fix build errors

24 files changed, 560 insertions, 506 deletions

diff --git a/src/audio/CMakeLists.txt b/src/audio/CMakeLists.txt
index e3f7dd33..32ca1a56 100644
--- a/src/audio/CMakeLists.txt
+++ b/src/audio/CMakeLists.txt
@@ -2,6 +2,6 @@ idf_component_register(
   SRCS "audio_decoder.cpp" "audio_task.cpp" "chunk.cpp" "fatfs_audio_input.cpp"
   "stream_info.cpp"
   INCLUDE_DIRS "include"
-  REQUIRES "codecs" "drivers" "cbor" "result" "tasks")
+  REQUIRES "codecs" "drivers" "cbor_wrapper" "result" "tasks")
 
 target_compile_options(${COMPONENT_LIB} PRIVATE ${EXTRA_WARNINGS})
diff --git a/src/audio/audio_decoder.cpp b/src/audio/audio_decoder.cpp
index 02217187..a19fd5bf 100644
--- a/src/audio/audio_decoder.cpp
+++ b/src/audio/audio_decoder.cpp
@@ -1,29 +1,41 @@
 #include "audio_decoder.hpp"
+
 #include <string.h>
+
 #include <cstddef>
 #include <cstdint>
-#include "chunk.hpp"
+
+#include "freertos/FreeRTOS.h"
+
 #include "esp_heap_caps.h"
+#include "freertos/message_buffer.h"
 #include "freertos/portmacro.h"
-#include "include/audio_element.hpp"
-#include "include/fatfs_audio_input.hpp"
+
+#include "audio_element.hpp"
+#include "chunk.hpp"
+#include "fatfs_audio_input.hpp"
+
+static const char* kTag = "DEC";
 
 namespace audio {
 
 AudioDecoder::AudioDecoder()
     : IAudioElement(),
-      chunk_buffer_(heap_caps_malloc(kMaxChunkSize, MALLOC_CAP_SPIRAM)),
-      stream_info_({}) {}
+      stream_info_({}),
+      chunk_buffer_(static_cast<uint8_t*>(
+          heap_caps_malloc(kMaxChunkSize, MALLOC_CAP_SPIRAM)))
+
+{}
 
 AudioDecoder::~AudioDecoder() {
   free(chunk_buffer_);
 }
 
-auto AudioDecoder::SetInputBuffer(StreamBufferHandle_t* buffer) -> void {
+auto AudioDecoder::SetInputBuffer(MessageBufferHandle_t* buffer) -> void {
   input_buffer_ = buffer;
 }
 
-auto AudioDecoder::SetOutputBuffer(StreamBufferHandle_t* buffer) -> void {
+auto AudioDecoder::SetOutputBuffer(MessageBufferHandle_t* buffer) -> void {
   output_buffer_ = buffer;
 }
 
@@ -34,12 +46,12 @@ auto AudioDecoder::ProcessStreamInfo(StreamInfo&& info)
   // Reuse the existing codec if we can. This will help with gapless playback,
   // since we can potentially just continue to decode as we were before,
   // without any setup overhead.
-  if (current_codec_->CanHandleFile(info.path)) {
+  if (current_codec_->CanHandleFile(info.Path().value_or(""))) {
     current_codec_->ResetForNewStream();
     return {};
   }
 
-  auto result = codecs::CreateCodecForFile(info.path);
+  auto result = codecs::CreateCodecForFile(info.Path().value());
   if (result.has_value()) {
     current_codec_ = std::move(result.value());
   } else {
@@ -57,26 +69,46 @@ auto AudioDecoder::ProcessChunk(uint8_t* data, std::size_t length)
   }
 
   current_codec_->SetInput(data, length);
-  cpp::result<size_t, codecs::ICodec::ProcessingError> result;
+
+  bool has_samples_to_send = false;
+  bool needs_more_input = false;
+  std::optional<codecs::ICodec::ProcessingError> error = std::nullopt;
   WriteChunksToStream(
-      output_buffer_, working_buffer_, kWorkingBufferSize,
-      [&](uint8_t* buf, size_t len) {
-        result = current_codec_->Process(data, length, buf, len);
-        if (result.has_error()) {
-          // End our output stream immediately if the codec barfed.
-          return 0;
+      output_buffer_, chunk_buffer_, kMaxChunkSize,
+      [&](uint8_t* buf, size_t len) -> std::size_t {
+        std::size_t bytes_written = 0;
+        // Continue filling up the output buffer so long as we have samples
+        // leftover, or are able to synthesize more samples from the input.
+        while (has_samples_to_send || !needs_more_input) {
+          if (!has_samples_to_send) {
+            auto result = current_codec_->ProcessNextFrame();
+            has_samples_to_send = true;
+            if (result.has_error()) {
+              error = result.error();
+              // End our output stream immediately if the codec barfed.
+              return 0;
+            } else {
+              needs_more_input = result.value();
+            }
+          } else {
+            auto result = current_codec_->WriteOutputSamples(
+                buf + bytes_written, len - bytes_written);
+            bytes_written += result.first;
+            has_samples_to_send = !result.second;
+          }
         }
-        return result.value();
+        return bytes_written;
       },
       // This element doesn't support any kind of out of band commands, so we
       // can just suspend the whole task if the output buffer fills up.
       portMAX_DELAY);
 
-  if (result.has_error()) {
+  if (error) {
+    ESP_LOGE(kTag, "Codec encountered error %d", error.value());
     return cpp::fail(IO_ERROR);
   }
 
-  return current_codec_->GetOutputProcessed();
+  return current_codec_->GetInputPosition();
 }
 
 auto AudioDecoder::ProcessIdle() -> cpp::result<void, StreamError> {
diff --git a/src/audio/audio_task.cpp b/src/audio/audio_task.cpp
index a125548a..f3362897 100644
--- a/src/audio/audio_task.cpp
+++ b/src/audio/audio_task.cpp
@@ -13,7 +13,7 @@
 #include "freertos/stream_buffer.h"
 
 #include "audio_element.hpp"
-#include "include/audio_element.hpp"
+#include "chunk.hpp"
 #include "stream_message.hpp"
 #include "tasks.hpp"
 
@@ -25,72 +25,83 @@ static const size_t kChunkBufferSize = kMaxChunkSize * 1.5;
 
 auto StartAudioTask(const std::string& name,
                     std::shared_ptr<IAudioElement>& element) -> void {
-  AudioTaskArgs* args = new AudioTaskArgs(element);
+  AudioTaskArgs* args = new AudioTaskArgs{.element = element};
   xTaskCreate(&AudioTaskMain, name.c_str(), element->StackSizeBytes(), args,
               kTaskPriorityAudio, NULL);
 }
 
 void AudioTaskMain(void* args) {
-  AudioTaskArgs* real_args = reinterpret_cast<AudioTaskArgs*>(args);
-  std::shared_ptr<IAudioElement> element = std::move(real_args->element);
-  delete real_args;
-
-  ChunkReader chunk_reader = ChunkReader(element->InputBuffer());
-
-  while (1) {
-    cpp::result<size_t, IAudioElement::StreamError> process_res;
-
-    // If this element has an input stream, then our top priority is processing
-    // any chunks from it. Try doing this first, then fall back to the other
-    // cases.
-    bool has_received_message = false;
-    if (stream != nullptr) {
-      EncodeReadResult chunk_res = chunk_reader.ReadChunkFromStream(
-          [&](uint8_t* data, std::size_t length) -> std::optional<size_t> {
-            process_res = element->ProcessChunk(data, length);
-            if (process_res.has_value()) {
-              return process_res.value();
-            } else {
-              return {};
-            }
-          },
-          element->IdleTimeout());
-
-      if (chunk_res == CHUNK_PROCESSING_ERROR ||
-          chunk_res == CHUNK_DECODING_ERROR) {
-        break;  // TODO.
-      } else if (chunk_res == CHUNK_STREAM_ENDED) {
-        has_received_message = true;
+  {
+    AudioTaskArgs* real_args = reinterpret_cast<AudioTaskArgs*>(args);
+    std::shared_ptr<IAudioElement> element = std::move(real_args->element);
+    delete real_args;
+
+    ChunkReader chunk_reader = ChunkReader(element->InputBuffer());
+
+    while (1) {
+      cpp::result<size_t, StreamError> process_res;
+
+      // If this element has an input stream, then our top priority is
+      // processing any chunks from it. Try doing this first, then fall back to
+      // the other cases.
+      bool has_received_message = false;
+      if (element->InputBuffer() != nullptr) {
+        ChunkReadResult chunk_res = chunk_reader.ReadChunkFromStream(
+            [&](uint8_t* data, std::size_t length) -> std::optional<size_t> {
+              process_res = element->ProcessChunk(data, length);
+              if (process_res.has_value()) {
+                return process_res.value();
+              } else {
+                return {};
+              }
+            },
+            element->IdleTimeout());
+
+        if (chunk_res == CHUNK_PROCESSING_ERROR ||
+            chunk_res == CHUNK_DECODING_ERROR) {
+          break;  // TODO.
+        } else if (chunk_res == CHUNK_STREAM_ENDED) {
+          has_received_message = true;
+        }
       }
-    }
 
