diff --git a/media/libmediatranscoding/TranscoderWrapper.cpp b/media/libmediatranscoding/TranscoderWrapper.cpp
new file mode 100644
index 0000000..86cb86a
--- /dev/null
+++ b/media/libmediatranscoding/TranscoderWrapper.cpp
@@ -0,0 +1,346 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "TranscoderWrapper"
+
+#include <aidl/android/media/TranscodingErrorCode.h>
+#include <aidl/android/media/TranscodingRequestParcel.h>
+#include <media/MediaTranscoder.h>
+#include <media/NdkCommon.h>
+#include <media/TranscoderWrapper.h>
+#include <utils/Log.h>
+
+#include <thread>
+
+namespace android {
+using Status = ::ndk::ScopedAStatus;
+using ::aidl::android::media::TranscodingErrorCode;
+using ::aidl::android::media::TranscodingVideoCodecType;
+using ::aidl::android::media::TranscodingVideoTrackFormat;
+
+static TranscodingErrorCode toTranscodingError(media_status_t status) {
+    switch (status) {
+    case AMEDIA_OK:
+        return TranscodingErrorCode::kNoError;
+    case AMEDIACODEC_ERROR_INSUFFICIENT_RESOURCE:  // FALLTHRU
+    case AMEDIACODEC_ERROR_RECLAIMED:
+        return TranscodingErrorCode::kInsufficientResources;
+    case AMEDIA_ERROR_MALFORMED:
+        return TranscodingErrorCode::kMalformed;
+    case AMEDIA_ERROR_UNSUPPORTED:
+        return TranscodingErrorCode::kUnsupported;
+    case AMEDIA_ERROR_INVALID_OBJECT:  // FALLTHRU
+    case AMEDIA_ERROR_INVALID_PARAMETER:
+        return TranscodingErrorCode::kInvalidParameter;
+    case AMEDIA_ERROR_INVALID_OPERATION:
+        return TranscodingErrorCode::kInvalidOperation;
+    case AMEDIA_ERROR_IO:
+        return TranscodingErrorCode::kErrorIO;
+    case AMEDIA_ERROR_UNKNOWN:  // FALLTHRU
+    default:
+        return TranscodingErrorCode::kUnknown;
+    }
+}
+
+//static
+const char* TranscoderWrapper::toString(Event::Type type) {
+    switch (type) {
+    case Event::Start:
+        return "Start";
+    case Event::Pause:
+        return "Pause";
+    case Event::Resume:
+        return "Resume";
+    case Event::Stop:
+        return "Stop";
+    case Event::Finish:
+        return "Finish";
+    case Event::Error:
+        return "Error";
+    default:
+        break;
+    }
+    return "(unknown)";
+}
+
+class TranscoderWrapper::CallbackImpl : public MediaTranscoder::CallbackInterface {
+public:
+    CallbackImpl(const std::shared_ptr<TranscoderWrapper>& owner, ClientIdType clientId,
+                 JobIdType jobId)
+          : mOwner(owner), mClientId(clientId), mJobId(jobId) {}
+
+    virtual void onFinished(const MediaTranscoder* transcoder __unused) override {
+        auto owner = mOwner.lock();
+        if (owner != nullptr) {
+            owner->onFinish(mClientId, mJobId);
+        }
+    }
+
+    virtual void onError(const MediaTranscoder* transcoder __unused,
+                         media_status_t error) override {
+        auto owner = mOwner.lock();
+        if (owner != nullptr) {
+            owner->onError(mClientId, mJobId, toTranscodingError(error));
+        }
+    }
+
+    virtual void onProgressUpdate(const MediaTranscoder* transcoder __unused,
+                                  int32_t progress) override {
+        ALOGV("%s: job {%lld, %d}, progress %d", __FUNCTION__, (long long)mClientId, mJobId,
+              progress);
+    }
+
+    virtual void onCodecResourceLost(const MediaTranscoder* transcoder __unused,
+                                     const std::shared_ptr<const Parcelable>& pausedState
+                                             __unused) override {
+        ALOGV("%s: job {%lld, %d}", __FUNCTION__, (long long)mClientId, mJobId);
+    }
+
+private:
+    std::weak_ptr<TranscoderWrapper> mOwner;
+    ClientIdType mClientId;
+    JobIdType mJobId;
+};
+
