diff --git a/C2VDAComponent.cpp b/C2VDAComponent.cpp
index 2b3abde..2e8f9d3 100644
--- a/C2VDAComponent.cpp
+++ b/C2VDAComponent.cpp
@@ -12,11 +12,14 @@
 #endif
 
 #define __C2_GENERATE_GLOBAL_VARS__
+#include <C2VDAAllocatorStore.h>
+#include <C2VdaBqBlockPool.h>
 #include <C2VDAComponent.h>
 #include <C2VDASupport.h>  // to getParamReflector from vda store
 
 #include <videodev2.h>
 
+#include <C2AllocatorGralloc.h>
 #include <C2ComponentFactory.h>
 #include <C2PlatformSupport.h>
 
@@ -52,6 +55,9 @@
 const C2String kVP8DecoderName = "c2.vda.vp8.decoder";
 const C2String kVP9DecoderName = "c2.vda.vp9.decoder";
 
+const uint32_t kDpbOutputBufferExtraCount = 3;  // Use the same number as ACodec.
+const int kDequeueRetryDelayUs = 10000;  // Wait time of dequeue buffer retry in microseconds.
+
 }  // namespace
 
 C2VDAComponent::IntfImpl::IntfImpl(C2String name, const std::shared_ptr<C2ReflectorHelper>& helper)
@@ -170,28 +176,6 @@
         CHECK_NE(mComponentState, ComponentState::UNINITIALIZED); \
     } while (0)
 
-class C2VDAGraphicBuffer : public C2Buffer {
-public:
-    C2VDAGraphicBuffer(const std::shared_ptr<C2GraphicBlock>& block, const media::Rect& visibleRect,
-                       const base::Closure& releaseCB);
-    ~C2VDAGraphicBuffer() override;
-
-private:
-    base::Closure mReleaseCB;
-};
-
-C2VDAGraphicBuffer::C2VDAGraphicBuffer(const std::shared_ptr<C2GraphicBlock>& block,
-                                       const media::Rect& visibleRect,
-                                       const base::Closure& releaseCB)
-      : C2Buffer({block->share(C2Rect(visibleRect.width(), visibleRect.height()), C2Fence())}),
-        mReleaseCB(releaseCB) {}
-
-C2VDAGraphicBuffer::~C2VDAGraphicBuffer() {
-    if (!mReleaseCB.is_null()) {
-        mReleaseCB.Run();
-    }
-}
-
 C2VDAComponent::VideoFormat::VideoFormat(HalPixelFormat pixelFormat, uint32_t minNumBuffers,
                                          media::Size codedSize, media::Rect visibleRect)
       : mPixelFormat(pixelFormat),
@@ -199,11 +183,22 @@
         mCodedSize(codedSize),
         mVisibleRect(visibleRect) {}
 
+static uint32_t getSlotFromGraphicBlockHandle(const C2Handle* const handle) {
+    uint32_t width, height, format, stride, igbp_slot, generation;
+    uint64_t usage, igbp_id;
+    _UnwrapNativeCodec2GrallocMetadata(
+            handle, &width, &height, &format, &usage, &stride, &generation, &igbp_id, &igbp_slot);
+    ALOGV("Unwrap Metadata: igbp[%" PRIu64 ", %u] (%u*%u, fmt %#x, usage %" PRIx64 ", stride %u)",
+          igbp_id, igbp_slot, width, height, format, usage, stride);
+    return igbp_slot;
+}
+
 C2VDAComponent::C2VDAComponent(C2String name, c2_node_id_t id,
                                const std::shared_ptr<C2ReflectorHelper>& helper)
       : mIntfImpl(std::make_shared<IntfImpl>(name, helper)),
         mIntf(std::make_shared<SimpleInterface<IntfImpl>>(name.c_str(), id, mIntfImpl)),
         mThread("C2VDAComponentThread"),
+        mDequeueThread("C2VDAComponentDequeueThread"),
         mVDAInitResult(VideoDecodeAcceleratorAdaptor::Result::ILLEGAL_STATE),
         mComponentState(ComponentState::UNINITIALIZED),
         mDrainWithEOS(false),
@@ -241,6 +236,7 @@
         mVDAAdaptor->destroy();
         mVDAAdaptor.reset(nullptr);
     }
+    stopDequeueThread();
 }
 
 void C2VDAComponent::onStart(media::VideoCodecProfile profile, base::WaitableEvent* done) {
@@ -351,16 +347,9 @@
     reportFinishedWorkIfAny();
 }
 