-    if (has_received_message) {
-      auto& [buffer, length] = chunk_reader.GetLastMessage();
-      auto decoder_res = cbor::ArrayDecoder::Create(buffer, length);
-      if (decoder_res.has_error()) {
-        // TODO.
-        break;
-      }
-      auto decoder = decoder_res.value();
-      MessageType message_type = decoder->NextValue();
-      if (message_type == TYPE_STREAM_INFO) {
-        element->ProcessStreamInfo(StreamInfo(decoder->Iterator()););
+      if (has_received_message) {
+        auto [buffer, length] = chunk_reader.GetLastMessage();
+        auto decoder_res = cbor::ArrayDecoder::Create(buffer, length);
+        if (decoder_res.has_error()) {
+          // TODO.
+          break;
+        }
+        auto decoder = std::move(decoder_res.value());
+        // TODO: this can be more elegant i think
+        cpp::result<uint64_t, CborError> message_type =
+            decoder->NextValue<uint64_t>();
+        if (message_type.has_error()) {
+          break;  // TODO.
+        } else if (message_type.value() == TYPE_STREAM_INFO) {
+          auto info_decoder = cbor::MapDecoder::Create(decoder->Iterator());
+          if (info_decoder.has_value()) {
+            auto process_error = element->ProcessStreamInfo(
+                StreamInfo(info_decoder.value().get()));
+            if (process_error.has_error()) {
+              break;  // TODO.
+            }
+          } else {
+            break;  // TODO.
+          }
+        }
       }
-    }
 
-    // TODO: Do any out of band reading, such a a pause command, here.
+      // TODO: Do any out of band reading, such a a pause command, here.
 
-    // Chunk reading must have timed out, or we don't have an input stream.
-    // Signal the element to do any of its idle tasks.
-    process_res = element->ProcessIdle();
-    if (process_res.has_error()) {
-      break;  // TODO.
+      // Chunk reading must have timed out, or we don't have an input stream.
+      // Signal the element to do any of its idle tasks.
+      auto process_error = element->ProcessIdle();
+      if (process_error.has_error()) {
+        break;  // TODO.
+      }
     }
   }
-
-  element.clear();
-  free(chunk_buffer_);
-
   vTaskDelete(NULL);
 }
 
diff --git a/src/audio/chunk.cpp b/src/audio/chunk.cpp
index a157b946..718b2649 100644
--- a/src/audio/chunk.cpp
+++ b/src/audio/chunk.cpp
@@ -1,17 +1,20 @@
 #include "chunk.hpp"
 
 #include <string.h>
+
 #include <cstddef>
 #include <cstdint>
+
+#include "cbor.h"
+
 #include "cbor_decoder.hpp"
 #include "cbor_encoder.hpp"
-#include "esp-idf/components/cbor/tinycbor/src/cbor.h"
 #include "stream_message.hpp"
 
 namespace audio {
 
 // TODO: tune.
-static const std::size_t kMaxChunkSize = 512;
+const std::size_t kMaxChunkSize = 512;
 
 // TODO: tune
 static const std::size_t kWorkingBufferSize = kMaxChunkSize * 1.5;
@@ -28,7 +31,7 @@ auto WriteChunksToStream(MessageBufferHandle_t* stream,
                          uint8_t* working_buffer,
                          size_t working_buffer_length,
                          std::function<size_t(uint8_t*, size_t)> callback,
-                         TickType_t max_wait) -> EncodeWriteResult {
+                         TickType_t max_wait) -> ChunkWriteResult {
   size_t header_size = kInitialHeaderSize;
   while (1) {
     // First, ask the callback for some data to write.
@@ -43,9 +46,9 @@ auto WriteChunksToStream(MessageBufferHandle_t* stream,
     // Put together a header.
     cbor::Encoder encoder(cbor::CONTAINER_ARRAY, 3, working_buffer,
                           working_buffer_length);
-    encoder.WriteUnsigned(TYPE_CHUNK_HEADER);
-    encoder.WriteUnsigned(header_size);
-    encoder.WriteUnsigned(chunk_size);
+    encoder.WriteValue(TYPE_CHUNK_HEADER);
+    encoder.WriteValue(header_size);
+    encoder.WriteValue(chunk_size);
 
     size_t new_header_size = header_size;
     cpp::result<size_t, CborError> encoder_res = encoder.Finish();
@@ -76,7 +79,8 @@ auto WriteChunksToStream(MessageBufferHandle_t* stream,
 }
 
 ChunkReader::ChunkReader(MessageBufferHandle_t* stream) : stream_(stream) {
-  working_buffer_ = heap_caps_malloc(kWorkingBufferSize, MALLOC_CAP_SPIRAM);
+  working_buffer_ = static_cast<uint8_t*>(
+      heap_caps_malloc(kWorkingBufferSize, MALLOC_CAP_SPIRAM));
 };
 
 ChunkReader::~ChunkReader() {
@@ -94,7 +98,7 @@ auto ChunkReader::GetLastMessage() -> std::pair<uint8_t*, size_t> {
 
 auto ChunkReader::ReadChunkFromStream(
     std::function<std::optional<size_t>(uint8_t*, size_t)> callback,
-    TickType_t max_wait) -> EncodeReadResult {
+    TickType_t max_wait) -> ChunkReadResult {
   // First, wait for a message to arrive over the buffer.
   last_message_size_ =
       xMessageBufferReceive(*stream_, working_buffer_ + leftover_bytes_,
@@ -104,14 +108,15 @@ auto ChunkReader::ReadChunkFromStream(
     return CHUNK_READ_TIMEOUT;
   }
 
-  auto decoder = cbor::MapDecoder::Create(working_buffer_ + leftover_bytes_,
-                                          last_message_size_);
+  auto decoder = cbor::ArrayDecoder::Create(working_buffer_ + leftover_bytes_,
+                                            last_message_size_);
   if (decoder.has_error()) {
     // Weird; this implies someone is shoving invalid data into the buffer.
     return CHUNK_DECODING_ERROR;
   }
 
-  MessageType type = decoder.value().ParseUnsigned().value_or(TYPE_UNKNOWN);
+  MessageType type = static_cast<MessageType>(
+      decoder.value()->NextValue<uint64_t>().value_or(TYPE_UNKNOWN));
   if (type != TYPE_CHUNK_HEADER) {
     // This message wasn't for us, so let the caller handle it.
     Reset();
@@ -119,9 +124,9 @@ auto ChunkReader::ReadChunkFromStream(
   }
 
   // Work the size and position of the chunk.
-  header_length = decoder.ParseUnsigned().value_or(0);
-  chunk_length = decoder.ParseUnsigned().value_or(0);
-  if (decoder.Failed()) {
+  size_t header_length = decoder.value()->NextValue<uint64_t>().value_or(0);
+  size_t chunk_length = decoder.value()->NextValue<uint64_t>().value_or(0);
+  if (decoder.value()->Failed()) {
     return CHUNK_DECODING_ERROR;
   }
 
@@ -146,7 +151,10 @@ auto ChunkReader::ReadChunkFromStream(
   if (leftover_bytes_ > 0) {
     memmove(working_buffer_, combined_buffer + amount_processed.value(),
             leftover_bytes_);
+    return CHUNK_LEFTOVER_DATA;
   }
+
+  return CHUNK_READ_OKAY;
 }
 
 }  // namespace audio
diff --git a/src/audio/fatfs_audio_input.cpp b/src/audio/fatfs_audio_input.cpp
index 351fd017..dee090d0 100644
--- a/src/audio/fatfs_audio_input.cpp
+++ b/src/audio/fatfs_audio_input.cpp
@@ -1,14 +1,15 @@
-#include "fatfs_audio_input.hpp<D-c>ccc
+#include "fatfs_audio_input.hpp"
+
 #include <cstdint>
 #include <memory>
-#include "chunk.hpp"
-#include "fatfs_audio_input.hpp"
+#include <string>
 
+#include "audio_element.hpp"
 #include "esp_heap_caps.h"
+#include "freertos/portmacro.h"
 
 #include "audio_element.hpp"
-#include "freertos/portmacro.h"
-#include "include/audio_element.hpp"
+#include "chunk.hpp"
 
 namespace audio {
 
@@ -20,14 +21,17 @@ static const std::size_t kOutputBufferSize = 1024 * 4;
 
