Transcoder: Added MediaTrackTranscoder and VideoTrackTranscoder

A track transcoder transcodes samples from a single track of a media file.
MediaTrackTranscoder is the base class for all track transcoder, and
VideoTrackTranscoder is a concrete implementation for video tracks.

Test: Unit test.
Bug: 152091443
Change-Id: I7980a3cda40229004b6bca5212d3e903f19a3017
diff --git a/media/libmediatranscoding/transcoder/MediaTrackTranscoder.cpp b/media/libmediatranscoding/transcoder/MediaTrackTranscoder.cpp
new file mode 100644
index 0000000..1673b5b
--- /dev/null
+++ b/media/libmediatranscoding/transcoder/MediaTrackTranscoder.cpp
@@ -0,0 +1,104 @@
+/*
+ * 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 "MediaTrackTranscoder"
+
+#include <android-base/logging.h>
+#include <media/MediaTrackTranscoder.h>
+
+namespace android {
+
+media_status_t MediaTrackTranscoder::configure(
+        const std::shared_ptr<MediaSampleReader>& mediaSampleReader, int trackIndex,
+        const std::shared_ptr<AMediaFormat>& destinationFormat) {
+    std::scoped_lock lock{mStateMutex};
+
+    if (mState != UNINITIALIZED) {
+        LOG(ERROR) << "Configure can only be called once";
+        return AMEDIA_ERROR_UNSUPPORTED;
+    }
+
+    if (mediaSampleReader == nullptr) {
+        LOG(ERROR) << "MediaSampleReader is null";
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    }
+    if (trackIndex < 0 || trackIndex >= mediaSampleReader->getTrackCount()) {
+        LOG(ERROR) << "TrackIndex is invalid " << trackIndex;
+        return AMEDIA_ERROR_INVALID_PARAMETER;
+    }
+
+    mMediaSampleReader = mediaSampleReader;
+    mTrackIndex = trackIndex;
+
+    mSourceFormat =
+            std::shared_ptr<AMediaFormat>(mMediaSampleReader->getTrackFormat(mTrackIndex),
+                                          std::bind(AMediaFormat_delete, std::placeholders::_1));
+    if (mSourceFormat == nullptr) {
+        LOG(ERROR) << "Unable to get format for track #" << mTrackIndex;
+        return AMEDIA_ERROR_MALFORMED;
+    }
+
+    media_status_t status = configureDestinationFormat(destinationFormat);
+    if (status != AMEDIA_OK) {
+        LOG(ERROR) << "configure failed with error " << status;
+        return status;
+    }
+
+    mState = CONFIGURED;
+    return AMEDIA_OK;
+}
+
+bool MediaTrackTranscoder::start() {
+    std::scoped_lock lock{mStateMutex};
+
+    if (mState != CONFIGURED) {
+        LOG(ERROR) << "TrackTranscoder must be configured before started";
+        return false;
+    }
+
+    mTranscodingThread = std::thread([this] {
+        media_status_t status = runTranscodeLoop();
+
+        // Notify the client.
+        if (auto callbacks = mTranscoderCallback.lock()) {
+            if (status != AMEDIA_OK) {
+                callbacks->onTrackError(this, status);
+            } else {
+                callbacks->onTrackFinished(this);
+            }
+        }
+    });
+
+    mState = STARTED;
+    return true;
+}
+
+bool MediaTrackTranscoder::stop() {
+    std::scoped_lock lock{mStateMutex};
+
+    if (mState == STARTED) {
+        abortTranscodeLoop();
+        mTranscodingThread.join();
+        mState = STOPPED;
+        return true;
+    }
+
+    LOG(ERROR) << "TrackTranscoder must be started before stopped";
+    return false;
+}
+
+}  // namespace android
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