse = 0;
const char* ipath = "\0";
impulse = snd_config_iterator_entry(i);
snd_config_for_each(j, next2, impulse) {
snd_config_t* m = snd_config_iterator_entry(j);
const char* id;
if(snd_config_get_id(m, &id) < 0) continue;
if(strcmp("path", id) == 0) {
snd_config_get_string(m, &ipath);
continue;
}
if(strcmp("rate", id) == 0) {
long rate;
snd_config_get_integer(m, &rate);
c->rate = rate;
continue;
}
if(strcmp("gain", id) == 0) {
double gain = 0.0;
snd_config_get_ireal(m, &gain);
c->gain = c->orig_gain = (float)pow(1.12201845430196343559, gain);
continue;
}
if(strcmp("fft_length", id) == 0) {
long N;
snd_config_get_integer(m, &N);
c->N = N;
continue;
}
SNDERR("unknown impulse config entry: %s", id);
ret = -EINVAL;
goto abort;
}
if(k >= MAX_CHN) {
SNDERR("too many impulses specified, maximum is %d channels", MAX_CHN);
ret = -EINVAL;
goto abort;
}
if(*ipath == 0) {
/* No impulse, this means pass through this channel's samples */
/* Leave everything as zeroes */
++k;
continue;
}
if(c->rate == 0) {
SNDERR("impulse %s has no specified rate", ipath);
ret = -EINVAL;
goto abort;
}
if((ret = copy_impulse_file(ipath, &(c->impulse_data), &(c->impulse_orig_length))) < 0) {
goto abort;
}
c->impulse_length = c->impulse_orig_length;
++k;
}
pctx->ext.version = SND_PCM_EXTPLUG_VERSION;
pctx->ext.name = "impulse";
pctx->ext.callback = &callbacks;
pctx->ext.private_data = pctx;
pctx->wisdom_path = wp;
if(pctx->wisdom_path && *(pctx->wisdom_path) && fftwf_import_wisdom_from_filename(pctx->wisdom_path) != 1) {
SNDERR("failed loading wisdom from %s, continuing anyway", pctx->wisdom_path);
}
if((ret = snd_pcm_extplug_create(&(pctx->ext), name, root, slave, stream, mode)) < 0) goto abort;
*pcmp = pctx->ext.pcm;
/* Force float samples */
if((ret = snd_pcm_extplug_set_param(&(pctx->ext), SND_PCM_EXTPLUG_HW_FORMAT, SND_PCM_FORMAT_FLOAT)) < 0) goto abort;
if((ret = snd_pcm_extplug_set_slave_param(&(pctx->ext), SND_PCM_EXTPLUG_HW_FORMAT, SND_PCM_FORMAT_FLOAT)) < 0) goto abort;
return 0;
abort:
for(k = 0; k < MAX_CHN; ++k) {
if(pctx->c[k].impulse_data) {
fftwf_free(pctx->c[k].impulse_data);
}
}
if(pctx->wisdom_path) free((void*)pctx->wisdom_path);
free(pctx);
return ret;
}
SND_PCM_PLUGIN_SYMBOL(impulse);