+TranscoderWrapper::TranscoderWrapper() : mCurrentClientId(0), mCurrentJobId(-1) {
+    std::thread(&TranscoderWrapper::threadLoop, this).detach();
+}
+
+void TranscoderWrapper::setCallback(const std::shared_ptr<TranscoderCallbackInterface>& cb) {
+    mCallback = cb;
+}
+
+void TranscoderWrapper::start(ClientIdType clientId, JobIdType jobId,
+                              const TranscodingRequestParcel& request,
+                              const std::shared_ptr<ITranscodingClientCallback>& callback) {
+    queueEvent(Event::Start, clientId, jobId, [=] {
+        TranscodingErrorCode err = handleStart(clientId, jobId, request, callback);
+
+        if (err != TranscodingErrorCode::kNoError) {
+            cleanup();
+
+            auto callback = mCallback.lock();
+            if (callback != nullptr) {
+                callback->onError(clientId, jobId, err);
+            }
+        }
+    });
+}
+
+void TranscoderWrapper::pause(ClientIdType clientId, JobIdType jobId) {
+    queueEvent(Event::Pause, clientId, jobId, [] {});
+}
+
+void TranscoderWrapper::resume(ClientIdType clientId, JobIdType jobId) {
+    queueEvent(Event::Resume, clientId, jobId, [] {});
+}
+
+void TranscoderWrapper::stop(ClientIdType clientId, JobIdType jobId) {
+    queueEvent(Event::Stop, clientId, jobId, [=] {
+        if (clientId != mCurrentClientId || jobId != mCurrentJobId) {
+            ALOGW("Stopping job {%lld, %d} that's not current job {%lld, %d}", (long long)clientId,
+                  jobId, (long long)mCurrentClientId, mCurrentJobId);
+        }
+
+        // stop transcoder.
+        media_status_t err = mTranscoder->cancel();
+        if (err != AMEDIA_OK) {
+            ALOGE("failed to stop transcoder: %d", err);
+        } else {
+            ALOGI("transcoder stopped");
+        }
+
+        cleanup();
+    });
+}
+
+void TranscoderWrapper::onFinish(ClientIdType clientId, JobIdType jobId) {
+    queueEvent(Event::Finish, clientId, jobId, [=] {
+        cleanup();
+
+        auto callback = mCallback.lock();
+        if (callback != nullptr) {
+            callback->onFinish(clientId, jobId);
+        }
+    });
+}
+
+void TranscoderWrapper::onError(ClientIdType clientId, JobIdType jobId,
+                                TranscodingErrorCode error) {
+    queueEvent(Event::Error, clientId, jobId, [=] {
+        cleanup();
+
+        auto callback = mCallback.lock();
+        if (callback != nullptr) {
+            callback->onError(clientId, jobId, error);
+        }
+    });
+}
+
+static AMediaFormat* getVideoFormat(
+        const char* originalMime,
+        const std::optional<TranscodingVideoTrackFormat>& requestedFormat) {
+    if (requestedFormat == std::nullopt) {
+        return nullptr;
+    }
+
+    AMediaFormat* format = AMediaFormat_new();
+    bool changed = false;
+    if (requestedFormat->codecType == TranscodingVideoCodecType::kHevc
+            && strcmp(originalMime, AMEDIA_MIMETYPE_VIDEO_HEVC)) {
+        AMediaFormat_setString(format, AMEDIAFORMAT_KEY_MIME, AMEDIA_MIMETYPE_VIDEO_HEVC);
+        changed = true;
+    } else if (requestedFormat->codecType == TranscodingVideoCodecType::kAvc
+        && strcmp(originalMime, AMEDIA_MIMETYPE_VIDEO_AVC)) {
+        AMediaFormat_setString(format, AMEDIAFORMAT_KEY_MIME, AMEDIA_MIMETYPE_VIDEO_AVC);
+        changed = true;
+    }
+    if (requestedFormat->bitrateBps > 0) {
+        AMediaFormat_setInt32(format, AMEDIAFORMAT_KEY_BIT_RATE, requestedFormat->bitrateBps);
+        changed = true;
+    }
+    // TODO: translate other fields from requestedFormat to the format for MediaTranscoder.
+    // Also need to determine more settings to expose in TranscodingVideoTrackFormat.
+    if (!changed) {
+        AMediaFormat_delete(format);
+        // Use null format for passthru.
