1 files changed, 55 insertions, 0 deletions
diff --git a/src/tangara/audio/resample.cpp b/src/tangara/audio/resample.cpp
new file mode 100644
index 00000000..143ce230
--- /dev/null
+++ b/src/tangara/audio/resample.cpp
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2023 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+#include "audio/resample.hpp"
+
+#include <algorithm>
+#include <cmath>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <numeric>
+
+#include "esp_log.h"
+#include "speex/speex_resampler.h"
+
+#include "sample.hpp"
+
+namespace audio {
+
+static constexpr int kQuality = SPEEX_RESAMPLER_QUALITY_MIN;
+
+Resampler::Resampler(uint32_t source_sample_rate,
+                     uint32_t target_sample_rate,
+                     uint8_t num_channels)
+    : err_(0),
+      resampler_(speex_resampler_init(num_channels,
+                                      source_sample_rate,
+                                      target_sample_rate,
+                                      kQuality,
+                                      &err_)),
+      num_channels_(num_channels) {
+  assert(err_ == 0);
+}
+
+Resampler::~Resampler() {
+  speex_resampler_destroy(resampler_);
+}
+
+auto Resampler::Process(std::span<sample::Sample> input,
+                        std::span<sample::Sample> output,
+                        bool end_of_data) -> std::pair<size_t, size_t> {
+  uint32_t samples_used = input.size() / num_channels_;
+  uint32_t samples_produced = output.size() / num_channels_;
+
+  int err = speex_resampler_process_interleaved_int(
+      resampler_, input.data(), &samples_used, output.data(),
+      &samples_produced);
+  assert(err == 0);
+
+  return {samples_used * num_channels_, samples_produced * num_channels_};
+}
+
+}  // namespace audio