diff --git a/system/stack/mmc/mmc_interface/mmc_interface.h b/system/stack/mmc/mmc_interface/mmc_interface.h
new file mode 100644
index 0000000000000000000000000000000000000000..a6c35f0c6cb44d18814d6047872d462c41402db8
--- /dev/null
+++ b/system/stack/mmc/mmc_interface/mmc_interface.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MMC_MMC_INTERFACE_MMC_INTERFACE_H_
+#define MMC_MMC_INTERFACE_MMC_INTERFACE_H_
+
+#include <stdint.h>
+
+#include "mmc/proto/mmc_config.pb.h"
+
+namespace mmc {
+
+// An abstract interface representing either an encoder or a decoder.
+class MmcInterface {
+ public:
+  virtual ~MmcInterface() = default;
+
+  // Builds and configures the encoder/decoder instance.
+  //
+  // Returns:
+  //   Input frame size accepted by the transcoder, if init succeeded.
+  //   Negative errno on error, otherwise.
+  virtual int init(ConfigParam config) = 0;
+
+  // Resets the encoder/decoder instance.
+  virtual void cleanup() = 0;
+
+  // Transcodes data in |i_buf|, and stores the result in |o_buf|.
+  //
+  // Returns:
+  //   Transcoded data length, if transcode succeeded.
+  //   Negative errno on error, otherwise.
+  virtual int transcode(uint8_t* i_buf, int i_len, uint8_t* o_buf,
+                        int o_len) = 0;
+};
+
+}  // namespace mmc
+
+#endif  // MMC_MMC_INTERFACE_MMC_INTERFACE_H_
diff --git a/system/stack/mmc/proto/BUILD.gn b/system/stack/mmc/proto/BUILD.gn
index 5e766a9d10ad1383f2d71eb7eaf0e961efdc3a9d..01a4c7c66daa1bbe4d7383c0a86528102bd38a60 100644
--- a/system/stack/mmc/proto/BUILD.gn
+++ b/system/stack/mmc/proto/BUILD.gn
@@ -24,3 +24,13 @@ proto_library("mmc_config_proto") {
   ]
   standalone=true
 }
+
+proto_library("mmc_service_proto") {
+  proto_in_dir = "./"
+  proto_out_dir = "include/mmc/proto"
+  sources = [
+    "${proto_in_dir}/mmc_service.proto",
+  ]
+  deps = [ ":mmc_config_proto" ]
+  standalone=true
+}
diff --git a/system/stack/mmc/proto/mmc_config.proto b/system/stack/mmc/proto/mmc_config.proto
index 5c4466f9ed8d30bb7b6cb4ae0a4b5abf57345bd8..58d3733783edb26586890f840b0c7f8a0455d374 100644
--- a/system/stack/mmc/proto/mmc_config.proto
+++ b/system/stack/mmc/proto/mmc_config.proto
@@ -23,7 +23,7 @@ option optimize_for = LITE_RUNTIME;
 // union of Lc3 config and codec parameters
 message Lc3Param {
   // encoder/decoder config
-  int32 dt_hz = 1;
+  int32 dt_us = 1;
   int32 sr_hz = 2;
   int32 sr_pcm_hz = 3;
 
diff --git a/system/stack/mmc/proto/mmc_service.proto b/system/stack/mmc/proto/mmc_service.proto
new file mode 100644
index 0000000000000000000000000000000000000000..c7819b80834fde53336d63f8cc8ab695dcc5a062
--- /dev/null
+++ b/system/stack/mmc/proto/mmc_service.proto
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+syntax = "proto3";
+
+package mmc;
+
+import "mmc_config.proto";
+
+option optimize_for = LITE_RUNTIME;
+
+message CodecInitRequest {
+  // Codec-specific parameters passed by client.
+  ConfigParam config = 1;
+}
+
+message CodecInitResponse {
+  // Socket name generated by the daemon.
+  string socket_token = 1;
+  // Input frame size accepted by the codec server.
+  int32 input_frame_size = 2;
+}