Added MediaSampleReader interface and an NDK based implementation.
MediaSampleReader is an interface for reading media samples from
multiple tracks independently from each other. Each track maintains
its own time state and reading from other tracks does not effect that.
Test: Unit test.
Bug: 152091443
Change-Id: Ib8c965df5d2a47fc6218ceb80b40d0687fb3b531
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