1 files changed, 144 insertions, 0 deletions
diff --git a/src/tangara/audio/audio_decoder.cpp b/src/tangara/audio/audio_decoder.cpp
new file mode 100644
index 00000000..bf2d3fbe
--- /dev/null
+++ b/src/tangara/audio/audio_decoder.cpp
@@ -0,0 +1,144 @@
+/*
+ * Copyright 2023 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "audio_decoder.hpp"
+
+#include <algorithm>
+#include <cmath>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <deque>
+#include <memory>
+#include <span>
+#include <variant>
+
+#include "esp_err.h"
+#include "esp_heap_caps.h"
+#include "esp_log.h"
+#include "freertos/portmacro.h"
+#include "freertos/projdefs.h"
+#include "freertos/queue.h"
+#include "freertos/ringbuf.h"
+
+#include "audio_converter.hpp"
+#include "audio_events.hpp"
+#include "audio_fsm.hpp"
+#include "audio_sink.hpp"
+#include "audio_source.hpp"
+#include "codec.hpp"
+#include "event_queue.hpp"
+#include "fatfs_audio_input.hpp"
+#include "i2s_dac.hpp"
+#include "sample.hpp"
+#include "tasks.hpp"
+#include "track.hpp"
+#include "types.hpp"
+#include "ui_fsm.hpp"
+
+namespace audio {
+
+[[maybe_unused]] static const char* kTag = "audio_dec";
+
+static constexpr std::size_t kCodecBufferLength =
+    drivers::kI2SBufferLengthFrames * sizeof(sample::Sample);
+
+auto Decoder::Start(std::shared_ptr<IAudioSource> source,
+                    std::shared_ptr<SampleConverter> sink) -> Decoder* {
+  Decoder* task = new Decoder(source, sink);
+  tasks::StartPersistent<tasks::Type::kAudioDecoder>([=]() { task->Main(); });
+  return task;
+}
+
+Decoder::Decoder(std::shared_ptr<IAudioSource> source,
+                 std::shared_ptr<SampleConverter> mixer)
+    : source_(source), converter_(mixer), codec_(), current_format_() {
+  ESP_LOGI(kTag, "allocating codec buffer, %u KiB", kCodecBufferLength / 1024);
+  codec_buffer_ = {
+      reinterpret_cast<sample::Sample*>(heap_caps_calloc(
+          kCodecBufferLength, sizeof(sample::Sample), MALLOC_CAP_DMA)),
+      kCodecBufferLength};
+}
+
+void Decoder::Main() {
+  for (;;) {
+    if (source_->HasNewStream() || !stream_) {
+      std::shared_ptr<TaggedStream> new_stream = source_->NextStream();
+      if (new_stream && BeginDecoding(new_stream)) {
+        stream_ = new_stream;
+      } else {
+        continue;
+      }
+    }
+
+    if (ContinueDecoding()) {
+      stream_.reset();
+    }
+  }
+}
+
+auto Decoder::BeginDecoding(std::shared_ptr<TaggedStream> stream) -> bool {
+  // Ensure any previous codec is freed before creating a new one.
+  codec_.reset();
+  codec_.reset(codecs::CreateCodecForType(stream->type()).value_or(nullptr));
+  if (!codec_) {
+    ESP_LOGE(kTag, "no codec found for stream");
+    return false;
+  }
+
+  auto open_res = codec_->OpenStream(stream, stream->Offset());
+  if (open_res.has_error()) {
+    ESP_LOGE(kTag, "codec failed to start: %s",
+             codecs::ICodec::ErrorString(open_res.error()).c_str());
+    return false;
+  }
+  stream->SetPreambleFinished();
+  current_sink_format_ = IAudioOutput::Format{
+      .sample_rate = open_res->sample_rate_hz,
+      .num_channels = open_res->num_channels,
+      .bits_per_sample = 16,
+  };
+
+  std::optional<uint32_t> duration;
+  if (open_res->total_samples) {
+    duration = open_res->total_samples.value() / open_res->num_channels /
+               open_res->sample_rate_hz;
+  }
+
+  converter_->beginStream(std::make_shared<TrackInfo>(TrackInfo{
+      .tags = stream->tags(),
+      .uri = stream->Filepath(),
+      .duration = duration,
+      .start_offset = stream->Offset(),
+      .bitrate_kbps = open_res->sample_rate_hz,
+      .encoding = stream->type(),
+      .format = *current_sink_format_,
+  }));
+
+  return true;
+}
+
+auto Decoder::ContinueDecoding() -> bool {
+  auto res = codec_->DecodeTo(codec_buffer_);
+  if (res.has_error()) {
+    converter_->endStream();
+    return true;
+  }
+
+  if (res->samples_written > 0) {
+    converter_->continueStream(codec_buffer_.first(res->samples_written));
+  }
+
+  if (res->is_stream_finished) {
+    converter_->endStream();
+    codec_.reset();
+  }
+
+  return res->is_stream_finished;
+}
+
+}  // namespace audio