diff --git a/include/media/AudioIoDescriptor.h b/include/media/AudioIoDescriptor.h
new file mode 100644
index 0000000..2437901
--- /dev/null
+++ b/include/media/AudioIoDescriptor.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 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 ANDROID_AUDIO_IO_DESCRIPTOR_H
+#define ANDROID_AUDIO_IO_DESCRIPTOR_H
+
+namespace android {
+
+enum audio_io_config_event {
+    AUDIO_OUTPUT_OPENED,
+    AUDIO_OUTPUT_CLOSED,
+    AUDIO_OUTPUT_CONFIG_CHANGED,
+    AUDIO_INPUT_OPENED,
+    AUDIO_INPUT_CLOSED,
+    AUDIO_INPUT_CONFIG_CHANGED,
+};
+
+// audio input/output descriptor used to cache output configurations in client process to avoid
+// frequent calls through IAudioFlinger
+class AudioIoDescriptor : public RefBase {
+public:
+    AudioIoDescriptor() :
+        mSamplingRate(0), mFormat(AUDIO_FORMAT_DEFAULT), mChannelMask(AUDIO_CHANNEL_NONE),
+        mFrameCount(0), mLatency(0) {}
+
+    virtual ~AudioIoDescriptor() {}
+
+    audio_io_handle_t mIoHandle;
+    uint32_t mSamplingRate;
+    audio_format_t mFormat;
+    audio_channel_mask_t mChannelMask;
+    size_t mFrameCount;
+    uint32_t mLatency;
+};
+
+
+};  // namespace android
+
+#endif  /*ANDROID_AUDIO_IO_DESCRIPTOR_H*/
diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index a454481..8d3396d 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -19,6 +19,7 @@
 
 #include <hardware/audio_effect.h>
 #include <media/AudioPolicy.h>
+#include <media/AudioIoDescriptor.h>
 #include <media/IAudioFlingerClient.h>
 #include <media/IAudioPolicyServiceClient.h>
 #include <system/audio.h>
@@ -155,33 +156,6 @@
     // or no HW sync source is used.
     static audio_hw_sync_t getAudioHwSyncForSession(audio_session_t sessionId);
 
-    // types of io configuration change events received with ioConfigChanged()
-    enum io_config_event {
-        OUTPUT_OPENED,
-        OUTPUT_CLOSED,
-        OUTPUT_CONFIG_CHANGED,
-        INPUT_OPENED,
-        INPUT_CLOSED,
-        INPUT_CONFIG_CHANGED,
-        STREAM_CONFIG_CHANGED,
-        NUM_CONFIG_EVENTS
-    };
-
-    // audio output descriptor used to cache output configurations in client process to avoid
-    // frequent calls through IAudioFlinger
-    class OutputDescriptor {
-    public:
-        OutputDescriptor()
-        : samplingRate(0), format(AUDIO_FORMAT_DEFAULT), channelMask(0), frameCount(0), latency(0)
-            {}
-
-        uint32_t samplingRate;
-        audio_format_t format;
-        audio_channel_mask_t channelMask;
-        size_t frameCount;
-        uint32_t latency;
-    };
-
     // Events used to synchronize actions between audio sessions.
     // For instance SYNC_EVENT_PRESENTATION_COMPLETE can be used to delay recording start until
     // playback is complete on another audio session.
@@ -362,9 +336,16 @@
     class AudioFlingerClient: public IBinder::DeathRecipient, public BnAudioFlingerClient
     {
     public:
-        AudioFlingerClient() {
+        AudioFlingerClient() :
+            mInBuffSize(0), mInSamplingRate(0),
+            mInFormat(AUDIO_FORMAT_DEFAULT), mInChannelMask(AUDIO_CHANNEL_NONE) {
         }
 
+        void clearIoCache();
+        status_t getInputBufferSize(uint32_t sampleRate, audio_format_t format,
+                                    audio_channel_mask_t channelMask, size_t* buffSize);
+        sp<AudioIoDescriptor> getIoDescriptor(audio_io_handle_t ioHandle);
+
         // DeathRecipient
         virtual void binderDied(const wp<IBinder>& who);
 
@@ -372,7 +353,17 @@
 
         // indicate a change in the configuration of an output or input: keeps the cached
         // values for output/input parameters up-to-date in client process
-        virtual void ioConfigChanged(int event, audio_io_handle_t ioHandle, const void *param2);
+        virtual void ioConfigChanged(audio_io_config_event event,
+                                     const sp<AudioIoDescriptor>& ioDesc);
+    private:
+        Mutex                               mLock;
+        DefaultKeyedVector<audio_io_handle_t, sp<AudioIoDescriptor> > mIoDescriptors;
+
+        // cached values for recording getInputBufferSize() queries
+        size_t                              mInBuffSize;    // zero indicates cache is invalid
+        uint32_t                            mInSamplingRate;
+        audio_format_t                      mInFormat;
+        audio_channel_mask_t                mInChannelMask;
     };
 
     class AudioPolicyServiceClient: public IBinder::DeathRecipient,
@@ -404,8 +395,6 @@
     friend class AudioPolicyServiceClient;
 
     static Mutex gLock;      // protects gAudioFlinger and gAudioErrorCallback,
-    static Mutex gLockCache; // protects gOutputs, gPrevInSamplingRate, gPrevInFormat,
-                             // gPrevInChannelMask and gInBuffSize
     static Mutex gLockAPS;   // protects gAudioPolicyService and gAudioPolicyServiceClient
     static sp<IAudioFlinger> gAudioFlinger;
     static audio_error_callback gAudioErrorCallback;
@@ -417,10 +406,6 @@
     static audio_channel_mask_t gPrevInChannelMask;
 
     static sp<IAudioPolicyService> gAudioPolicyService;
-
-    // list of output descriptors containing cached parameters
-    // (sampling rate, framecount, channel count...)
-    static DefaultKeyedVector<audio_io_handle_t, OutputDescriptor *> gOutputs;
 };
 
 };  // namespace android
diff --git a/include/media/IAudioFlingerClient.h b/include/media/IAudioFlingerClient.h
index 75a9971..0080bc9 100644
--- a/include/media/IAudioFlingerClient.h
+++ b/include/media/IAudioFlingerClient.h
@@ -22,6 +22,7 @@
 #include <binder/IInterface.h>
 #include <utils/KeyedVector.h>
 #include <system/audio.h>
+#include <media/AudioIoDescriptor.h>
 
 namespace android {
 
@@ -33,7 +34,8 @@
     DECLARE_META_INTERFACE(AudioFlingerClient);
 
     // Notifies a change of audio input/output configuration.
-    virtual void ioConfigChanged(int event, audio_io_handle_t ioHandle, const void *param2) = 0;
+    virtual void ioConfigChanged(audio_io_config_event event,
+                                 const sp<AudioIoDescriptor>& ioDesc) = 0;
 
 };