diff --git a/media/libmediatranscoding/transcoder/Android.bp b/media/libmediatranscoding/transcoder/Android.bp
new file mode 100644
index 0000000..a8caebe
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/Android.bp
@@ -0,0 +1,48 @@
+/*
+ * 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.
+ */
+
+cc_library_shared {
+    name: "libmediatranscoder",
+
+    srcs: [
+        "MediaSampleReaderNDK.cpp",
+    ],
+
+    shared_libs: [
+        "libbase",
+        "libcutils",
+        "libmediandk",
+        "libutils",
+    ],
+
+    export_include_dirs: [
+        "include",
+    ],
+
+    cflags: [
+        "-Werror",
+        "-Wno-error=deprecated-declarations",
+        "-Wall",
+    ],
+
+    sanitize: {
+        misc_undefined: [
+            "unsigned-integer-overflow",
+            "signed-integer-overflow",
+        ],
+        cfi: true,
+    },
+}
diff --git a/media/libmediatranscoding/transcoder/MediaSampleReaderNDK.cpp b/media/libmediatranscoding/transcoder/MediaSampleReaderNDK.cpp
new file mode 100644
index 0000000..d0f117d
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/MediaSampleReaderNDK.cpp
@@ -0,0 +1,260 @@
+/*
+ * 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 "MediaSampleReader"
+
+#include <android-base/logging.h>
+#include <media/MediaSampleReaderNDK.h>
+
+#include <algorithm>
+#include <vector>
+
+namespace android {
+
+// static
+std::shared_ptr<MediaSampleReader> MediaSampleReaderNDK::createFromFd(int fd, size_t offset,
+                                                                      size_t size) {
+    AMediaExtractor* extractor = AMediaExtractor_new();
+    if (extractor == nullptr) {
+        LOG(ERROR) << "Unable to allocate AMediaExtractor";
+        return nullptr;
+    }
+
+    media_status_t status = AMediaExtractor_setDataSourceFd(extractor, fd, offset, size);
+    if (status != AMEDIA_OK) {
+        LOG(ERROR) << "AMediaExtractor_setDataSourceFd returned error: " << status;
+        AMediaExtractor_delete(extractor);
+        return nullptr;
+    }
+
+    auto sampleReader = std::shared_ptr<MediaSampleReaderNDK>(new MediaSampleReaderNDK(extractor));
+    status = sampleReader->init();
+    if (status != AMEDIA_OK) {
+        LOG(ERROR) << "MediaSampleReaderNDK::init returned error: " << status;
+        return nullptr;
+    }
+
+    return sampleReader;
+}
+
+MediaSampleReaderNDK::MediaSampleReaderNDK(AMediaExtractor* extractor)
+      : mExtractor(extractor), mTrackCount(AMediaExtractor_getTrackCount(mExtractor)) {
+    if (mTrackCount > 0) {
+        mTrackCursors.resize(mTrackCount);
+        mTrackCursors.resize(mTrackCount);
+    }
+}
+
+media_status_t MediaSampleReaderNDK::init() {
+    for (size_t trackIndex = 0; trackIndex < mTrackCount; trackIndex++) {
+        media_status_t status = AMediaExtractor_selectTrack(mExtractor, trackIndex);
+        if (status != AMEDIA_OK) {
+            LOG(ERROR) << "AMediaExtractor_selectTrack returned error: " << status;
+            return status;
+        }
+    }
+
+    mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);
+    if (mExtractorTrackIndex >= 0) {
+        mTrackCursors[mExtractorTrackIndex].current.set(mExtractorSampleIndex,
+                                                        AMediaExtractor_getSampleTime(mExtractor));
+    } else if (mTrackCount > 0) {
+        // The extractor track index is only allowed to be invalid if there are no tracks.
+        LOG(ERROR) << "Track index " << mExtractorTrackIndex << " is invalid for track count "
+                   << mTrackCount;
+        return AMEDIA_ERROR_MALFORMED;
+    }
+
+    return AMEDIA_OK;
+}
+
+MediaSampleReaderNDK::~MediaSampleReaderNDK() {
+    if (mExtractor != nullptr) {
+        AMediaExtractor_delete(mExtractor);
+    }
+}
+
+bool MediaSampleReaderNDK::advanceExtractor_l() {
+    // Reset the "next" sample time whenever the extractor advances past a sample that is current,
+    // to ensure that "next" is appropriately updated when the extractor advances over the next
+    // sample of that track.
