diff --git a/media/libaudiofoundation/AudioContainers.cpp b/media/libaudiofoundation/AudioContainers.cpp
index adc5d40..1bfe3f9 100644
--- a/media/libaudiofoundation/AudioContainers.cpp
+++ b/media/libaudiofoundation/AudioContainers.cpp
@@ -50,6 +50,10 @@
 }
 
 bool deviceTypesToString(const DeviceTypeSet &deviceTypes, std::string &str) {
+    if (deviceTypes.empty()) {
+        str = "Empty device types";
+        return true;
+    }
     bool ret = true;
     for (auto it = deviceTypes.begin(); it != deviceTypes.end();) {
         std::string deviceTypeStr;
@@ -83,4 +87,10 @@
     return ret;
 }
 
+std::string toString(const DeviceTypeSet& deviceTypes) {
+    std::string ret;
+    deviceTypesToString(deviceTypes, ret);
+    return ret;
+}
+
 } // namespace android