 FatfsAudioInput::FatfsAudioInput(std::shared_ptr<drivers::SdStorage> storage)
     : IAudioElement(), storage_(storage) {
-  file_buffer_ = heap_caps_malloc(kMaxFrameSize, MALLOC_CAP_SPIRAM);
+  file_buffer_ = static_cast<uint8_t*>(
+      heap_caps_malloc(kFileBufferSize, MALLOC_CAP_SPIRAM));
   file_buffer_read_pos_ = file_buffer_;
   file_buffer_write_pos_ = file_buffer_;
-  chunk_buffer_ = heap_caps_malloc(kMaxChunkSize, MALLOC_CAP_SPIRAM);
+  chunk_buffer_ =
+      static_cast<uint8_t*>(heap_caps_malloc(kMaxChunkSize, MALLOC_CAP_SPIRAM));
 
-  output_buffer_memory_ =
-      heap_caps_malloc(kOutputBufferSize, MALLOC_CAP_SPIRAM);
-  output_buffer_ = xMessageBufferCreateStatic(
+  output_buffer_memory_ = static_cast<uint8_t*>(
+      heap_caps_malloc(kOutputBufferSize, MALLOC_CAP_SPIRAM));
+  output_buffer_ = new MessageBufferHandle_t;
+  *output_buffer_ = xMessageBufferCreateStatic(
       kOutputBufferSize, output_buffer_memory_, &output_buffer_metadata_);
 }
 
@@ -36,24 +40,18 @@ FatfsAudioInput::~FatfsAudioInput() {
   free(chunk_buffer_);
   vMessageBufferDelete(output_buffer_);
   free(output_buffer_memory_);
+  free(output_buffer_);
 }
 
-auto FatfsAudioInput::InputBuffer() -> MessageBufferHandle_t {
-  return input_buffer_;
-}
-
-auto FatfsAudioInput::OutputBuffer() -> MessageBufferHandle_t {
-  return output_buffer_;
-}
-
-auto FatfsAudioInput::ProcessStreamInfo(StreamInfo& info)
+auto FatfsAudioInput::ProcessStreamInfo(StreamInfo&& info)
     -> cpp::result<void, StreamError> {
   if (is_file_open_) {
     f_close(&current_file_);
     is_file_open_ = false;
   }
 
-  FRESULT res = f_open(&current_file_, info.path.c_str(), FA_READ);
+  std::string path = info.Path().value_or("");
+  FRESULT res = f_open(&current_file_, path.c_str(), FA_READ);
   if (res != FR_OK) {
     return cpp::fail(IO_ERROR);
   }
@@ -66,12 +64,12 @@ auto FatfsAudioInput::ProcessStreamInfo(StreamInfo& info)
 }
 
 auto FatfsAudioInput::ProcessChunk(uint8_t* data, std::size_t length)
-    -> cpp::result<void, StreamError> {
+    -> cpp::result<size_t, StreamError> {
   // TODO.
-  return {};
+  return 0;
 }
 
-static auto GetRingBufferDistance() -> size_t {
+auto FatfsAudioInput::GetRingBufferDistance() -> size_t {
   if (file_buffer_read_pos_ == file_buffer_write_pos_) {
     return 0;
   }
@@ -82,10 +80,10 @@ static auto GetRingBufferDistance() -> size_t {
       // Read position to end of buffer.
       (file_buffer_ + kFileBufferSize - file_buffer_read_pos_)
       // Start of buffer to write position.
-      + (file_buffer_write_pos_ - file_buffer_)
+      + (file_buffer_write_pos_ - file_buffer_);
 }
 
-virtual auto FatfsAudioInput::ProcessIdle() -> cpp::result<void, StreamError> {
+auto FatfsAudioInput::ProcessIdle() -> cpp::result<void, StreamError> {
   // First, see if we're able to fill up the input buffer with any more of the
   // file's contents.
   if (is_file_open_) {
@@ -103,8 +101,8 @@ virtual auto FatfsAudioInput::ProcessIdle() -> cpp::result<void, StreamError> {
       UINT bytes_read = 0;
       FRESULT result = f_read(&current_file_, file_buffer_write_pos_, read_size,
                               &bytes_read);
-      if (!FR_OK) {
-        return ERROR;  // TODO;
+      if (result != FR_OK) {
+        return cpp::fail(IO_ERROR);  // TODO;
       }
 
       if (f_eof(&current_file_)) {
@@ -123,16 +121,16 @@ virtual auto FatfsAudioInput::ProcessIdle() -> cpp::result<void, StreamError> {
 
   // Now stream data into the output buffer until it's full.
   pending_read_pos_ = nullptr;
-  EncodeWriteResult result =
-      WriteChunksToStream(&output_buffer_, chunk_buffer_, kMaxChunkSize,
-                          &SendChunk, kServiceInterval);
+  ChunkWriteResult result = WriteChunksToStream(
+      output_buffer_, chunk_buffer_, kMaxChunkSize,
+      [&](uint8_t* b, size_t s) { return SendChunk(b, s); }, kServiceInterval);
 
   switch (result) {
     case CHUNK_WRITE_TIMEOUT:
     case CHUNK_OUT_OF_DATA:
-      return;  // TODO.
+      return {};  // TODO.
     default:
-      return;  // TODO.
+      return {};  // TODO.
   }
 }
 
diff --git a/src/audio/include/audio_decoder.hpp b/src/audio/include/audio_decoder.hpp
index 98ebdc71..a4508c3e 100644
--- a/src/audio/include/audio_decoder.hpp
+++ b/src/audio/include/audio_decoder.hpp
@@ -18,8 +18,13 @@ class AudioDecoder : public IAudioElement {
   AudioDecoder();
   ~AudioDecoder();
 
-  auto SetInputBuffer(StreamBufferHandle_t*) -> void;
-  auto SetOutputBuffer(StreamBufferHandle_t*) -> void;
+  auto SetInputBuffer(MessageBufferHandle_t*) -> void;
+  auto SetOutputBuffer(MessageBufferHandle_t*) -> void;
+
+  auto ProcessStreamInfo(StreamInfo&& info) -> cpp::result<void, StreamError>;
+  auto ProcessChunk(uint8_t* data, std::size_t length)
+      -> cpp::result<size_t, StreamError>;
+  auto ProcessIdle() -> cpp::result<void, StreamError>;
 
   AudioDecoder(const AudioDecoder&) = delete;
   AudioDecoder& operator=(const AudioDecoder&) = delete;
diff --git a/src/audio/include/audio_element.hpp b/src/audio/include/audio_element.hpp
index 2a2f0727..13a48590 100644
--- a/src/audio/include/audio_element.hpp
+++ b/src/audio/include/audio_element.hpp
@@ -1,13 +1,28 @@
 #pragma once
 
 #include <stdint.h>
+
 #include <cstdint>
+
+#include "freertos/FreeRTOS.h"
+
+#include "freertos/message_buffer.h"
 #include "freertos/portmacro.h"
 #include "result.hpp"
+
+#include "stream_info.hpp"
 #include "types.hpp"
 
 namespace audio {
 
+/* Errors that may be returned by any of the Process* methods. */
+enum StreamError {
+  // Indicates that this element is unable to handle the upcoming chunks.
+  UNSUPPORTED_STREAM,
+  // Indicates an error with reading or writing stream data.
+  IO_ERROR,
+};
+
 /*
  * One indepedentent part of an audio pipeline. Each element has an input and
  * output message stream, and is responsible for taking data from the input
@@ -46,14 +61,6 @@ class IAudioElement {
   /* Returns this element's output buffer. */
   auto OutputBuffer() -> MessageBufferHandle_t* { return output_buffer_; }
 
-  /* Errors that may be returned by any of the Process* methods. */
-  enum StreamError {
-    // Indicates that this element is unable to handle the upcoming chunks.
-    UNSUPPORTED_STREAM,
-    // Indicates an error with reading or writing stream data.
-    IO_ERROR,
-  };
-
   /*
    * Called when a StreamInfo message is received. Used to configure this
    * element in preperation for incoming chunks.
@@ -78,8 +85,8 @@ class IAudioElement {
   virtual auto ProcessIdle() -> cpp::result<void, StreamError> = 0;
 
  protected:
-  StreamBufferHandle_t* input_buffer_;
-  StreamBufferHandle_t* output_buffer_;
+  MessageBufferHandle_t* input_buffer_;
+  MessageBufferHandle_t* output_buffer_;
 };
 