+    if (mTrackCursors[mExtractorTrackIndex].current.isSet &&
+        mTrackCursors[mExtractorTrackIndex].current.index == mExtractorSampleIndex) {
+        mTrackCursors[mExtractorTrackIndex].next.reset();
+    }
+
+    if (!AMediaExtractor_advance(mExtractor)) {
+        return false;
+    }
+
+    mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);
+    mExtractorSampleIndex++;
+
+    SampleCursor& cursor = mTrackCursors[mExtractorTrackIndex];
+    if (mExtractorSampleIndex > cursor.previous.index) {
+        if (!cursor.current.isSet) {
+            cursor.current.set(mExtractorSampleIndex, AMediaExtractor_getSampleTime(mExtractor));
+        } else if (!cursor.next.isSet && mExtractorSampleIndex > cursor.current.index) {
+            cursor.next.set(mExtractorSampleIndex, AMediaExtractor_getSampleTime(mExtractor));
+        }
+    }
+    return true;
+}
+
+media_status_t MediaSampleReaderNDK::seekExtractorBackwards_l(int64_t targetTimeUs,
+                                                              int targetTrackIndex,
+                                                              uint64_t targetSampleIndex) {
+    if (targetSampleIndex > mExtractorSampleIndex) {
+        LOG(ERROR) << "Error: Forward seek is not supported";
+        return AMEDIA_ERROR_UNSUPPORTED;
+    }
+
+    // AMediaExtractor supports reading negative timestamps but does not support seeking to them.
+    const int64_t seekToTimeUs = std::max(targetTimeUs, (int64_t)0);
+    media_status_t status =
+            AMediaExtractor_seekTo(mExtractor, seekToTimeUs, AMEDIAEXTRACTOR_SEEK_PREVIOUS_SYNC);
+    if (status != AMEDIA_OK) {
+        LOG(ERROR) << "Unable to seek to " << seekToTimeUs << ", target " << targetTimeUs;
+        return status;
+    }
+    mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);
+    int64_t sampleTimeUs = AMediaExtractor_getSampleTime(mExtractor);
+
+    while (sampleTimeUs != targetTimeUs || mExtractorTrackIndex != targetTrackIndex) {
+        if (!AMediaExtractor_advance(mExtractor)) {
+            return AMEDIA_ERROR_END_OF_STREAM;
+        }
+        mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);
+        sampleTimeUs = AMediaExtractor_getSampleTime(mExtractor);
+    }
+    mExtractorSampleIndex = targetSampleIndex;
+    return AMEDIA_OK;
+}
+
+void MediaSampleReaderNDK::advanceTrack(int trackIndex) {
+    std::scoped_lock lock(mExtractorMutex);
+
+    if (trackIndex < 0 || trackIndex >= mTrackCount) {
+        LOG(ERROR) << "Invalid trackIndex " << trackIndex << " for trackCount " << mTrackCount;
+        return;
+    }
+
+    // Note: Positioning the extractor before advancing the track is needed for two reasons:
+    // 1. To enable multiple advances without explicitly letting the extractor catch up.
+    // 2. To prevent the extractor from being farther than "next".
+    (void)positionExtractorForTrack_l(trackIndex);
+
+    SampleCursor& cursor = mTrackCursors[trackIndex];
+    cursor.previous = cursor.current;
+    cursor.current = cursor.next;
+    cursor.next.reset();
+}
+
+media_status_t MediaSampleReaderNDK::positionExtractorForTrack_l(int trackIndex) {
+    media_status_t status = AMEDIA_OK;
+    const SampleCursor& cursor = mTrackCursors[trackIndex];
+
+    // Seek backwards if the extractor is ahead of the current time.
+    if (cursor.current.isSet && mExtractorSampleIndex > cursor.current.index) {
+        status = seekExtractorBackwards_l(cursor.current.timeStampUs, trackIndex,
+                                          cursor.current.index);
+        if (status != AMEDIA_OK) return status;
+    }
+
+    // Advance until extractor points to the current sample.