+        format = nullptr;
+    }
+    return format;
+}
+
+TranscodingErrorCode TranscoderWrapper::handleStart(
+        ClientIdType clientId, JobIdType jobId, const TranscodingRequestParcel& request,
+        const std::shared_ptr<ITranscodingClientCallback>& clientCb) {
+    if (clientCb == nullptr) {
+        ALOGE("client callback is null");
+        return TranscodingErrorCode::kInvalidParameter;
+    }
+
+    if (mTranscoder != nullptr) {
+        ALOGE("transcoder already running");
+        return TranscodingErrorCode::kInvalidOperation;
+    }
+
+    Status status;
+    ::ndk::ScopedFileDescriptor srcFd, dstFd;
+    status = clientCb->openFileDescriptor(request.sourceFilePath, "r", &srcFd);
+    if (!status.isOk() || srcFd.get() < 0) {
+        ALOGE("failed to open source");
+        return TranscodingErrorCode::kErrorIO;
+    }
+
+    status = clientCb->openFileDescriptor(request.destinationFilePath, "w", &dstFd);
+    if (!status.isOk() || dstFd.get() < 0) {
+        ALOGE("failed to open destination");
+        return TranscodingErrorCode::kErrorIO;
+    }
+
+    mCurrentClientId = clientId;
+    mCurrentJobId = jobId;
+    mTranscoderCb = std::make_shared<CallbackImpl>(shared_from_this(), clientId, jobId);
+    mTranscoder = MediaTranscoder::create(mTranscoderCb, nullptr);
+    if (mTranscoder == nullptr) {
+        ALOGE("failed to create transcoder");
+        return TranscodingErrorCode::kUnknown;
+    }
+
+    media_status_t err = mTranscoder->configureSource(srcFd.get());
+    if (err != AMEDIA_OK) {
+        ALOGE("failed to configure source: %d", err);
+        return toTranscodingError(err);
+    }
+
+    std::vector<std::shared_ptr<AMediaFormat>> trackFormats = mTranscoder->getTrackFormats();
+    if (trackFormats.size() == 0) {
+        ALOGE("failed to get track formats!");
+        return TranscodingErrorCode::kMalformed;
+    }
+
+    for (int i = 0; i < trackFormats.size(); ++i) {
+        AMediaFormat* format = nullptr;
+        const char* mime = nullptr;
+        AMediaFormat_getString(trackFormats[i].get(), AMEDIAFORMAT_KEY_MIME, &mime);
+
+        if (!strncmp(mime, "video/", 6)) {
+            format = getVideoFormat(mime, request.requestedVideoTrackFormat);
+        }
+
+        err = mTranscoder->configureTrackFormat(i, format);
+        if (format != nullptr) {
+            AMediaFormat_delete(format);
+        }
+        if (err != AMEDIA_OK) {
+            ALOGE("failed to configure track format for track %d: %d", i, err);
+            return toTranscodingError(err);
+        }
+    }
+
+    err = mTranscoder->configureDestination(dstFd.get());
+    if (err != AMEDIA_OK) {
+        ALOGE("failed to configure dest: %d", err);
+        return toTranscodingError(err);
+    }
+
+    err = mTranscoder->start();
+    if (err != AMEDIA_OK) {
+        ALOGE("failed to start transcoder: %d", err);
+        return toTranscodingError(err);
+    }
+
+    ALOGI("transcoder started");
+    return TranscodingErrorCode::kNoError;
+}
+
+void TranscoderWrapper::cleanup() {
+    mCurrentClientId = 0;
+    mCurrentJobId = -1;
+    mTranscoderCb = nullptr;
+    mTranscoder = nullptr;
+}
+
+void TranscoderWrapper::queueEvent(Event::Type type, ClientIdType clientId, JobIdType jobId,
+                                   const std::function<void()> runnable) {
+    ALOGV("%s: job {%lld, %d}: %s", __FUNCTION__, (long long)clientId, jobId, toString(type));
+
+    std::scoped_lock lock{mLock};
+
+    mQueue.push_back({type, clientId, jobId, runnable});
+    mCondition.notify_one();
+}
+
+void TranscoderWrapper::threadLoop() {
+    std::unique_lock<std::mutex> lock{mLock};
+    // TranscoderWrapper currently lives in the transcoding service, as long as
+    // MediaTranscodingService itself.
+    while (true) {
+        // Wait for the next event.
+        while (mQueue.empty()) {
+            mCondition.wait(lock);
+        }
+
+        Event event = *mQueue.begin();
+        mQueue.pop_front();
+
+        ALOGD("%s: job {%lld, %d}: %s", __FUNCTION__, (long long)event.clientId, event.jobId,
+              toString(event.type));
+
+        event.runnable();
+    }
+}
+
+}  // namespace android