 }  // namespace audio
diff --git a/src/audio/include/chunk.hpp b/src/audio/include/chunk.hpp
index a3f943ea..365c83d0 100644
--- a/src/audio/include/chunk.hpp
+++ b/src/audio/include/chunk.hpp
@@ -4,8 +4,13 @@
 #include <cstdint>
 #include <optional>
 #include <string>
-#include "esp-idf/components/cbor/tinycbor/src/cbor.h"
+
+#include "freertos/FreeRTOS.h"
+
+#include "cbor.h"
+#include "freertos/message_buffer.h"
 #include "freertos/portmacro.h"
+#include "freertos/queue.h"
 #include "result.hpp"
 
 namespace audio {
@@ -35,7 +40,22 @@ auto WriteChunksToStream(MessageBufferHandle_t* stream,
                          uint8_t* working_buffer,
                          size_t working_buffer_length,
                          std::function<size_t(uint8_t*, size_t)> callback,
-                         TickType_t max_wait) -> EncodeWriteResult;
+                         TickType_t max_wait) -> ChunkWriteResult;
+
+enum ChunkReadResult {
+  CHUNK_READ_OKAY,
+  // Returned when the chunk was read successfully, but the consumer did not
+  // use all of the data.
+  CHUNK_LEFTOVER_DATA,
+  // Returned an error in parsing the cbor-encoded header.
+  CHUNK_DECODING_ERROR,
+  // Returned when max_wait expired before any data was read.
+  CHUNK_READ_TIMEOUT,
+  // Returned when a non-chunk message is received.
+  CHUNK_STREAM_ENDED,
+  // Returned when the processing callback does not return a value.
+  CHUNK_PROCESSING_ERROR,
+};
 
 class ChunkReader {
  public:
@@ -46,17 +66,6 @@ class ChunkReader {
 
   auto GetLastMessage() -> std::pair<uint8_t*, size_t>;
 
-  enum ChunkReadResult {
-    // Returned an error in parsing the cbor-encoded header.
-    CHUNK_DECODING_ERROR,
-    // Returned when max_wait expired before any data was read.
-    CHUNK_READ_TIMEOUT,
-    // Returned when a non-chunk message is received.
-    CHUNK_STREAM_ENDED,
-    // Returned when the processing callback does not return a value.
-    CHUNK_PROCESSING_ERROR,
-  };
-
   /*
    * Reads chunks of data from the given input stream, and invokes the given
    * callback to process each of them in turn.
@@ -71,7 +80,7 @@ class ChunkReader {
    */
   auto ReadChunkFromStream(
       std::function<std::optional<size_t>(uint8_t*, size_t)> callback,
-      TickType_t max_wait) -> EncodeReadResult;
+      TickType_t max_wait) -> ChunkReadResult;
 
  private:
   MessageBufferHandle_t* stream_;
diff --git a/src/audio/include/fatfs_audio_input.hpp b/src/audio/include/fatfs_audio_input.hpp
index 0fc2729f..6fe178ab 100644
--- a/src/audio/include/fatfs_audio_input.hpp
+++ b/src/audio/include/fatfs_audio_input.hpp
@@ -5,8 +5,9 @@
 #include <string>
 
 #include "freertos/FreeRTOS.h"
+
+#include "freertos/message_buffer.h"
 #include "freertos/queue.h"
-#include "freertos/stream_buffer.h"
 
 #include "audio_element.hpp"
 #include "storage.hpp"
@@ -18,11 +19,16 @@ class FatfsAudioInput : public IAudioElement {
   FatfsAudioInput(std::shared_ptr<drivers::SdStorage> storage);
   ~FatfsAudioInput();
 
-  auto OutputBuffer() -> MessageBufferHandle_t;
+  auto ProcessStreamInfo(StreamInfo&& info) -> cpp::result<void, StreamError>;
+  auto ProcessChunk(uint8_t* data, std::size_t length)
+      -> cpp::result<size_t, StreamError>;
+  auto ProcessIdle() -> cpp::result<void, StreamError>;
 
   auto SendChunk(uint8_t* buffer, size_t size) -> size_t;
 
  private:
+  auto GetRingBufferDistance() -> size_t;
+
   std::shared_ptr<drivers::SdStorage> storage_;
 
   uint8_t* file_buffer_;
@@ -39,7 +45,6 @@ class FatfsAudioInput : public IAudioElement {
 
   uint8_t* output_buffer_memory_;
   StaticMessageBuffer_t output_buffer_metadata_;
-  MessageBufferHandle_t output_buffer_;
 };
 
 }  // namespace audio
diff --git a/src/audio/include/stream_info.hpp b/src/audio/include/stream_info.hpp
index bf5d4c60..ca28dd4e 100644
--- a/src/audio/include/stream_info.hpp
+++ b/src/audio/include/stream_info.hpp
@@ -3,9 +3,13 @@
 #include <cstdint>
 #include <optional>
 #include <string>
-#include "esp-idf/components/cbor/tinycbor/src/cbor.h"
+
+#include "cbor.h"
 #include "result.hpp"
 
+#include "cbor_decoder.hpp"
+#include "cbor_encoder.hpp"
+
 namespace audio {
 
 class StreamInfo {
@@ -18,7 +22,7 @@ class StreamInfo {
 
   static auto Create(const uint8_t* buffer, size_t length)
       -> cpp::result<StreamInfo, ParseError>;
-  StreamInfo(CborValue& map);
+  StreamInfo(cbor::MapDecoder*);
 
   StreamInfo() = default;
   StreamInfo(const StreamInfo&) = default;
@@ -34,11 +38,7 @@ class StreamInfo {
     return sample_rate_;
   }
 
-  enum EncodeError {
-    OUT_OF_MEMORY,
-  };
-
-  auto WriteToMap(CborEncoder encoder) -> cpp::result<size_t, EncodeError>;
+  auto WriteToMap(cbor::Encoder& encoder) -> cpp::result<size_t, CborError>;
 
  private:
   std::optional<std::string> path_;
diff --git a/src/audio/stream_info.cpp b/src/audio/stream_info.cpp
index 6011571d..a5f7bebf 100644
--- a/src/audio/stream_info.cpp
+++ b/src/audio/stream_info.cpp
@@ -1,26 +1,31 @@
 #include "stream_info.hpp"
+
 #include <cstdint>
+#include <string>
+
+#include "cbor.h"
+
 #include "cbor_decoder.hpp"
-#include "esp-idf/components/cbor/tinycbor/src/cbor.h"
+#include "cbor_encoder.hpp"
 #include "stream_message.hpp"
 
 namespace audio {
 
-static const char* kKeyPath = "p";
-static const char* kKeyChannels = "c";
-static const char* kKeyBitsPerSample = "b";
-static const char* kKeySampleRate = "r";
+static const std::string kKeyPath = "p";
+static const std::string kKeyChannels = "c";
+static const std::string kKeyBitsPerSample = "b";
+static const std::string kKeySampleRate = "r";
 
-static auto StreamInfo::Create(const uint8_t* buffer, size_t length)
+auto StreamInfo::Create(const uint8_t* buffer, size_t length)
     -> cpp::result<StreamInfo, ParseError> {
   CborParser parser;
   CborValue value;
 
-  cbor_parser_init(buffer, len, 0, &parser, &value);
+  cbor_parser_init(buffer, length, 0, &parser, &value);
 
-  uint8_t type = 0;
-  if (!cbor_value_is_integer(&value) ||
-      !cbor_value_get_integer(&value, &type) || type != STREAM_INFO) {
+  int type = 0;
+  if (!cbor_value_is_integer(&value) || !cbor_value_get_int(&value, &type) ||
+      type != TYPE_STREAM_INFO) {
     return cpp::fail(WRONG_TYPE);
   }
 
@@ -30,26 +35,28 @@ static auto StreamInfo::Create(const uint8_t* buffer, size_t length)
     return cpp::fail(MISSING_MAP);
   }
 
-  return StreamInfo(value);
+  auto map_decoder = cbor::MapDecoder::Create(value);
+  if (map_decoder.has_value()) {
+    return StreamInfo(map_decoder.value().get());
+  }
+  return cpp::fail(CBOR_ERROR);
 }
 