-// This is used as callback while output buffer is released by client.
-// TODO(johnylin): consider to use C2Buffer::registerOnDestroyNotify instead
-void C2VDAComponent::returnOutputBuffer(int32_t pictureBufferId) {
-    mTaskRunner->PostTask(FROM_HERE, base::Bind(&C2VDAComponent::onOutputBufferReturned,
-                                                base::Unretained(this), pictureBufferId));
-}
-
-void C2VDAComponent::onOutputBufferReturned(int32_t pictureBufferId) {
+void C2VDAComponent::onOutputBufferReturned(uint32_t slotId) {
     DCHECK(mTaskRunner->BelongsToCurrentThread());
-    ALOGV("onOutputBufferReturned: picture id=%d", pictureBufferId);
+    ALOGV("onOutputBufferReturned: slot id=%u", slotId);
     if (mComponentState == ComponentState::UNINITIALIZED) {
         // Output buffer is returned from client after component is stopped. Just let the buffer be
         // released.
@@ -369,7 +358,7 @@
 
     // TODO(johnylin): when buffer is returned, we should confirm that output format is not changed
     //                 yet. If changed, just let the buffer be released.
-    GraphicBlockInfo* info = getGraphicBlockById(pictureBufferId);
+    GraphicBlockInfo* info = getGraphicBlockBySlot(slotId);
     if (!info) {
         reportError(C2_CORRUPTED);
         return;
@@ -402,12 +391,14 @@
     CHECK_EQ(info->mState, GraphicBlockInfo::State::OWNED_BY_ACCELERATOR);
     // Output buffer will be passed to client soon along with mListener->onWorkDone_nb().
     info->mState = GraphicBlockInfo::State::OWNED_BY_CLIENT;
+    mBuffersInClient++;
 
     // Attach output buffer to the work corresponded to bitstreamId.
-    work->worklets.front()->output.buffers.emplace_back(std::make_shared<C2VDAGraphicBuffer>(
-            info->mGraphicBlock, mOutputFormat.mVisibleRect,
-            base::Bind(&C2VDAComponent::returnOutputBuffer, mWeakThisFactory.GetWeakPtr(),
-                       pictureBufferId)));
+    auto block = info->mGraphicBlock;
+    work->worklets.front()->output.buffers.emplace_back(C2Buffer::CreateGraphicBuffer(
+            block->share(C2Rect(mOutputFormat.mVisibleRect.width(),
+                                mOutputFormat.mVisibleRect.height()),
+                         C2Fence())));
 
     // TODO: this does not work for timestamps as they can wrap around
     int64_t currentTimestamp = base::checked_cast<int64_t>(work->input.ordinal.timestamp.peek());
@@ -552,6 +543,8 @@
 
     mGraphicBlocks.clear();
 
+    stopDequeueThread();
+
     mStopDoneEvent->Signal();
     mStopDoneEvent = nullptr;
     mComponentState = ComponentState::UNINITIALIZED;
@@ -606,6 +599,19 @@
     return &mGraphicBlocks[blockId];
 }
 
+C2VDAComponent::GraphicBlockInfo* C2VDAComponent::getGraphicBlockBySlot(uint32_t slotId) {
+    auto blockIter = std::find_if(mGraphicBlocks.begin(), mGraphicBlocks.end(),
+                                  [slotId](const GraphicBlockInfo& gb) {
+                                      return gb.mSlotId == slotId;
+                                  });
+
+    if (blockIter == mGraphicBlocks.end()) {
+        ALOGE("getGraphicBlockBySlot failed: slot=%u", slotId);
+        return nullptr;
+    }
+    return &(*blockIter);
+}
+
 void C2VDAComponent::onOutputFormatChanged(std::unique_ptr<VideoFormat> format) {
     DCHECK(mTaskRunner->BelongsToCurrentThread());
     ALOGV("onOutputFormatChanged");
@@ -684,7 +690,25 @@
         }
     }
 