+    while (!(cursor.current.isSet && cursor.current.index == mExtractorSampleIndex)) {
+        if (!advanceExtractor_l()) {
+            return AMEDIA_ERROR_END_OF_STREAM;
+        }
+    }
+
+    return AMEDIA_OK;
+}
+
+media_status_t MediaSampleReaderNDK::getSampleInfoForTrack(int trackIndex, MediaSampleInfo* info) {
+    std::scoped_lock lock(mExtractorMutex);
+
+    if (trackIndex < 0 || trackIndex >= mTrackCount) {
+        LOG(ERROR) << "Invalid trackIndex " << trackIndex << " for trackCount " << mTrackCount;
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    } else if (info == nullptr) {
+        LOG(ERROR) << "MediaSampleInfo pointer is NULL.";
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    }
+
+    media_status_t status = positionExtractorForTrack_l(trackIndex);
+    if (status == AMEDIA_OK) {
+        info->presentationTimeUs = AMediaExtractor_getSampleTime(mExtractor);
+        info->flags = AMediaExtractor_getSampleFlags(mExtractor);
+        info->size = AMediaExtractor_getSampleSize(mExtractor);
+    } else if (status == AMEDIA_ERROR_END_OF_STREAM) {
+        info->presentationTimeUs = 0;
+        info->flags = SAMPLE_FLAG_END_OF_STREAM;
+        info->size = 0;
+    }
+
+    return status;
+}
+
+media_status_t MediaSampleReaderNDK::readSampleDataForTrack(int trackIndex, uint8_t* buffer,
+                                                            size_t bufferSize) {
+    std::scoped_lock lock(mExtractorMutex);
+
+    if (trackIndex < 0 || trackIndex >= mTrackCount) {
+        LOG(ERROR) << "Invalid trackIndex " << trackIndex << " for trackCount " << mTrackCount;
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    } else if (buffer == nullptr) {
+        LOG(ERROR) << "buffer pointer is NULL";
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    }
+
+    media_status_t status = positionExtractorForTrack_l(trackIndex);
+    if (status != AMEDIA_OK) return status;
+
+    ssize_t sampleSize = AMediaExtractor_getSampleSize(mExtractor);
+    if (bufferSize < sampleSize) {
+        LOG(ERROR) << "Buffer is too small for sample, " << bufferSize << " vs " << sampleSize;
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    }
+
+    ssize_t bytesRead = AMediaExtractor_readSampleData(mExtractor, buffer, bufferSize);
+    if (bytesRead < sampleSize) {
+        LOG(ERROR) << "Unable to read full sample, " << bytesRead << " vs " << sampleSize;
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    }
+
+    return AMEDIA_OK;
+}
+
+AMediaFormat* MediaSampleReaderNDK::getFileFormat() {
+    return AMediaExtractor_getFileFormat(mExtractor);
+}
+
+size_t MediaSampleReaderNDK::getTrackCount() const {
+    return mTrackCount;
+}
+
+AMediaFormat* MediaSampleReaderNDK::getTrackFormat(int trackIndex) {
+    if (trackIndex < 0 || trackIndex >= mTrackCount) {
+        LOG(ERROR) << "Invalid trackIndex " << trackIndex << " for trackCount " << mTrackCount;
+        return AMediaFormat_new();
+    }
+
+    return AMediaExtractor_getTrackFormat(mExtractor, trackIndex);
+}
+
+}  // namespace android
diff --git a/media/libmediatranscoding/transcoder/include/media/MediaSample.h b/media/libmediatranscoding/transcoder/include/media/MediaSample.h
new file mode 100644
index 0000000..2b9be9f
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/include/media/MediaSample.h
@@ -0,0 +1,94 @@
+/*
+ * 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.
+ */
+
+#ifndef ANDROID_MEDIA_SAMPLE_H
+#define ANDROID_MEDIA_SAMPLE_H
+
+#include <cstdint>
+
+namespace android {
+
+/**
+ * Media sample flags.
+ * These flags purposely match the media NDK's buffer and extractor flags with one exception. The
+ * NDK extractor's flag for encrypted samples (AMEDIAEXTRACTOR_SAMPLE_FLAG_ENCRYPTED) is equal to 2,
+ * i.e. the same as SAMPLE_FLAG_CODEC_CONFIG below and NDK's AMEDIACODEC_BUFFER_FLAG_CODEC_CONFIG.
+ * Sample producers based on the NDK's extractor is responsible for catching those values.
+ * Note that currently the media transcoder does not support encrypted samples.
+ */
+enum : uint32_t {
+    SAMPLE_FLAG_SYNC_SAMPLE = 1,
+    SAMPLE_FLAG_CODEC_CONFIG = 2,
+    SAMPLE_FLAG_END_OF_STREAM = 4,
+    SAMPLE_FLAG_PARTIAL_FRAME = 8,
+};
+
+// Check that the sample flags have the expected NDK meaning.