-StreamInfo::StreamInfo(CborValue& map) {
+StreamInfo::StreamInfo(cbor::MapDecoder* decoder) {
   // TODO: this method is n^2, which seems less than ideal. But you don't do it
   // that frequently, so maybe it's okay? Needs investigation.
-  cbor::MapDecoder decoder(map);
-  channels_ = decoder.FindValue(kKeyChannels);
-  bits_per_sample_ = decoder.FindValue(kKeyBitsPerSample);
-  sample_rate_ = decoder.FindValue(kKeySampleRate);
-  path_ = decoder.FindValue(kKeyPath);
+  channels_ = decoder->FindValue<uint64_t>(kKeyChannels);
+  bits_per_sample_ = decoder->FindValue<uint64_t>(kKeyBitsPerSample);
+  sample_rate_ = decoder->FindValue<uint64_t>(kKeySampleRate);
+  path_ = decoder->FindValue<std::string>(kKeyPath);
 }
 
 auto StreamInfo::WriteToMap(cbor::Encoder& map_encoder)
-    -> cpp::result<size_t, EncodeError> {
-  CborEncoder map;
-  map_encoder.WriteKeyValue(kKeyChannels, channels_);
-  map_encoder.WriteKeyValue(kKeyBitsPerSample, bits_per_sample_);
-  map_encoder.WriteKeyValue(kKeySampleRate, sample_rate_);
-  map_encoder.WriteKeyValue(kKeyPath, path_);
+    -> cpp::result<size_t, CborError> {
+  map_encoder.WriteKeyValue<uint64_t>(kKeyChannels, channels_);
+  map_encoder.WriteKeyValue<uint64_t>(kKeyBitsPerSample, bits_per_sample_);
+  map_encoder.WriteKeyValue<uint64_t>(kKeySampleRate, sample_rate_);
+  map_encoder.WriteKeyValue<std::string>(kKeyPath, path_);
   return map_encoder.Finish();
 }
 
diff --git a/src/cbor/cbor_decoder.cpp b/src/cbor/cbor_decoder.cpp
deleted file mode 100644
index 20696afb..00000000
--- a/src/cbor/cbor_decoder.cpp
+++ /dev/null
@@ -1,131 +0,0 @@
-#include "cbor_decoder.hpp"
-#include <cstdint>
-#include "esp-idf/components/cbor/tinycbor/src/cbor.h"
-#include "include/cbor_decoder.hpp"
-
-namespace cbor {
-
-static auto ArrayDecoder::Create(uint8_t* buffer, size_t buffer_len)
-    -> cpp::result<std::unique_ptr<ArrayDecoder>, CborError> {
-  auto decoder = std::make_unique<ArrayDecoder>();
-  cbor_parser_init(buffer, buffer_len, &decoder->parser_, &decoder->root_);
-  if (!cbor_value_is_array(&decoder->root_)) {
-    return cpp::fail(CborErrorIllegalType);
-  }
-  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
-  if (err != CborNoError) {
-    return cpp::fail(err);
-  }
-  return std::move(decoder);
-}
-
-static auto ArrayDecoder::Create(CborValue& root)
-    -> cpp::result<std::unique_ptr<ArrayDecoder>, CborError> {
-  auto decoder = std::make_unique<ArrayDecoder>();
-  decoder->root_ = root;
-  if (!cbor_value_is_array(&decoder->root_)) {
-    return cpp::fail(CborErrorIllegalType);
-  }
-
-  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
-  if (err != CborNoError) {
-    return cpp::fail(err);
-  }
-  return std::move(decoder);
-}
-
-static auto MapDecoder::Create(uint8_t* buffer, size_t buffer_len)
-    -> cpp::result<std::unique_ptr<MapDecoder>, CborError> {
-  auto decoder = std::make_unique<MapDecoder>();
-  cbor_parser_init(buffer, buffer_len, &decoder->parser_, &decoder->root_);
-  if (!cbor_value_is_map(&decoder->root_)) {
-    return cpp::fail(CborErrorIllegalType);
-  }
-  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
-  if (err != CborNoError) {
-    return cpp::fail(err);
-  }
-  return std::move(decoder);
-}
-
-static auto MapDecoder::Create(CborValue& root)
-    -> cpp::result<std::unique_ptr<MapDecoder>, CborError> {
-  auto decoder = std::make_unique<MapDecoder>();
-  decoder->root_ = root;
-  if (!cbor_value_is_map(&decoder->root_)) {
-    return cpp::fail(CborErrorIllegalType);
-  }
-  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
-  if (err != CborNoError) {
-    return cpp::fail(err);
-  }
-  return std::move(decoder);
-}
-
-auto MapDecoder::FindString(const std::string& key)
-    -> std::optional<std::string> {
-  CborValue val;
-  if (error_ != CborNoError) {
-    return {};
-  }
-  if (cbor_value_map_find_value(&it_, key.c_str(), &val) != CborNoError) {
-    return {};
-  }
-  if (!cbor_value_is_byte_string(&val)) {
-    error_ = CborErrorIllegalType;
-    return {};
-  }
-  uint8_t* buf;
-  size_t len;
-  error_ = cbor_value_dup_byte_string(&val, &buf, &len, NULL);
-  if (error_ != CborNoError) {
-    return cpp::fail(error_);
-  }
-  std::string ret(buf, len);
-  free(buf);
-  return ret;
-}
-
-auto MapDecoder::FindUnsigned(const std::string& key)
-    -> std::optional<uint32_t> {
-  CborValue val;
-  if (error_ != CborNoError) {
-    return {};
-  }
-  if (cbor_value_map_find_value(&it_, key.c_str(), &val) != CborNoError) {
-    return {};
-  }
-  if (!cbor_value_is_unsigned_integer(&val)) {
-    error_ = CborErrorIllegalType;
-    return {};
-  }
-  uint64_t ret;
-  error_ = cbor_value_get_uint64(&val, &ret);
-  if (error_ != CborNoError) {
-    return cpp::fail(error_);
-  }
-  return ret;
-}
-
-auto MapDecoder::FindSigned(const std::string& key) -> std::optional<int32_t> {
-  CborValue val;
-  if (error_ != CborNoError) {
-    return {};
-  }
-  if (cbor_value_map_find_value(&it_, key.c_str(), &val) != CborNoError) {
-    // Don't store this as an error; missing keys are fine.
-    return {};
-  }
-  if (!cbor_value_is_integer(&val)) {
-    error_ = CborErrorIllegalType;
-    return {};
-  }
-  int32_t ret;
-  error_ = cbor_value_get_int(&val, &ret);
-  if (error_ != CborNoError) {
-    return cpp::fail(error_);
-  }
-  return ret;
-}
-
-}  // namespace cbor
diff --git a/src/cbor/CMakeLists.txt b/src/cbor_wrapper/CMakeLists.txt
index cd5186e0..cd5186e0 100644
--- a/src/cbor/CMakeLists.txt
+++ b/src/cbor_wrapper/CMakeLists.txt
diff --git a/src/cbor_wrapper/cbor_decoder.cpp b/src/cbor_wrapper/cbor_decoder.cpp
new file mode 100644
index 00000000..a99cca02
--- /dev/null
+++ b/src/cbor_wrapper/cbor_decoder.cpp
@@ -0,0 +1,112 @@
+#include "cbor_decoder.hpp"
+
+#include <cstdint>
+#include <string>
+
+#include "cbor.h"
+#include "result.hpp"
+
+static const int kDecoderFlags = 0;
+
+namespace cbor {
+
+auto parse_stdstring(const CborValue* val, std::string* out) -> CborError {
+  char* buf;
+  size_t len;
+  CborError err = cbor_value_dup_text_string(val, &buf, &len, NULL);
+  if (err != CborNoError) {
+    return err;
+  }
+  *out = std::string(buf, len);
+  free(buf);
+  return err;
+}
+
+auto ArrayDecoder::Create(uint8_t* buffer, size_t buffer_len)
+    -> cpp::result<std::unique_ptr<ArrayDecoder>, CborError> {
+  auto decoder = std::make_unique<ArrayDecoder>();
+  cbor_parser_init(buffer, buffer_len, kDecoderFlags, &decoder->parser_,
+                   &decoder->root_);
+  if (!cbor_value_is_array(&decoder->root_)) {
+    return cpp::fail(CborErrorIllegalType);
+  }
+  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
+  if (err != CborNoError) {
+    return cpp::fail(err);
+  }
+  return std::move(decoder);
+}
+
+auto ArrayDecoder::Create(CborValue& root)
+    -> cpp::result<std::unique_ptr<ArrayDecoder>, CborError> {
+  auto decoder = std::make_unique<ArrayDecoder>();
+  decoder->root_ = root;
+  if (!cbor_value_is_array(&decoder->root_)) {
+    return cpp::fail(CborErrorIllegalType);
+  }
+
+  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
+  if (err != CborNoError) {
+    return cpp::fail(err);
+  }
+  return std::move(decoder);
+}
+
+template <>
+auto ArrayDecoder::NextValue() -> cpp::result<int64_t, CborError> {
+  return NextValue(&cbor_value_is_integer, &cbor_value_get_int);
+}
+template <>
+auto ArrayDecoder::NextValue() -> cpp::result<uint64_t, CborError> {
+  return NextValue(&cbor_value_is_unsigned_integer, &cbor_value_get_uint64);
+}
+template <>
+auto ArrayDecoder::NextValue() -> cpp::result<std::string, CborError> {
+  return NextValue(&cbor_value_is_byte_string, &parse_stdstring);
+}
+
+auto MapDecoder::Create(uint8_t* buffer, size_t buffer_len)
+    -> cpp::result<std::unique_ptr<MapDecoder>, CborError> {
+  auto decoder = std::make_unique<MapDecoder>();
+  cbor_parser_init(buffer, buffer_len, kDecoderFlags, &decoder->parser_,
+                   &decoder->root_);
+  if (!cbor_value_is_map(&decoder->root_)) {
+    return cpp::fail(CborErrorIllegalType);
+  }
+  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
+  if (err != CborNoError) {
+    return cpp::fail(err);
+  }
+  return std::move(decoder);
+}
+
+auto MapDecoder::Create(CborValue& root)
+    -> cpp::result<std::unique_ptr<MapDecoder>, CborError> {
+  auto decoder = std::make_unique<MapDecoder>();
+  decoder->root_ = root;
+  if (!cbor_value_is_map(&decoder->root_)) {
+    return cpp::fail(CborErrorIllegalType);
+  }
+  CborError err = cbor_value_enter_container(&decoder->root_, &decoder->it_);
+  if (err != CborNoError) {
+    return cpp::fail(err);
+  }
+  return std::move(decoder);
+}
+
+template <>
+auto MapDecoder::FindValue(const std::string& key) -> std::optional<int64_t> {
+  return FindValue(key, &cbor_value_is_integer, &cbor_value_get_int);
+}
+template <>
+auto MapDecoder::FindValue(const std::string& key) -> std::optional<uint64_t> {
+  return FindValue(key, &cbor_value_is_unsigned_integer,
+                   &cbor_value_get_uint64);
+}
+template <>
+auto MapDecoder::FindValue(const std::string& key)
+    -> std::optional<std::string> {
+  return FindValue(key, &cbor_value_is_byte_string, &parse_stdstring);
+}
+
+}  // namespace cbor
diff --git a/src/cbor/cbor_encoder.cpp b/src/cbor_wrapper/cbor_encoder.cpp
index 6940917e..e4e8ee84 100644
--- a/src/cbor/cbor_encoder.cpp
+++ b/src/cbor_wrapper/cbor_encoder.cpp
@@ -1,6 +1,11 @@
 #include "cbor_encoder.hpp"
+
 #include <cstdint>
-#include "esp-idf/components/cbor/tinycbor/src/cbor.h"
+#include <string>
+
+#include "cbor.h"
+#include "cbor_decoder.hpp"
+#include "result.hpp"
 
