From 2f17c8c0e0dda285c35c1048454190c90c142b24 Mon Sep 17 00:00:00 2001
From: falkTX <falktx@falktx.com>
Date: Mon, 15 Mar 2021 11:09:48 +0000
Subject: eg-sampler: Add resampling via libsamplerate

---
 plugins/eg-sampler.lv2/meson.build |  8 +++++--
 plugins/eg-sampler.lv2/sampler.c   | 49 ++++++++++++++++++++++++++++++++++----
 2 files changed, 50 insertions(+), 7 deletions(-)

(limited to 'plugins')

diff --git a/plugins/eg-sampler.lv2/meson.build b/plugins/eg-sampler.lv2/meson.build
index fe9c2fd..1283a8f 100644
--- a/plugins/eg-sampler.lv2/meson.build
+++ b/plugins/eg-sampler.lv2/meson.build
@@ -5,16 +5,20 @@ plugin_sources = files('sampler.c')
 bundle_name = 'eg-sampler.lv2'
 data_filenames = ['manifest.ttl.in', 'sampler.ttl', 'click.wav']
 
+samplerate_dep = dependency('samplerate',
+                            version: '>= 0.1.0',
+                            required: get_option('plugins'))
+
 sndfile_dep = dependency('sndfile',
                          version: '>= 1.0.0',
                          required: get_option('plugins'))
 
-if sndfile_dep.found()
+if samplerate_dep.found() and sndfile_dep.found()
   module = shared_library(
     'sampler',
     plugin_sources,
     c_args: c_suppressions,
-    dependencies: [lv2_dep, m_dep, sndfile_dep],
+    dependencies: [lv2_dep, m_dep, samplerate_dep, sndfile_dep],
     gnu_symbol_visibility: 'hidden',
     install: true,
     install_dir: lv2dir / bundle_name,
diff --git a/plugins/eg-sampler.lv2/sampler.c b/plugins/eg-sampler.lv2/sampler.c
index a3ef5c3..c978d2b 100644
--- a/plugins/eg-sampler.lv2/sampler.c
+++ b/plugins/eg-sampler.lv2/sampler.c
@@ -33,6 +33,7 @@
 #include "lv2/urid/urid.h"
 #include "lv2/worker/worker.h"
 
+#include <samplerate.h>
 #include <sndfile.h>
 
 #include <math.h>
@@ -80,6 +81,7 @@ typedef struct {
   bool       activated;
   bool       gain_changed;
   bool       sample_changed;
+  int        sample_rate;
 } Sampler;
 
 /**
@@ -120,7 +122,7 @@ convert_to_mono(float* data, sf_count_t num_input_frames, uint32_t channels)
    not modified.
 */
 static Sample*
-load_sample(LV2_Log_Logger* logger, const char* path)
+load_sample(LV2_Log_Logger* logger, const char* path, const int sample_rate)
 {
   lv2_log_trace(logger, "Loading %s\n", path);
 
@@ -155,6 +157,42 @@ load_sample(LV2_Log_Logger* logger, const char* path)
     info->channels = 1;
   }
 
+  if (info->samplerate != sample_rate) {
+    lv2_log_trace(logger,
+                  "Converting from %d Hz to %d Hz\n",
+                  info->samplerate,
+                  sample_rate);
+
+    const double src_ratio     = (double)sample_rate / (double)info->samplerate;
+    const double output_length = ceil((double)info->frames * src_ratio);
+    const long   output_frames = (long)output_length;
+    float* const output_buffer = (float*)malloc(sizeof(float) * output_frames);
+
+    SRC_DATA src_data = {
+      data,
+      output_buffer,
+      info->frames,
+      output_frames,
+      0,
+      0,
+      0,
+      src_ratio,
+    };
+
+    if (src_simple(&src_data, SRC_SINC_BEST_QUALITY, 1) != 0) {
+      lv2_log_error(logger, "Sample rate conversion failed\n");
+      free(output_buffer);
+    } else {
+      // Replace original data with converted buffer
+      free(data);
+      data         = output_buffer;
+      info->frames = src_data.output_frames_gen;
+    }
+  } else {
+    lv2_log_trace(
+      logger, "Sample matches the current rate of %d Hz\n", sample_rate);
+  }
+
   // Fill sample struct and return it
   sample->data     = data;
   sample->path     = (char*)malloc(path_len + 1);
@@ -205,7 +243,7 @@ work(LV2_Handle                  instance,
     }
 
     // Load sample.
-    Sample* sample = load_sample(&self->logger, path);
+    Sample* sample = load_sample(&self->logger, path, self->sample_rate);
     if (sample) {
       // Send new sample to run() to be applied
       respond(handle, sizeof(Sample*), &sample);
@@ -301,8 +339,9 @@ instantiate(const LV2_Descriptor*     descriptor,
   lv2_atom_forge_init(&self->forge, self->map);
   peaks_sender_init(&self->psend, self->map);
 
-  self->gain    = 1.0f;
-  self->gain_dB = 0.0f;
+  self->gain        = 1.0f;
+  self->gain_dB     = 0.0f;
+  self->sample_rate = (int)rate;
 
   return (LV2_Handle)self;
 }
@@ -594,7 +633,7 @@ restore(LV2_Handle                  instance,
   if (!self->activated || !schedule) {
     // No scheduling available, load sample immediately
     lv2_log_trace(&self->logger, "Synchronous restore\n");
-    Sample* sample = load_sample(&self->logger, path);
+    Sample* sample = load_sample(&self->logger, path, self->sample_rate);
     if (sample) {
       free_sample(self, self->sample);
       self->sample         = sample;
-- 
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