+namespace {
+#include <media/NdkMediaCodec.h>
+#include <media/NdkMediaExtractor.h>
+
+static_assert(SAMPLE_FLAG_SYNC_SAMPLE == AMEDIAEXTRACTOR_SAMPLE_FLAG_SYNC,
+              "Sample flag mismatch: SYNC_SAMPLE");
+static_assert(SAMPLE_FLAG_CODEC_CONFIG == AMEDIACODEC_BUFFER_FLAG_CODEC_CONFIG,
+              "Sample flag mismatch: CODEC_CONFIG");
+static_assert(SAMPLE_FLAG_END_OF_STREAM == AMEDIACODEC_BUFFER_FLAG_END_OF_STREAM,
+              "Sample flag mismatch: END_OF_STREAM");
+static_assert(SAMPLE_FLAG_PARTIAL_FRAME == AMEDIACODEC_BUFFER_FLAG_PARTIAL_FRAME,
+              "Sample flag mismatch: PARTIAL_FRAME");
+}  // anonymous namespace
+
+/**
+ * MediaSampleInfo is an object that carries information about a compressed media sample without
+ * holding any sample data.
+ */
+struct MediaSampleInfo {
+    /** The sample's presentation timestamp in microseconds. */
+    int64_t presentationTimeUs = 0;
+
+    /** The size of the compressed sample data in bytes. */
+    size_t size = 0;
+
+    /** Sample flags. */
+    uint32_t flags = 0;
+};
+
+/**
+ * MediaSample holds a compressed media sample in memory.
+ */
+struct MediaSample {
+    /**
+     * Byte buffer containing the sample's compressed data.
+     * The memory backing this buffer is not managed by the MediaSample object so a separate
+     * mechanism to release a buffer is needed between a producer and a consumer.
+     */
+    const uint8_t* buffer = nullptr;
+
+    /** Offset, in bytes, to the sample's compressed data inside the buffer. */
+    size_t dataOffset = 0;
+
+    /**
+     * Buffer identifier. This identifier is likely only meaningful to the sample data producer and
+     * can be used for reclaiming the buffer once a consumer is done processing it.
+     */
+    uint32_t bufferId = 0xBAADF00D;
+
+    /** Media sample information. */
+    MediaSampleInfo info;
+};
+
+}  // namespace android
+#endif  // ANDROID_MEDIA_SAMPLE_H
diff --git a/media/libmediatranscoding/transcoder/include/media/MediaSampleReader.h b/media/libmediatranscoding/transcoder/include/media/MediaSampleReader.h
new file mode 100644
index 0000000..acebac2
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/include/media/MediaSampleReader.h
@@ -0,0 +1,100 @@
+/*
+ * 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.
+ */
+
+#ifndef ANDROID_MEDIA_SAMPLE_READER_H
+#define ANDROID_MEDIA_SAMPLE_READER_H
+
+#include <media/MediaSample.h>
+#include <media/NdkMediaError.h>
+#include <media/NdkMediaFormat.h>
+
+namespace android {
+
+/**
+ * MediaSampleReader is an interface for reading media samples from a container.
+ * MediaSampleReader allows for reading samples from multiple tracks independently of each other
+ * while preserving the order of samples within each individual track.
+ * MediaSampleReader implementations are thread safe and can be used by multiple threads
+ * concurrently. But note that MediaSampleReader only maintains one state per track so concurrent
+ * usage of the same track from multiple threads has no benefit.
+ */
+class MediaSampleReader {
+public:
+    /**
+     * Returns the file format of the media container as a AMediaFormat.
+     * The caller is responsible for releasing the format when finished with it using
+     * AMediaFormat_delete().
+     * @return The file media format.
+     */
+    virtual AMediaFormat* getFileFormat() = 0;
+
+    /**
+     * Returns the number of tracks in the media container.
+     * @return The number of tracks.
+     */
+    virtual size_t getTrackCount() const = 0;
+
+    /**
+     * Returns the media format of a specific track as a AMediaFormat.
+     * The caller is responsible for releasing the format when finished with it using
+     * AMediaFormat_delete().
+     * @param trackIndex The track index (zero-based).
+     * @return The track media format.