 namespace cbor {
 
@@ -10,15 +15,15 @@ Encoder::Encoder(ContainerType type,
                  uint32_t container_len,
                  uint8_t* buffer,
                  size_t buffer_len) {
-  cbor_encoder_init(&root_encoder, buffer, buffer_len, kEncoderFlags);
+  cbor_encoder_init(&root_encoder_, buffer, buffer_len, kEncoderFlags);
   switch (type) {
     case CONTAINER_ARRAY:
-      error_ = cbor_encoder_create_array(&encoder, &container_encoder_,
+      error_ = cbor_encoder_create_array(&root_encoder_, &container_encoder_,
                                          container_len);
       break;
     case CONTAINER_MAP:
-      error_ =
-          cbor_encoder_create_map(&encoder, &container_encoder_, container_len);
+      error_ = cbor_encoder_create_map(&root_encoder_, &container_encoder_,
+                                       container_len);
       break;
   }
 }
@@ -28,7 +33,7 @@ auto Encoder::WriteValue(const std::string& val) -> void {
     return;
   }
   error_ =
-      cbor_encode_byte_string(&container_encoder_, val.c_str(), val.size());
+      cbor_encode_text_string(&container_encoder_, val.c_str(), val.size());
 }
 
 auto Encoder::WriteValue(uint32_t val) -> void {
@@ -46,15 +51,13 @@ auto Encoder::WriteValue(int32_t val) -> void {
 }
 
 auto Encoder::Finish() -> cpp::result<size_t, CborError> {
+  if (error_ == CborNoError) {
+    error_ = cbor_encoder_close_container(&root_encoder_, &container_encoder_);
+  }
   if (error_ != CborNoError) {
     return cpp::fail(error_);
   }
-  if (CborError final_error =
-          cbor_encoder_close_container(&root_encoder, &container_encoder_) !=
-          CborNoError) {
-    return cpp::fail(final_error);
-  }
-  return cbor_encoder_get_buffer_size(&root_encoder);
+  return cbor_encoder_get_buffer_size(&root_encoder_, buffer_);
 }
 
 }  // namespace cbor
diff --git a/src/cbor/include/cbor_decoder.hpp b/src/cbor_wrapper/include/cbor_decoder.hpp
index 879a1efa..193e7843 100644
--- a/src/cbor/include/cbor_decoder.hpp
+++ b/src/cbor_wrapper/include/cbor_decoder.hpp
@@ -3,23 +3,13 @@
 #include <stdint.h>
 
 #include <cstdint>
+#include <string>
 
 #include "cbor.h"
+#include "result.hpp"
 
 namespace cbor {
 
-static auto parse_stdstring(CborValue* val, std::string* out) -> CborError {
-  uint8_t* buf;
-  size_t len;
-  CborError err = cbor_value_dup_byte_string(val, &buf, &len, NULL);
-  if (err != CborNoError) {
-    return err;
-  }
-  *out = std::move(std::string(buf, len));
-  free(buf);
-  return err
-}
-
 class ArrayDecoder {
  public:
   static auto Create(uint8_t* buffer, size_t buffer_len)
@@ -28,25 +18,14 @@ class ArrayDecoder {
   static auto Create(CborValue& root)
       -> cpp::result<std::unique_ptr<ArrayDecoder>, CborError>;
 
+  ArrayDecoder() {}
+
   template <typename T>
   auto NextValue() -> cpp::result<T, CborError>;
 
-  template <>
-  auto NextValue() -> cpp::result<int64_t, CborError> {
-    return NextValue(&cbor_value_is_integer, &cbor_value_get_int);
-  }
-  template <>
-  auto NextValue() -> cpp::result<uint64_t, CborError> {
-    return NextValue(&cbor_value_is_unsigned_integer, &cbor_value_get_uint64);
-  }
-  template <>
-  auto NextValue() -> cpp::result<std::string, CborError> {
-    return NextValue(&cbor_value_is_byte_string, &parse_stdstring);
-  }
-
   template <typename T>
-  auto NextValue(bool (*is_valid)(CborValue*),
-                 CborError (*parse)(CborValue*, T*))
+  auto NextValue(bool (*is_valid)(const CborValue*),
+                 CborError (*parse)(const CborValue*, T*))
       -> cpp::result<T, CborError> {
     if (error_ != CborNoError) {
       return cpp::fail(error_);
@@ -90,30 +69,19 @@ class MapDecoder {
   static auto Create(CborValue& root)
       -> cpp::result<std::unique_ptr<MapDecoder>, CborError>;
 
+  MapDecoder() {}
+
   template <typename T>
   auto FindValue(const std::string& key) -> std::optional<T>;
 
-  template <>
-  auto FindValue(const std::string& key) -> std::optional<int64_t> {
-    return FindValue(key, &cbor_value_is_integer, &cbor_value_get_int);
-  }
-  template <>
-  auto FindValue(const std::string& key) -> std::optional<uint64_t> {
-    return FindValue(key, &cbor_value_is_unsigned_integer,
-                     &cbor_value_get_uint64);
-  }
-  template <>
-  auto FindValue(const std::string& key) -> std::optional<std::string> {
-    return FindValue(key, &cbor_value_is_byte_string, &parse_stdstring);
-  }
-
   template <typename T>
   auto FindValue(const std::string& key,
-                 bool (*is_valid)(CborValue*),
-                 CborError (*parse)(CborValue*, T*)) -> std::optional<T> {
+                 bool (*is_valid)(const CborValue*),
+                 CborError (*parse)(const CborValue*, T*)) -> std::optional<T> {
     if (error_ != CborNoError) {
       return {};
     }
+    CborValue val;
     if (cbor_value_map_find_value(&it_, key.c_str(), &val) != CborNoError) {
       return {};
     }
@@ -124,7 +92,7 @@ class MapDecoder {
     T ret;
     error_ = parse(&val, &ret);
     if (error_ != CborNoError) {
-      return cpp::fail(error_);
+      return {};
     }
     return ret;
   }
diff --git a/src/cbor/include/cbor_encoder.hpp b/src/cbor_wrapper/include/cbor_encoder.hpp
index 8f5214f6..cc57e8a4 100644
--- a/src/cbor/include/cbor_encoder.hpp
+++ b/src/cbor_wrapper/include/cbor_encoder.hpp
@@ -1,28 +1,40 @@
 #pragma once
 
