diff --git a/audio/aidl/Android.bp b/audio/aidl/Android.bp
index 40aa229..4e50b7a 100644
--- a/audio/aidl/Android.bp
+++ b/audio/aidl/Android.bp
@@ -156,6 +156,7 @@
         "android/hardware/audio/effect/IEffect.aidl",
         "android/hardware/audio/effect/IFactory.aidl",
         "android/hardware/audio/effect/Parameter.aidl",
+        "android/hardware/audio/effect/Processing.aidl",
         "android/hardware/audio/effect/State.aidl",
     ],
     imports: [
diff --git a/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/Descriptor.aidl b/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/Descriptor.aidl
index 1c86cf3..07b25f8 100644
--- a/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/Descriptor.aidl
+++ b/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/Descriptor.aidl
@@ -53,10 +53,11 @@
   parcelable Identity {
     android.media.audio.common.AudioUuid type;
     android.media.audio.common.AudioUuid uuid;
+    @nullable android.media.audio.common.AudioUuid proxy;
+    android.hardware.audio.effect.Flags flags;
   }
   @VintfStability
   parcelable Common {
     android.hardware.audio.effect.Descriptor.Identity id;
-    android.hardware.audio.effect.Flags flags;
   }
 }
diff --git a/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/IFactory.aidl b/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/IFactory.aidl
index db06475..a22c591 100644
--- a/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/IFactory.aidl
+++ b/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/IFactory.aidl
@@ -35,6 +35,7 @@
 @VintfStability
 interface IFactory {
   android.hardware.audio.effect.Descriptor.Identity[] queryEffects(in @nullable android.media.audio.common.AudioUuid type, in @nullable android.media.audio.common.AudioUuid implementation);
+  android.hardware.audio.effect.Processing[] queryProcessing(in @nullable android.hardware.audio.effect.Processing.Type type);
   android.hardware.audio.effect.IEffect createEffect(in android.media.audio.common.AudioUuid implUuid);
   void destroyEffect(in android.hardware.audio.effect.IEffect handle);
 }
diff --git a/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/Processing.aidl b/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/Processing.aidl
new file mode 100644
index 0000000..a779ae4
--- /dev/null
+++ b/audio/aidl/aidl_api/android.hardware.audio.effect/current/android/hardware/audio/effect/Processing.aidl
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.audio.effect;
+@VintfStability
+parcelable Processing {
+  android.hardware.audio.effect.Processing.Type type;
+  android.hardware.audio.effect.Descriptor.Identity[] ids;
+  @VintfStability
+  union Type {
+    android.media.audio.common.AudioStreamType streamType = android.media.audio.common.AudioStreamType.INVALID;
+    android.media.audio.common.AudioSource source;
+  }
+}
diff --git a/audio/aidl/android/hardware/audio/effect/Descriptor.aidl b/audio/aidl/android/hardware/audio/effect/Descriptor.aidl
index aca9bbe..9c18f2e 100644
--- a/audio/aidl/android/hardware/audio/effect/Descriptor.aidl
+++ b/audio/aidl/android/hardware/audio/effect/Descriptor.aidl
@@ -23,6 +23,13 @@
 /**
  * Descriptor contains all information (capabilities, attributes, etc) for an effect implementation.
  * The client uses this information to decide when and how to apply an effect implementation.
+ *
+ * Each type of effect can have more than one implementation (differentiated by implementation
+ * UUID), the effect proxy act as a combination of two implementations (usually one software and
+ * one offload implementation), so effect processing can be seamlessly switched between
+ * implementations in same proxy depending on the configuration and/or use case. If the optional
+ * proxy UUID is specified in Descriptor.Identity, then client must consider the effect instance as
+ * part of the effect proxy.
  */
 @VintfStability
 parcelable Descriptor {
@@ -69,6 +76,15 @@
          * UUID for this particular implementation.
          */
         AudioUuid uuid;
+        /**
+         * Optional proxy UUID. This field must be set to the proxy effect type UUID if the effect
+         * implementation is part of a proxy effect.
+         */
+        @nullable AudioUuid proxy;
+        /**
+         * Capability flags defined for the effect implementation.
+         */
+        Flags flags;
     }
 