+     */
+    virtual AMediaFormat* getTrackFormat(int trackIndex) = 0;
+
+    /**
+     * Returns the sample information for the current sample in the specified track.
+     * @param trackIndex The track index (zero-based).
+     * @param info Pointer to a MediaSampleInfo object where the sample information is written.
+     * @return AMEDIA_OK on success, AMEDIA_ERROR_END_OF_STREAM if there are no more samples to read
+     * from the track and AMEDIA_ERROR_INVALID_PARAMETER if trackIndex is out of bounds or the
+     * info pointer is NULL. Other AMEDIA_ERROR_* return values may not be recoverable.
+     */
+    virtual media_status_t getSampleInfoForTrack(int trackIndex, MediaSampleInfo* info) = 0;
+
+    /**
+     * Reads the current sample's data into the supplied buffer.
+     * @param trackIndex The track index (zero-based).
+     * @param buffer The buffer to write the sample's data to.
+     * @param bufferSize The size of the supplied buffer.
+     * @return AMEDIA_OK on success, AMEDIA_ERROR_END_OF_STREAM if there are no more samples to read
+     * from the track and AMEDIA_ERROR_INVALID_PARAMETER if trackIndex is out of bounds, if the
+     * buffer pointer is NULL or if bufferSize is too small for the sample. Other AMEDIA_ERROR_*
+     * return values may not be recoverable.
+     */
+    virtual media_status_t readSampleDataForTrack(int trackIndex, uint8_t* buffer,
+                                                  size_t bufferSize) = 0;
+
+    /**
+     * Advance the specified track to the next sample.
+     * @param trackIndex The track index (zero-based).
+     */
+    virtual void advanceTrack(int trackIndex) = 0;
+
+    /** Destructor. */
+    virtual ~MediaSampleReader() = default;
+
+    /** Constructor. */
+    MediaSampleReader() = default;
+
+private:
+    MediaSampleReader(const MediaSampleReader&) = delete;
+    MediaSampleReader& operator=(const MediaSampleReader&) = delete;
+};
+
+}  // namespace android
+#endif  // ANDROID_MEDIA_SAMPLE_READER_H
diff --git a/media/libmediatranscoding/transcoder/include/media/MediaSampleReaderNDK.h b/media/libmediatranscoding/transcoder/include/media/MediaSampleReaderNDK.h
new file mode 100644
index 0000000..668be9b
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/include/media/MediaSampleReaderNDK.h
@@ -0,0 +1,111 @@
+/*
+ * 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.
+ */
+
+#ifndef ANDROID_MEDIA_SAMPLE_READER_NDK_H
+#define ANDROID_MEDIA_SAMPLE_READER_NDK_H
+
+#include <media/MediaSampleReader.h>
+#include <media/NdkMediaExtractor.h>
+
+#include <mutex>
+#include <vector>
+
+namespace android {
+
+/**
+ * MediaSampleReaderNDK is a concrete implementation of the MediaSampleReader interface based on the
+ * media NDK extractor.
+ */
+class MediaSampleReaderNDK : public MediaSampleReader {
+public:
+    /**
+     * Creates a new MediaSampleReaderNDK instance wrapped in a shared pointer.
+     * @param fd Source file descriptor. The caller is responsible for closing the fd and it is safe
+     *           to do so when this method returns.
+     * @param offset Source data offset.
+     * @param size Source data size.
+     * @return A shared pointer referencing the new MediaSampleReaderNDK instance on success, or an
+     *         empty shared pointer if an error occurred.
+     */
+    static std::shared_ptr<MediaSampleReader> createFromFd(int fd, size_t offset, size_t size);
+
+    AMediaFormat* getFileFormat() override;
+    size_t getTrackCount() const override;
+    AMediaFormat* getTrackFormat(int trackIndex) override;
+    media_status_t getSampleInfoForTrack(int trackIndex, MediaSampleInfo* info) override;
+    media_status_t readSampleDataForTrack(int trackIndex, uint8_t* buffer,
+                                          size_t bufferSize) override;
+    void advanceTrack(int trackIndex) override;
+
+    virtual ~MediaSampleReaderNDK() override;
+
+private:
+    /**
+     * Creates a new MediaSampleReaderNDK object from an AMediaExtractor. The extractor needs to be
+     * initialized with a valid data source before attempting to create a MediaSampleReaderNDK.
+     * @param extractor The initialized media extractor.