 #include <cstdint>
+#include <optional>
+#include <string>
 
 #include "cbor.h"
+#include "result.hpp"
 
 namespace cbor {
 
+enum ContainerType { CONTAINER_ARRAY, CONTAINER_MAP };
+
 class Encoder {
  public:
-  enum ContainerType { CONTAINER_ARRAY, CONTAINER_MAP };
   Encoder(ContainerType type,
           uint32_t container_len,
           uint8_t* buffer,
           size_t buffer_len);
 
+  auto WriteValue(const std::string& val) -> void;
+  auto WriteValue(uint32_t val) -> void;
+  auto WriteValue(int32_t val) -> void;
+
   template <typename T>
-  auto WriteKeyValue(const std::string& key, const T& val) -> void {
+  auto WriteKeyValue(const std::string& key, const T&& val) -> void {
     WriteValue(key);
     WriteValue(val);
   }
 
-  auto WriteValue(const std::string& val) -> void;
-  auto WriteValue(uint32_t val) -> void;
-  auto WriteValue(int32_t val) -> void;
+  template <typename T>
+  auto WriteKeyValue(const std::string& key, const std::optional<T>& val)
+      -> void {
+    if (val) {
+      WriteKeyValue<T>(key, val.value());
+    }
+  }
 
   auto Finish() -> cpp::result<size_t, CborError>;
 
@@ -30,6 +42,7 @@ class Encoder {
   Encoder& operator=(const Encoder&) = delete;
 
  private:
+  uint8_t* buffer_;
   CborEncoder root_encoder_;
   CborEncoder container_encoder_;
 
diff --git a/src/codecs/CMakeLists.txt b/src/codecs/CMakeLists.txt
index 4a8918ae..4f89f370 100644
--- a/src/codecs/CMakeLists.txt
+++ b/src/codecs/CMakeLists.txt
@@ -1,6 +1,8 @@
 idf_component_register(
   SRCS "codec.cpp" "mad.cpp"
-  INCLUDE_DIRS "include")
+  INCLUDE_DIRS "include"
+  REQUIRES "result")
 
-target_compile_options(${COMPONENT_LIB} PRIVATE ${EXTRA_WARNINGS})
 add_dependencies("${COMPONENT_LIB}" libmad)
+target_compile_options("${COMPONENT_LIB}" PRIVATE ${EXTRA_WARNINGS})
+target_include_directories("${COMPONENT_LIB}" PRIVATE "${LIBMAD_INCLUDE}")
diff --git a/src/codecs/codec.cpp b/src/codecs/codec.cpp
index db8d69b9..2a66b5f1 100644
--- a/src/codecs/codec.cpp
+++ b/src/codecs/codec.cpp
@@ -1,10 +1,13 @@
 #include "codec.hpp"
 
+#include <memory>
+#include "mad.hpp"
+
 namespace codecs {
 
 auto CreateCodecForExtension(std::string extension)
     -> cpp::result<std::unique_ptr<ICodec>, CreateCodecError> {
-  return cpp::fail(UNKNOWN_EXTENSION);
+  return std::make_unique<MadMp3Decoder>();  // TODO.
 }
 
 }  // namespace codecs
diff --git a/src/codecs/include/codec.hpp b/src/codecs/include/codec.hpp
index 8e82bd71..764b63fc 100644
--- a/src/codecs/include/codec.hpp
+++ b/src/codecs/include/codec.hpp
@@ -1,18 +1,17 @@
 #pragma once
 
 #include <stdint.h>
+
 #include <cstddef>
 #include <cstdint>
+#include <memory>
+#include <string>
+#include <utility>
 
 #include "result.hpp"
 
 namespace codecs {
 
-enum CreateCodecError { UNKNOWN_EXTENSION };
-
-auto CreateCodecForFile(const std::string& extension)
-    -> cpp::result<std::unique_ptr<ICodec>, CreateCodecError>;
-
 class ICodec {
  public:
   virtual ~ICodec() {}
@@ -22,39 +21,48 @@ class ICodec {
   struct OutputFormat {
     uint8_t num_channels;
     uint8_t bits_per_sample;
-    int sample_rate_hz;
+    uint32_t sample_rate_hz;
   };
 
   virtual auto GetOutputFormat() -> OutputFormat = 0;
 
-  enum ProcessingError {};
-
-  struct Result {
-    bool need_more_input;
-    /*
-     * For need_more_input, this is how far we got in the input buffer
-     * before we were unable to process more data. Any remaining data in the
-     * buffer should be moved to the start before the next call.
-     */
-    std::size_t input_processed;
-
-    bool flush_output;
-    /*
-     * For flush_output, this is how far we got in the output buffer before
-     * we ran out of space for samples. The caller should flush this many
-     * bytes downstream.
-     */
-    std::size_t output_written;
-  };
+  enum ProcessingError { MALFORMED_DATA };
 
   virtual auto ResetForNewStream() -> void = 0;
 
-  virtual auto SetInput(uint8_t* buffer, std::size_t length) = 0;
-  virtual auto Process(uint8_t* output, std::size_t output_length)
-      -> cpp::result<size_t, Error> = 0;
-
-  virtual auto GetOutputProcessed() -> std::size_t;
-  = 0;
+  virtual auto SetInput(uint8_t* buffer, std::size_t length) -> void = 0;
+
+  /*
+   * Returns the codec's next read position within the input buffer. If the
+   * codec is out of usable data, but there is still some data left in the
+   * stream, that data should be prepended to the next input buffer.
+   */
+  virtual auto GetInputPosition() -> std::size_t = 0;
+
+  /*
+   * Read one frame (or equivalent discrete chunk) from the input, and
+   * synthesize output samples for it.
+   *
+   * Returns true if we are out of usable data from the input stream, or false
+   * otherwise.
+   */
+  virtual auto ProcessNextFrame() -> cpp::result<bool, ProcessingError> = 0;
+
+  /*
+   * Writes PCM samples to the given output buffer.
+   *
+   * Returns the number of bytes that were written, and true if all of the
+   * samples synthesized from the last call to `ProcessNextFrame` have been
+   * written. If this returns false, then this method should be called again
+   * after flushing the output buffer.
+   */
+  virtual auto WriteOutputSamples(uint8_t* output, std::size_t output_length)
+      -> std::pair<std::size_t, bool> = 0;
 };
 
+enum CreateCodecError { UNKNOWN_EXTENSION };
+
+auto CreateCodecForFile(const std::string& extension)
+    -> cpp::result<std::unique_ptr<ICodec>, CreateCodecError>;
+
 }  // namespace codecs
diff --git a/src/codecs/include/mad.hpp b/src/codecs/include/mad.hpp
index 241ea6c3..aa24f3c9 100644
--- a/src/codecs/include/mad.hpp
+++ b/src/codecs/include/mad.hpp
@@ -1,5 +1,11 @@
 #pragma once
 
+#include <cstddef>
+#include <cstdint>
+#include <string>
+
+#include "mad.h"
+
 #include "codec.hpp"
 
 namespace codecs {
@@ -9,10 +15,14 @@ class MadMp3Decoder : public ICodec {
   MadMp3Decoder();
   ~MadMp3Decoder();
 
-  auto ProcessInput(Result* res, uint8_t* input, std::size_t input_len) -> void;
-  auto WriteOutputSamples(Result* res,
-                          uint8_t* output,
-                          std::size_t output_length) -> void;
+  auto CanHandleFile(const std::string& path) -> bool override;
+  auto GetOutputFormat() -> OutputFormat override;
+  auto ResetForNewStream() -> void override;
+  auto SetInput(uint8_t* buffer, std::size_t length) -> void override;
+  auto GetInputPosition() -> std::size_t override;
+  auto ProcessNextFrame() -> cpp::result<bool, ProcessingError> override;
+  auto WriteOutputSamples(uint8_t* output, std::size_t output_length)
+      -> std::pair<std::size_t, bool> override;
 
  private:
   mad_stream stream_;
@@ -22,7 +32,7 @@ class MadMp3Decoder : public ICodec {
   mad_header header_;
   bool has_decoded_header_;
 
-  int current_sample_ = -1;
+  int current_sample_;
 };
 
 }  // namespace codecs
diff --git a/src/codecs/mad.cpp b/src/codecs/mad.cpp
index c918e849..4afc9a77 100644
--- a/src/codecs/mad.cpp
+++ b/src/codecs/mad.cpp
@@ -1,8 +1,11 @@
 #include "mad.hpp"
+
 #include <cstdint>
 
 #include "mad.h"
 
+#include "codec.hpp"
+
 namespace codecs {
 
 static int32_t scaleTo24Bits(mad_fixed_t sample) {
@@ -32,118 +35,99 @@ MadMp3Decoder::~MadMp3Decoder() {
   mad_header_finish(&header_);
 }
 
-auto MadMp3Decoder::CanHandleExtension(std::string extension) -> bool {
-  return extension == "mp3";
+auto MadMp3Decoder::CanHandleFile(const std::string& path) -> bool {
+  return true;  // TODO.
 }
 