     // Common attributes of all effect implementation.
@@ -78,10 +94,6 @@
          * Identity of effect implementation.
          */
         Identity id;
-        /**
-         * Effect engine defined capabilities/requirements flags.
-         */
-        Flags flags;
     }
     Common common;
 
diff --git a/audio/aidl/android/hardware/audio/effect/IFactory.aidl b/audio/aidl/android/hardware/audio/effect/IFactory.aidl
index 4873d3a..db26e61 100644
--- a/audio/aidl/android/hardware/audio/effect/IFactory.aidl
+++ b/audio/aidl/android/hardware/audio/effect/IFactory.aidl
@@ -18,6 +18,7 @@
 
 import android.hardware.audio.effect.Descriptor;
 import android.hardware.audio.effect.IEffect;
+import android.hardware.audio.effect.Processing;
 import android.media.audio.common.AudioUuid;
 
 /**
@@ -45,6 +46,16 @@
             in @nullable AudioUuid type, in @nullable AudioUuid implementation);
 
     /**
+     * Return a list of defined processings, with the optional filter by Processing type.
+     * An effect can exist more than once in the returned list, which means this effect must be used
+     * in more than one processing type.
+     *
+     * @param type Type of processing to query, can be AudioStreamType or AudioSource.
+     * @return list of processing defined with the optional filter by Processing.Type.
+     */
+    Processing[] queryProcessing(in @nullable Processing.Type type);
+
+    /**
      * Called by the audio framework to create the effect (identified by the implementation UUID
      * parameter).
      *
diff --git a/audio/aidl/android/hardware/audio/effect/Processing.aidl b/audio/aidl/android/hardware/audio/effect/Processing.aidl
new file mode 100644
index 0000000..ef32e8c
--- /dev/null
+++ b/audio/aidl/android/hardware/audio/effect/Processing.aidl
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+package android.hardware.audio.effect;
+
+import android.hardware.audio.effect.Descriptor;
+import android.media.audio.common.AudioSource;
+import android.media.audio.common.AudioStreamType;
+import android.media.audio.common.AudioUuid;
+
+/**
+ * List of effects which must be used for certain pre-processing or post-processing.
+ */
+@VintfStability
+parcelable Processing {
+    @VintfStability
+    union Type {
+        AudioStreamType streamType = AudioStreamType.INVALID;
+        AudioSource source;
+    }
+
+    /**
+     * Specifies the type of processing by referring to the output stream type (AudioStreamType) or
+     * the input stream source (AudioSource).
+     */
+    Type type;
+    /**
+     * List of effect identities for this processing.
+     */
+    Descriptor.Identity[] ids;
+}
diff --git a/audio/aidl/default/EffectFactory.cpp b/audio/aidl/default/EffectFactory.cpp
index 4877956..8e107a2 100644
--- a/audio/aidl/default/EffectFactory.cpp
+++ b/audio/aidl/default/EffectFactory.cpp
@@ -73,6 +73,17 @@
     return ndk::ScopedAStatus::ok();
 }
 
+ndk::ScopedAStatus Factory::queryProcessing(const std::optional<Processing::Type>& in_type,
+                                            std::vector<Processing>* _aidl_return) {
+    // TODO: implement this with audio_effect.xml.
+    if (in_type.has_value()) {
+        // return all matching process filter
+        LOG(DEBUG) << __func__ << " process type: " << in_type.value().toString();
+    }
+    LOG(DEBUG) << __func__ << " return " << _aidl_return->size();
+    return ndk::ScopedAStatus::ok();
+}
+
 #define RETURN_IF_BINDER_EXCEPTION(functor)                                 \
     {                                                                       \
         binder_exception_t exception = functor;                             \
diff --git a/audio/aidl/default/include/effectFactory-impl/EffectFactory.h b/audio/aidl/default/include/effectFactory-impl/EffectFactory.h
index d373048..6195d8a 100644
--- a/audio/aidl/default/include/effectFactory-impl/EffectFactory.h
+++ b/audio/aidl/default/include/effectFactory-impl/EffectFactory.h
@@ -43,6 +43,16 @@
             std::vector<Descriptor::Identity>* out_descriptor) override;
 