+     */
+    MediaSampleReaderNDK(AMediaExtractor* extractor);
+    media_status_t init();
+
+    AMediaExtractor* mExtractor = nullptr;
+    std::mutex mExtractorMutex;
+    const size_t mTrackCount;
+
+    int mExtractorTrackIndex = -1;
+    uint64_t mExtractorSampleIndex = 0;
+
+    /**
+     * SamplePosition describes the position of a single sample in the media file using its
+     * timestamp and index in the file.
+     */
+    struct SamplePosition {
+        uint64_t index = 0;
+        int64_t timeStampUs = 0;
+        bool isSet = false;
+
+        void set(uint64_t sampleIndex, int64_t sampleTimeUs) {
+            index = sampleIndex;
+            timeStampUs = sampleTimeUs;
+            isSet = true;
+        }
+
+        void reset() { isSet = false; }
+    };
+
+    /**
+     * SampleCursor keeps track of the sample position for a specific track. When the track is
+     * advanced, previous is set to current, current to next and next is reset. As the extractor
+     * advances over the combined timeline of tracks, it updates current and next for the track it
+     * points to if they are not already set.
+     */
+    struct SampleCursor {
+        SamplePosition previous;
+        SamplePosition current;
+        SamplePosition next;
+    };
+
+    /** Samples cursor for each track in the file. */
+    std::vector<SampleCursor> mTrackCursors;
+
+    bool advanceExtractor_l();
+    media_status_t positionExtractorForTrack_l(int trackIndex);
+    media_status_t seekExtractorBackwards_l(int64_t targetTimeUs, int targetTrackIndex,
+                                            uint64_t targetSampleIndex);
+};
+
+}  // namespace android
+#endif  // ANDROID_MEDIA_SAMPLE_READER_NDK_H
diff --git a/media/libmediatranscoding/transcoder/tests/Android.bp b/media/libmediatranscoding/transcoder/tests/Android.bp
new file mode 100644
index 0000000..99b3245
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/tests/Android.bp
@@ -0,0 +1,39 @@
+// Unit tests for libmediatranscoder.
+
+filegroup {
+    name: "test_assets",
+    srcs: ["assets/*"],
+}
+
+cc_defaults {
+    name: "testdefaults",
+
+    header_libs: [
+        "libbase_headers",
+        "libmedia_headers",
+    ],
+
+    shared_libs: [
+        "libbase",
+        "libcutils",
+        "libmediandk",
+        "libmediatranscoder",
+        "libutils",
+    ],
+
+    cflags: [
+        "-Werror",
+        "-Wall",
+    ],
+
+    data: [":test_assets"],
+    test_config_template: "AndroidTestTemplate.xml",
+    test_suites: ["device-tests", "TranscoderTests"],
+}
+
+// MediaSampleReaderNDK unit test
+cc_test {
+    name: "MediaSampleReaderNDKTests",
+    defaults: ["testdefaults"],
+    srcs: ["MediaSampleReaderNDKTests.cpp"],
+}
diff --git a/media/libmediatranscoding/transcoder/tests/AndroidTestTemplate.xml b/media/libmediatranscoding/transcoder/tests/AndroidTestTemplate.xml
new file mode 100644
index 0000000..23d1bab
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/tests/AndroidTestTemplate.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+<configuration description="Unit test configuration for {MODULE}">
+    <option name="test-suite-tag" value="TranscoderTests" />
+    <target_preparer class="com.android.tradefed.targetprep.PushFilePreparer">
+        <option name="cleanup" value="false" />
+        <option name="push-file"
+            key="assets"
+            value="/data/local/tmp/TranscoderTestAssets" />
+    </target_preparer>
+
+    <test class="com.android.tradefed.testtype.GTest" >
+        <option name="module-name" value="{MODULE}" />
+    </test>
+</configuration>
+
diff --git a/media/libmediatranscoding/transcoder/tests/MediaSampleReaderNDKTests.cpp b/media/libmediatranscoding/transcoder/tests/MediaSampleReaderNDKTests.cpp
new file mode 100644
index 0000000..858fcb3
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/tests/MediaSampleReaderNDKTests.cpp
@@ -0,0 +1,170 @@
+/*
+ * 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.
