From b0e2fc1a4724ed153d3ffebb04e67faff50766d5 Mon Sep 17 00:00:00 2001
From: falkTX <falktx@falktx.com>
Date: Mon, 15 Mar 2021 11:09:48 +0000
Subject: [PATCH] eg-sampler: add resampling via libsamplerate

---
 plugins/eg-sampler.lv2/sampler.c | 36 +++++++++++++++++++++++++++++---
 plugins/eg-sampler.lv2/wscript   |  1 +
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/plugins/eg-sampler.lv2/sampler.c b/plugins/eg-sampler.lv2/sampler.c
index 9675003d..21a28c8d 100644
--- a/plugins/eg-sampler.lv2/sampler.c
+++ b/plugins/eg-sampler.lv2/sampler.c
@@ -34,6 +34,7 @@
 #include "lv2/worker/worker.h"
 
 #include <sndfile.h>
+#include <samplerate.h>
 
 #include <math.h>
 #include <stdbool.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, int sample_rate)
 {
   lv2_log_trace(logger, "Loading %s\n", path);
 
@@ -154,6 +156,33 @@ load_sample(LV2_Log_Logger* logger, const char* path)
     info->channels = 1;
   }
 
+  if (info->samplerate != sample_rate) {
+    lv2_log_trace(logger, "Converting sample rate..\n");
+
+    const double src_ratio = (double)sample_rate/(double)info->samplerate;
+    const int output_size = ceil(info->frames * src_ratio);
+    float* const output_buffer = malloc(sizeof(float) * output_size);
+
+    SRC_DATA src_data;
+    src_data.data_in = data;
+    src_data.data_out = output_buffer;
+    src_data.input_frames = info->frames;
+    src_data.output_frames = output_size;
+    src_data.src_ratio = src_ratio;
+
+    if (src_simple(&src_data, SRC_SINC_BEST_QUALITY, 1) != 0) {
+      lv2_log_error(logger, "Sample rate conversion failed, eg-sampler will use unconverted sample\n");
+      free(output_buffer);
+    } else {
+      // set new amount of frames
+      info->frames = src_data.output_frames_gen;
+      // swap buffers
+      free(data);
+      data = output_buffer;
+      lv2_log_trace(logger, "Conversion finished\n");
+    }
+  }
+
   // Fill sample struct and return it
   sample->data     = data;
   sample->path     = (char*)malloc(path_len + 1);
@@ -204,7 +233,7 @@ 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);
@@ -298,6 +327,7 @@ instantiate(const LV2_Descriptor*     descriptor,
 
   self->gain    = 1.0f;
   self->gain_dB = 0.0f;
+  self->sample_rate = (int)rate;
 
   return (LV2_Handle)self;
 }
@@ -585,7 +615,7 @@ 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;
diff --git a/plugins/eg-sampler.lv2/wscript b/plugins/eg-sampler.lv2/wscript
index 8c640c10..4d9debc6 100644
--- a/plugins/eg-sampler.lv2/wscript
+++ b/plugins/eg-sampler.lv2/wscript
@@ -22,6 +22,7 @@ def configure(conf):
 
     conf.check_pkg('lv2 >= 1.2.1', uselib_store='LV2')
     conf.check_pkg('sndfile >= 1.0.0', uselib_store='SNDFILE')
+    conf.check_pkg('samplerate >= 0.1.0', uselib_store='SAMPLERATE')
     conf.check_pkg('gtk+-2.0 >= 2.18.0',
                    uselib_store='GTK2',
                    system=True,