+    stopDequeueThread();
     mGraphicBlocks.clear();
+
+    // Set requested buffer count to C2VdaBqBlockPool.
+    std::shared_ptr<C2VdaBqBlockPool> bqPool =
+            std::static_pointer_cast<C2VdaBqBlockPool>(mOutputBlockPool);
+    if (bqPool) {
+        err = bqPool->requestNewBufferSet(static_cast<uint32_t>(bufferCount));
+        if (err != C2_OK) {
+            ALOGE("failed to set buffer count magic to block pool: %d", err);
+            reportError(err);
+            return err;
+        }
+    } else {
+        ALOGE("Component only supports C2VdaBqBlockPool");
+        reportError(C2_CORRUPTED);
+        return C2_CORRUPTED;
+    }
+
     for (size_t i = 0; i < bufferCount; ++i) {
         std::shared_ptr<C2GraphicBlock> block;
         C2MemoryUsage usage = {C2MemoryUsage::CPU_READ, 0};
@@ -699,6 +723,11 @@
         appendOutputBuffer(std::move(block));
     }
     mOutputFormat.mMinNumBuffers = bufferCount;
+
+    if (!startDequeueThread(size, pixelFormat)) {
+        reportError(C2_CORRUPTED);
+        return C2_CORRUPTED;
+    }
     return C2_OK;
 }
 
@@ -766,6 +795,8 @@
     info.mHandle = std::move(passedHandle);
     info.mPlanes = std::move(passedPlanes);
 
+    info.mSlotId = getSlotFromGraphicBlockHandle(info.mGraphicBlock->handle());
+
     mGraphicBlocks.push_back(std::move(info));
 }
 
@@ -1070,6 +1101,56 @@
     mListener->onError_nb(shared_from_this(), static_cast<uint32_t>(error));
 }
 
+bool C2VDAComponent::startDequeueThread(const media::Size& size, uint32_t pixelFormat) {
+    CHECK(!mDequeueThread.IsRunning());
+    if (!mDequeueThread.Start()) {
+        ALOGE("failed to start dequeue thread!!");
+        return false;
+    }
+    mDequeueLoopStop.store(false);
+    mBuffersInClient.store(0u);
+    mDequeueThread.task_runner()->PostTask(
+            FROM_HERE, base::Bind(&C2VDAComponent::dequeueThreadLoop, base::Unretained(this),
+                                  size, pixelFormat));
+    return true;
+}
+
+void C2VDAComponent::stopDequeueThread() {
+    if (mDequeueThread.IsRunning()) {
+        mDequeueLoopStop.store(true);
+        mDequeueThread.Stop();
+    }
+}
+
+void C2VDAComponent::dequeueThreadLoop(const media::Size& size, uint32_t pixelFormat) {
+    ALOGV("dequeueThreadLoop starts");
+    DCHECK(mDequeueThread.task_runner()->BelongsToCurrentThread());
+
+    while (!mDequeueLoopStop.load()) {
+        if (mBuffersInClient.load() == 0) {
+            ::usleep(kDequeueRetryDelayUs);  // wait for retry
+            continue;
+        }
+        std::shared_ptr<C2GraphicBlock> block;
+        C2MemoryUsage usage = {C2MemoryUsage::CPU_READ, 0};
+        auto err = mOutputBlockPool->fetchGraphicBlock(size.width(), size.height(), pixelFormat,
+                                                       usage, &block);
+        if (err == C2_TIMED_OUT) {
+            continue;  // wait for retry
+        }
+        if (err == C2_OK) {
+            auto slot = getSlotFromGraphicBlockHandle(block->handle());
+            mTaskRunner->PostTask(FROM_HERE, base::Bind(&C2VDAComponent::onOutputBufferReturned,
+                                                        base::Unretained(this), slot));
+            mBuffersInClient--;
+        } else {
+            ALOGE("dequeueThreadLoop got error: %d", err);
+            break;
+        }
+    }
+    ALOGV("dequeueThreadLoop terminates");
+}
+
 class C2VDAComponentFactory : public C2ComponentFactory {
 public:
     C2VDAComponentFactory(C2String decoderName)