+ */
+
+// Unit Test for MediaSampleReaderNDK
+
+// #define LOG_NDEBUG 0
+#define LOG_TAG "MediaSampleReaderNDKTests"
+
+#include <android-base/logging.h>
+#include <android/binder_manager.h>
+#include <android/binder_process.h>
+#include <fcntl.h>
+#include <gtest/gtest.h>
+#include <media/MediaSampleReaderNDK.h>
+#include <utils/Timers.h>
+
+// TODO(b/153453392): Test more asset types and validate sample data from readSampleDataForTrack.
+
+namespace android {
+
+#define SEC_TO_USEC(s) ((s)*1000 * 1000)
+
+class MediaSampleReaderNDKTests : public ::testing::Test {
+public:
+    MediaSampleReaderNDKTests() { LOG(DEBUG) << "MediaSampleReaderNDKTests created"; }
+
+    void SetUp() override {
+        LOG(DEBUG) << "MediaSampleReaderNDKTests set up";
+        const char* sourcePath =
+                "/data/local/tmp/TranscoderTestAssets/cubicle_avc_480x240_aac_24KHz.mp4";
+
+        mExtractor = AMediaExtractor_new();
+        ASSERT_NE(mExtractor, nullptr);
+
+        mSourceFd = open(sourcePath, O_RDONLY);
+        ASSERT_GT(mSourceFd, 0);
+
+        mFileSize = lseek(mSourceFd, 0, SEEK_END);
+        lseek(mSourceFd, 0, SEEK_SET);
+
+        media_status_t status =
+                AMediaExtractor_setDataSourceFd(mExtractor, mSourceFd, 0, mFileSize);
+        ASSERT_EQ(status, AMEDIA_OK);
+
+        mTrackCount = AMediaExtractor_getTrackCount(mExtractor);
+        for (size_t trackIndex = 0; trackIndex < mTrackCount; trackIndex++) {
+            AMediaExtractor_selectTrack(mExtractor, trackIndex);
+        }
+    }
+
+    void initExtractorTimestamps() {
+        // Save all sample timestamps, per track, as reported by the extractor.
+        mExtractorTimestamps.resize(mTrackCount);
+        do {
+            const int trackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);
+            const int64_t sampleTime = AMediaExtractor_getSampleTime(mExtractor);
+
+            mExtractorTimestamps[trackIndex].push_back(sampleTime);
+        } while (AMediaExtractor_advance(mExtractor));
+    }
+
+    void TearDown() override {
+        LOG(DEBUG) << "MediaSampleReaderNDKTests tear down";
+        AMediaExtractor_delete(mExtractor);
+        close(mSourceFd);
+    }
+
+    ~MediaSampleReaderNDKTests() { LOG(DEBUG) << "MediaSampleReaderNDKTests destroyed"; }
+
+    AMediaExtractor* mExtractor = nullptr;
+    size_t mTrackCount;
+    int mSourceFd;
+    size_t mFileSize;
+    std::vector<std::vector<int64_t>> mExtractorTimestamps;
+};
+
+TEST_F(MediaSampleReaderNDKTests, TestSampleTimes) {
+    LOG(DEBUG) << "TestSampleTimes Starts";
+
+    std::shared_ptr<MediaSampleReader> sampleReader =
+            MediaSampleReaderNDK::createFromFd(mSourceFd, 0, mFileSize);
+    ASSERT_TRUE(sampleReader);
+
+    MediaSampleInfo info;
+    int trackEosCount = 0;
+    std::vector<bool> trackReachedEos(mTrackCount, false);
+    std::vector<std::vector<int64_t>> readerTimestamps(mTrackCount);
+
+    // Initialize the extractor timestamps.
+    initExtractorTimestamps();
+
+    // Read 5s of each track at a time.
+    const int64_t chunkDurationUs = SEC_TO_USEC(5);
+    int64_t chunkEndTimeUs = chunkDurationUs;
+
+    // Loop until all tracks have reached End Of Stream.
+    while (trackEosCount < mTrackCount) {
+        for (int trackIndex = 0; trackIndex < mTrackCount; trackIndex++) {
+            if (trackReachedEos[trackIndex]) continue;
+
+            // Advance current track to next chunk end time.