-auto GetOutputFormat() -> OutputFormat {
+auto MadMp3Decoder::GetOutputFormat() -> OutputFormat {
   return OutputFormat{
-      .num_channels = synth_.pcm.channels,
+      .num_channels = static_cast<uint8_t>(synth_.pcm.channels),
       .bits_per_sample = 24,
       .sample_rate_hz = synth_.pcm.samplerate,
   };
 }
 
-auto MadMp3Decoder::Process(uint8_t* input,
-                            std::size_t input_len,
-                            uint8_t* output,
-                            std::size_t output_length)
-    -> cpp::result<Result, Error> {
-  Result res {
-    .need_more_input = false, .input_processed = 0, .flush_output = false,
-    .output_written = 0,
-  }
-  while (true) {
-    // Only process more of the input if we're done sending off the
-    // samples for the previous frame.
-    if (current_sample_ == -1) {
-      ProcessInput(&res, input, input_len);
-    }
+auto MadMp3Decoder::ResetForNewStream() -> void {
+  has_decoded_header_ = false;
+}
 
-    // Write PCM samples to the output buffer. This always needs to be
-    // done, even if we ran out of input, so that we don't keep the last
-    // few samples buffered if the input stream has actually finished.
-    WriteOutputSamples(&res, output, output_length);
+auto MadMp3Decoder::SetInput(uint8_t* buffer, std::size_t length) -> void {
+  mad_stream_buffer(&stream_, buffer, length);
+}
 
-    if (res.need_more_input || res.flush_output) {
-      return res;
-    }
-  }
+auto MadMp3Decoder::GetInputPosition() -> std::size_t {
+  return stream_.next_frame - stream_.buffer;
+}
 
-  auto MadMp3Decoder::ProcessInput(Result * res, uint8_t * input,
-                                   std::size_t input_len)
-      ->void {
-    if (input != stream_.buffer) {
-      mad_stream_buffer(&stream_, input, input_len);
-    }
+auto MadMp3Decoder::ProcessNextFrame() -> cpp::result<bool, ProcessingError> {
+  if (!has_decoded_header_) {
+    // The header of any given frame should be representative of the
+    // entire stream, so only need to read it once.
+    mad_header_decode(&header_, &stream_);
+    has_decoded_header_ = true;
 
-    if (!has_decoded_header_) {
-      // The header of any given frame should be representative of the
-      // entire stream, so only need to read it once.
-      mad_header_decode(&header_, &stream);
-      has_decoded_header_ = true;
+    // TODO: Use the info in the header for something. I think the
+    // duration will help with seeking?
+  }
 
-      // TODO: Use the info in the header for something. I think the
-      // duration will help with seeking?
+  // Whatever was last synthesized is now invalid, so ensure we don't try to
+  // send it.
+  current_sample_ = -1;
+
+  // Decode the next frame. To signal errors, this returns -1 and
+  // stashes an error code in the stream structure.
+  if (mad_frame_decode(&frame_, &stream_) < 0) {
+    if (MAD_RECOVERABLE(stream_.error)) {
+      // Recoverable errors are usually malformed parts of the stream.
+      // We can recover from them by just retrying the decode.
+      return false;
     }
 
-    // Decode the next frame. To signal errors, this returns -1 and
-    // stashes an error code in the stream structure.
-    if (mad_frame_decode(&frame_, &stream_) < 0) {
-      if (MAD_RECOVERABLE(stream_.error)) {
-        // Recoverable errors are usually malformed parts of the stream.
-        // We can recover from them by just retrying the decode.
-        continue;
-      }
-
-      if (stream_.error = MAD_ERROR_BUFLEN) {
-        // The decoder ran out of bytes before it completed a frame. We
-        // need to return back to the caller to give us more data. Note
-        // that there might still be some unused data in the input, so we
-        // should calculate that amount and return it.
-        size_t remaining_bytes = stream.bufend - stream_.next_frame;
-        return remaining_bytes;
-      }
-
-      // The error is unrecoverable. Give up.
-      return cpp::fail(MALFORMED_DATA);
+    if (stream_.error == MAD_ERROR_BUFLEN) {
+      // The decoder ran out of bytes before it completed a frame. We
+      // need to return back to the caller to give us more data.
+      return true;
     }
 
-    // We've successfully decoded a frame!
-    // Now we need to synthesize PCM samples based on the frame, and send
-    // them downstream.
-    mad_synth_frame(&synth_, &frame_);
-    up_to_sample = 0;
+    // The error is unrecoverable. Give up.
+    return cpp::fail(MALFORMED_DATA);
   }
 
-  auto MadMp3Decoder::WriteOutputSamples(Result * res, uint8_t * output,
-                                         std::size_t output_length)
-      ->void {
-    size_t output_byte = 0;
-    // First ensure that we actually have some samples to send off.
-    if (current_sample_ < 0) {
-      return;
-    }
-    res->flush_output = true;
-
-    while (current_sample_ < synth_.pcm.length) {
-      if (output_byte + (3 * synth_.pcm.channels) >= output_length) {
-        res->output_written = output_byte;
-        return;
-      }
-
-      for (int channel = 0; channel < synth_.pcm.channels; channel++) {
-        uint32_t sample_24 = scaleTo24Bits(synth_.pcm.samples[channel][sample]);
-        output[output_byte++] = (sample_24 >> 0) & 0xff;
-        output[output_byte++] = (sample_24 >> 8) & 0xff;
-        output[output_byte++] = (sample_24 >> 16) & 0xff;
-      }
-      current_sample_++;
+  // We've successfully decoded a frame!
+  // Now we need to synthesize PCM samples based on the frame, and send
+  // them downstream.
+  mad_synth_frame(&synth_, &frame_);
+  current_sample_ = 0;
+  return false;
+}
+
+auto MadMp3Decoder::WriteOutputSamples(uint8_t* output,
+                                       std::size_t output_length)
+    -> std::pair<std::size_t, bool> {
+  size_t output_byte = 0;
+  // First ensure that we actually have some samples to send off.
+  if (current_sample_ < 0) {
+    return std::make_pair(output_byte, true);
+  }
+
+  while (current_sample_ < synth_.pcm.length) {
+    if (output_byte + (3 * synth_.pcm.channels) >= output_length) {
+      return std::make_pair(output_byte, false);
     }
 
-    // We wrote everything! Reset, ready for the next frame.
-    current_sample_ = -1;
-    res->output_written = output_byte;
+    for (int channel = 0; channel < synth_.pcm.channels; channel++) {
+      uint32_t sample_24 =
+          scaleTo24Bits(synth_.pcm.samples[channel][current_sample_]);
+      output[output_byte++] = (sample_24 >> 0) & 0xff;
+      output[output_byte++] = (sample_24 >> 8) & 0xff;
+      output[output_byte++] = (sample_24 >> 16) & 0xff;
+    }
+    current_sample_++;
   }
 
+  // We wrote everything! Reset, ready for the next frame.
+  current_sample_ = -1;
+  return std::make_pair(output_byte, true);
+}
+
 }  // namespace codecs
diff --git a/src/main/app_console.hpp b/src/main/app_console.hpp
index d41810b0..155d8127 100644
--- a/src/main/app_console.hpp
+++ b/src/main/app_console.hpp
@@ -9,8 +9,8 @@ namespace console {
 
 class AppConsole : public Console {
  public:
-  AppConsole(){};
-  virtual ~AppConsole(){};
+  AppConsole() {}
+  virtual ~AppConsole() {}
 
  protected:
   virtual auto RegisterExtraComponents() -> void;
diff --git a/src/main/main.cpp b/src/main/main.cpp
index 79a2f42b..3e073401 100644
--- a/src/main/main.cpp
+++ b/src/main/main.cpp
@@ -110,6 +110,7 @@ extern "C" void app_main(void) {
                                 (void*)lvglArgs, 1, sLvglStack,
                                 &sLvglTaskBuffer, 1);
 
+  /*
   ESP_LOGI(TAG, "Init audio output (I2S)");
   auto sink_res = drivers::I2SAudioOutput::create(expander);
   if (sink_res.has_error()) {
@@ -118,7 +119,6 @@ extern "C" void app_main(void) {
   }
   std::unique_ptr<drivers::IAudioOutput> sink = std::move(sink_res.value());
 
-  /*
   ESP_LOGI(TAG, "Init audio pipeline");
   auto playback_res = drivers::AudioPlayback::create(std::move(sink));
   if (playback_res.has_error()) {
@@ -131,7 +131,7 @@ extern "C" void app_main(void) {
   */
 
   ESP_LOGI(TAG, "Launch console");
-  console::AppConsole console(playback.get());
+  console::AppConsole console;
   console.Launch();
 
   while (1) {