2 files changed, 57 insertions, 2 deletions
diff --git a/src/codecs/include/codec.hpp b/src/codecs/include/codec.hpp
index 5e8763a6..99e786d5 100644
--- a/src/codecs/include/codec.hpp
+++ b/src/codecs/include/codec.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <stdint.h>
 #include <cstddef>
 #include <cstdint>
 
@@ -7,7 +8,9 @@
 
 namespace codecs {
 
-  enum CreateCodecError {};
+  enum CreateCodecError {
+    UNKNOWN_EXTENSION
+  };
 
   auto CreateCodecForExtension(std::string extension) -> cpp::result<std::unique_ptr<ICodec>, CreateCodecError>;
 
@@ -17,13 +20,39 @@ namespace codecs {
 
       virtual auto CanHandleExtension(std::string extension) -> bool = 0;
 
+      struct OutputFormat {
+        uint8_t num_channels;
+        uint8_t bits_per_sample;
+        int sample_rate_hz;
+      };
+
+      virtual auto GetOutputFormat() -> OutputFormat = 0;
+
       enum Error {};
 
+      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;
+      };
+
       virtual auto Process(
           uint8_t *input,
           std::size_t input_len,
           uint8_t *output,
-	  std::size_t output_length) -> cpp::result<size_t, Error>  = 0;
+	  std::size_t output_length) -> cpp::result<Result, Error>  = 0;
   };
 
 } // namespace codecs
diff --git a/src/codecs/include/mad.hpp b/src/codecs/include/mad.hpp
new file mode 100644
index 00000000..cfe4eab7
--- /dev/null
+++ b/src/codecs/include/mad.hpp
@@ -0,0 +1,26 @@
+#pragma once
+
+#include "codec.hpp"
+
+namespace codecs {
+
+  class MadMp3Decoder : public ICodec {
+    public:
+      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;
+
+    private:
+      mad_stream stream_;
+      mad_frame	frame_;
+      mad_synth	synth_;
+
+      mad_header header_;
+      bool has_decoded_header_;
+
+      int current_sample_ = -1;
+  };
+
+} // namespace codecs