+            do {
+                media_status_t status = sampleReader->getSampleInfoForTrack(trackIndex, &info);
+                if (status != AMEDIA_OK) {
+                    ASSERT_EQ(status, AMEDIA_ERROR_END_OF_STREAM);
+                    ASSERT_TRUE((info.flags & SAMPLE_FLAG_END_OF_STREAM) != 0);
+                    trackReachedEos[trackIndex] = true;
+                    trackEosCount++;
+                    break;
+                }
+                ASSERT_TRUE((info.flags & SAMPLE_FLAG_END_OF_STREAM) == 0);
+                readerTimestamps[trackIndex].push_back(info.presentationTimeUs);
+                sampleReader->advanceTrack(trackIndex);
+            } while (info.presentationTimeUs < chunkEndTimeUs);
+        }
+        chunkEndTimeUs += chunkDurationUs;
+    }
+
+    for (int trackIndex = 0; trackIndex < mTrackCount; trackIndex++) {
+        LOG(DEBUG) << "Track " << trackIndex << ", comparing "
+                   << readerTimestamps[trackIndex].size() << " samples.";
+        ASSERT_EQ(readerTimestamps[trackIndex].size(), mExtractorTimestamps[trackIndex].size());
+        for (size_t sampleIndex = 0; sampleIndex < readerTimestamps[trackIndex].size();
+             sampleIndex++) {
+            ASSERT_EQ(readerTimestamps[trackIndex][sampleIndex],
+                      mExtractorTimestamps[trackIndex][sampleIndex]);
+        }
+    }
+}
+
+TEST_F(MediaSampleReaderNDKTests, TestInvalidFd) {
+    std::shared_ptr<MediaSampleReader> sampleReader =
+            MediaSampleReaderNDK::createFromFd(0, 0, mFileSize);
+    ASSERT_TRUE(sampleReader == nullptr);
+
+    sampleReader = MediaSampleReaderNDK::createFromFd(-1, 0, mFileSize);
+    ASSERT_TRUE(sampleReader == nullptr);
+}
+
+TEST_F(MediaSampleReaderNDKTests, TestZeroSize) {
+    std::shared_ptr<MediaSampleReader> sampleReader =
+            MediaSampleReaderNDK::createFromFd(mSourceFd, 0, 0);
+    ASSERT_TRUE(sampleReader == nullptr);
+}
+
+TEST_F(MediaSampleReaderNDKTests, TestInvalidOffset) {
+    std::shared_ptr<MediaSampleReader> sampleReader =
+            MediaSampleReaderNDK::createFromFd(mSourceFd, mFileSize, mFileSize);
+    ASSERT_TRUE(sampleReader == nullptr);
+}
+
+}  // namespace android
+
+int main(int argc, char** argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
diff --git a/media/libmediatranscoding/transcoder/tests/README.md b/media/libmediatranscoding/transcoder/tests/README.md
new file mode 100644
index 0000000..59417b0
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/tests/README.md
@@ -0,0 +1,14 @@
+## Transcoder Testing ##
+---
+#### Transcoder unit tests :
+To run all transcoder unit tests, run the supplied script from this folder:
+
+```
+./build_and_run_all_unit_tests.sh
+```
+
+To run individual unit test modules, use atest:
+
+```
+atest MediaSampleReaderNDK
+```
diff --git a/media/libmediatranscoding/transcoder/tests/assets/cubicle_avc_480x240_aac_24KHz.mp4 b/media/libmediatranscoding/transcoder/tests/assets/cubicle_avc_480x240_aac_24KHz.mp4
new file mode 100644
index 0000000..ef7e1b7
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/tests/assets/cubicle_avc_480x240_aac_24KHz.mp4
Binary files differ
diff --git a/media/libmediatranscoding/transcoder/tests/build_and_run_all_unit_tests.sh b/media/libmediatranscoding/transcoder/tests/build_and_run_all_unit_tests.sh
new file mode 100755
index 0000000..2d9dccf
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/tests/build_and_run_all_unit_tests.sh
@@ -0,0 +1,26 @@
+#!/bin/bash
+#
+# Run tests in this directory.
+#
+
+if [ "$SYNC_FINISHED" != true ]; then
+  if [ -z "$ANDROID_BUILD_TOP" ]; then
+      echo "Android build environment not set"
+      exit -1
+  fi
+
+  # ensure we have mm
+  . $ANDROID_BUILD_TOP/build/envsetup.sh
+
+  mm
+
+  echo "waiting for device"
+
+  adb root && adb wait-for-device remount && adb sync
+fi
+adb push assets /data/local/tmp/TranscoderTestAssets
+
+echo "========================================"
+
+echo "testing MediaSampleReaderNDK"
+adb shell /data/nativetest64/MediaSampleReaderNDKTests/MediaSampleReaderNDKTests