diff --git a/runtime/conversation/model_data_processor/BUILD b/runtime/conversation/model_data_processor/BUILD
index ebf93ab5..1290f6d8 100644
--- a/runtime/conversation/model_data_processor/BUILD
+++ b/runtime/conversation/model_data_processor/BUILD
@@ -38,9 +38,9 @@ cc_library(
     srcs = ["data_utils.cc"],
     hdrs = ["data_utils.h"],
     deps = [
-        "@com_google_absl//absl/memory",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/strings",
         "@nlohmann_json//:json",
         "//runtime/util:memory_mapped_file",
     ],
@@ -99,14 +99,11 @@ cc_library(
         ":generic_data_processor",
         ":generic_data_processor_config",
         ":model_data_processor",
+        "@com_google_absl//absl/log:absl_log",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
-        "@com_google_absl//absl/strings:string_view",
-        "@nlohmann_json//:json",
         "//runtime/conversation:io_types",
-        "//runtime/engine:io_types",
         "//runtime/proto:llm_model_type_cc_proto",
-        "//runtime/util:litert_status_util",
     ],
 )
 
diff --git a/runtime/conversation/model_data_processor/data_utils.cc b/runtime/conversation/model_data_processor/data_utils.cc
index 6d046332..acd91183 100644
--- a/runtime/conversation/model_data_processor/data_utils.cc
+++ b/runtime/conversation/model_data_processor/data_utils.cc
@@ -19,6 +19,7 @@
 
 #include "absl/status/status.h"  // from @com_google_absl
 #include "absl/status/statusor.h"  // from @com_google_absl
+#include "absl/strings/escaping.h"  // from @com_google_absl
 #include "nlohmann/json.hpp"  // from @nlohmann_json
 #include "runtime/util/memory_mapped_file.h"
 
@@ -38,7 +39,12 @@ absl::StatusOr<std::unique_ptr<MemoryMappedFile>> LoadItemData(
       return MemoryMappedFile::Create(item["path"].get<std::string>());
     }
     if (item.contains("blob")) {
-      return InMemoryFile::Create(item["blob"]);
+      std::string blob_b64 = item["blob"].get<std::string>();
+      std::string blob;
+      if (!absl::Base64Unescape(blob_b64, &blob)) {
+        return absl::InvalidArgumentError("Failed to decode base64 blob.");
+      }
+      return InMemoryFile::Create(blob);
     }
     return absl::InvalidArgumentError(
         "Audio or image item must contain a path or blob.");
diff --git a/runtime/conversation/model_data_processor/data_utils.h b/runtime/conversation/model_data_processor/data_utils.h
index 202f286b..b460c445 100644
--- a/runtime/conversation/model_data_processor/data_utils.h
+++ b/runtime/conversation/model_data_processor/data_utils.h
@@ -38,7 +38,7 @@ namespace litert::lm {
 //  }
 //  {
 //    "type": "image",
-//    "blob": "raw image bytes as string",
+//    "blob": "base64 encoded image bytes as string",
 //  }
 //
 // 3. Audio item
@@ -48,7 +48,7 @@ namespace litert::lm {
 //  }
 //  {
 //    "type": "audio",
-//    "blob": "raw audio bytes as string",
+//    "blob": "base64 encoded audio bytes as string",
 //  }
 //
 // Note: though we support loading image and audio data from blob, this format
diff --git a/runtime/conversation/model_data_processor/data_utils_test.cc b/runtime/conversation/model_data_processor/data_utils_test.cc
index 4e049b54..6c5ed1c2 100644
--- a/runtime/conversation/model_data_processor/data_utils_test.cc
+++ b/runtime/conversation/model_data_processor/data_utils_test.cc
@@ -66,7 +66,7 @@ TEST(DataUtilsTest, LoadItemData_ImageItemWithBlob) {
   ASSERT_OK_AND_ASSIGN(std::unique_ptr<MemoryMappedFile> memory_mapped_file,
                        LoadItemData({
                            {"type", "image"},
-                           {"blob", "image_contents"},
+                           {"blob", "aW1hZ2VfY29udGVudHM="},
                        }));
   EXPECT_EQ(std::string(static_cast<const char*>(memory_mapped_file->data()),
                         memory_mapped_file->length()),
@@ -90,7 +90,7 @@ TEST(DataUtilsTest, LoadItemData_AudioItemWithBlob) {
   ASSERT_OK_AND_ASSIGN(std::unique_ptr<MemoryMappedFile> memory_mapped_file,
                        LoadItemData({
                            {"type", "audio"},
-                           {"blob", "audio_contents"},
+                           {"blob", "YXVkaW9fY29udGVudHM="},
                        }));
   EXPECT_EQ(std::string(static_cast<const char*>(memory_mapped_file->data()),
                         memory_mapped_file->length()),
@@ -120,5 +120,16 @@ TEST(DataUtilsTest, LoadItemData_InvalidItem) {
       testing::HasSubstr("Audio or image item must contain a path or blob."));
 }
 
+TEST(DataUtilsTest, LoadItemData_ImageItemWithInvalidBase64Blob) {
+  auto result = LoadItemData({
+      {"type", "image"},
+      {"blob", "invalid base64"},
+  });
+  EXPECT_THAT(result.status(),
+              testing::status::StatusIs(absl::StatusCode::kInvalidArgument));
+  EXPECT_THAT(result.status().message(),
+              testing::HasSubstr("Failed to decode base64 blob."));
+}
+
 }  // namespace
 }  // namespace litert::lm
diff --git a/runtime/conversation/model_data_processor/model_data_processor_factory.cc b/runtime/conversation/model_data_processor/model_data_processor_factory.cc
index 1590f4a2..e32c9b26 100644
--- a/runtime/conversation/model_data_processor/model_data_processor_factory.cc
+++ b/runtime/conversation/model_data_processor/model_data_processor_factory.cc
@@ -18,6 +18,7 @@
 #include <optional>
 #include <variant>
 
+#include "absl/log/absl_log.h"  // from @com_google_absl
 #include "absl/status/status.h"  // from @com_google_absl
 #include "absl/status/statusor.h"  // from @com_google_absl
 #include "runtime/conversation/io_types.h"
@@ -37,12 +38,16 @@ absl::StatusOr<std::unique_ptr<ModelDataProcessor>> CreateModelDataProcessor(
   switch (model_type.model_type_case()) {
     case proto::LlmModelType::kGemma3N:
     case proto::LlmModelType::kGemma3:
+      ABSL_LOG(INFO) << "Creating Gemma3DataProcessor for model type: "
+                     << model_type.model_type_case();
       return Gemma3DataProcessor::Create(
           std::holds_alternative<Gemma3DataProcessorConfig>(config)
               ? std::get<Gemma3DataProcessorConfig>(config)
               : Gemma3DataProcessorConfig(),
           preface);
     case proto::LlmModelType::kGenericModel: {
+      ABSL_LOG(INFO) << "Creating GenericDataProcessor for model type: "
+                     << model_type.model_type_case();
       if (std::holds_alternative<GenericDataProcessorConfig>(config)) {
         return GenericDataProcessor::Create(
             std::holds_alternative<GenericDataProcessorConfig>(config)