     /**
+     * @brief Query list of defined processing, with the optional filter by AudioStreamType
+     *
+     * @param in_type Type of processing, could be AudioStreamType or AudioSource. Optional.
+     * @param _aidl_return List of processing filtered by in_type.
+     * @return ndk::ScopedAStatus
+     */
+    ndk::ScopedAStatus queryProcessing(const std::optional<Processing::Type>& in_type,
+                                       std::vector<Processing>* _aidl_return) override;
+
+    /**
      * @brief Create an effect instance for a certain implementation (identified by UUID).
      *
      * @param in_impl_uuid Effect implementation UUID.
diff --git a/audio/aidl/vts/EffectFactoryHelper.h b/audio/aidl/vts/EffectFactoryHelper.h
index 3cbca45..cf94e58 100644
--- a/audio/aidl/vts/EffectFactoryHelper.h
+++ b/audio/aidl/vts/EffectFactoryHelper.h
@@ -31,6 +31,7 @@
 using aidl::android::hardware::audio::effect::IEffect;
 using aidl::android::hardware::audio::effect::IFactory;
 using aidl::android::hardware::audio::effect::Parameter;
+using aidl::android::hardware::audio::effect::Processing;
 using aidl::android::media::audio::common::AudioUuid;
 
 class EffectFactoryHelper {
@@ -57,6 +58,16 @@
         mIds = *_aidl_return;
     }
 
+    void QueryProcessing(const std::optional<Processing::Type>& in_type,
+                         std::vector<Processing>* _aidl_return) {
+        ASSERT_NE(mEffectFactory, nullptr);
+        EXPECT_IS_OK(mEffectFactory->queryProcessing(in_type, _aidl_return));
+        // only update the whole list if no filter applied
+        if (!in_type.has_value()) {
+            mProcesses = *_aidl_return;
+        }
+    }
+
     void CreateEffects() {
         ASSERT_NE(mEffectFactory, nullptr);
         for (const auto& id : mIds) {
@@ -127,6 +138,7 @@
     AudioHalBinderServiceUtil binderUtil;
     std::vector<Descriptor::Identity> mIds;
     std::vector<Descriptor::Identity> mCompleteIds;
+    std::vector<Processing> mProcesses;
 
     std::map<std::shared_ptr<IEffect>, Descriptor::Identity> mEffectIdMap;
 };
diff --git a/audio/aidl/vts/VtsHalAudioEffectFactoryTargetTest.cpp b/audio/aidl/vts/VtsHalAudioEffectFactoryTargetTest.cpp
index dd17a6f..454ce29 100644
--- a/audio/aidl/vts/VtsHalAudioEffectFactoryTargetTest.cpp
+++ b/audio/aidl/vts/VtsHalAudioEffectFactoryTargetTest.cpp
@@ -38,6 +38,7 @@
 
 using aidl::android::hardware::audio::effect::Descriptor;
 using aidl::android::hardware::audio::effect::IFactory;
+using aidl::android::hardware::audio::effect::Processing;
 using aidl::android::media::audio::common::AudioUuid;
 
 /// Effect factory testing.
@@ -222,6 +223,12 @@
     EXPECT_EQ(effectMap.size(), 0UL);
 }
 
+TEST_P(EffectFactoryTest, QueryProcess) {
+    std::vector<Processing> processing;
+    mFactory.QueryProcessing(std::nullopt, &processing);
+    // TODO: verify the number of process in example implementation after audio_effects.xml migrated
+}
+
 INSTANTIATE_TEST_SUITE_P(EffectFactoryTest, EffectFactoryTest,
                          testing::ValuesIn(android::getAidlHalInstanceNames(IFactory::descriptor)),
                          android::PrintInstanceNameToString);