media/module/libmediatranscoding/transcoder/MediaSampleReaderNDK.cpp - third_party/android/platform/frameworks/av - Git at Google

 /*
  * 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 <cmath>

 namespace android {

 // Check that the extractor sample flags have the expected NDK meaning.
 static_assert(SAMPLE_FLAG_SYNC_SAMPLE == AMEDIAEXTRACTOR_SAMPLE_FLAG_SYNC,
               "Sample flag mismatch: SYNC_SAMPLE");

 // 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));
     return sampleReader;
 }

 MediaSampleReaderNDK::MediaSampleReaderNDK(AMediaExtractor* extractor)
       : mExtractor(extractor), mTrackCount(AMediaExtractor_getTrackCount(mExtractor)) {
     if (mTrackCount > 0) {
         mTrackCursors.resize(mTrackCount);
     }
 }

 MediaSampleReaderNDK::~MediaSampleReaderNDK() {
     if (mExtractor != nullptr) {
         AMediaExtractor_delete(mExtractor);
     }
 }

 void MediaSampleReaderNDK::advanceTrack_l(int trackIndex) {
     if (!mEnforceSequentialAccess) {
         // 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)moveToTrack_l(trackIndex);
     }

     SampleCursor& cursor = mTrackCursors[trackIndex];
     cursor.previous = cursor.current;
     cursor.current = cursor.next;
     cursor.next.reset();

     if (mEnforceSequentialAccess && trackIndex == mExtractorTrackIndex) {
         while (advanceExtractor_l()) {
             SampleCursor& cursor = mTrackCursors[mExtractorTrackIndex];
             if (cursor.current.isSet && cursor.current.index == mExtractorSampleIndex) {
                 if (mExtractorTrackIndex != trackIndex) {
                     mTrackSignals[mExtractorTrackIndex].notify_all();
                 }
                 break;
             }
         }
     }
     return;
 }

 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();
     }

     // Update the extractor's sample index even if this track reaches EOS, so that the other tracks
     // are not given an incorrect extractor position.
     mExtractorSampleIndex++;
     if (!AMediaExtractor_advance(mExtractor)) {
         LOG(DEBUG) << "  EOS in advanceExtractor_l";
         mEosReached = true;
         for (auto it = mTrackSignals.begin(); it != mTrackSignals.end(); ++it) {
             it->second.notify_all();
         }
         return false;
     }

     mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);

     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;
     }

     mEosReached = false;
     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;
 }

 media_status_t MediaSampleReaderNDK::moveToSample_l(SamplePosition& pos, int trackIndex) {
     // Seek backwards if the extractor is ahead of the sample.
     if (pos.isSet && mExtractorSampleIndex > pos.index) {
         media_status_t status = seekExtractorBackwards_l(pos.timeStampUs, trackIndex, pos.index);
         if (status != AMEDIA_OK) return status;
     }

     // Advance until extractor points to the sample.
     while (!(pos.isSet && pos.index == mExtractorSampleIndex)) {
         if (!advanceExtractor_l()) {
             return AMEDIA_ERROR_END_OF_STREAM;
         }
     }

     return AMEDIA_OK;
 }

 media_status_t MediaSampleReaderNDK::moveToTrack_l(int trackIndex) {
     return moveToSample_l(mTrackCursors[trackIndex].current, trackIndex);
 }

 media_status_t MediaSampleReaderNDK::waitForTrack_l(int trackIndex,
                                                     std::unique_lock<std::mutex>& lockHeld) {
     while (trackIndex != mExtractorTrackIndex && !mEosReached && mEnforceSequentialAccess) {
         mTrackSignals[trackIndex].wait(lockHeld);
     }

     if (mEosReached) {
         return AMEDIA_ERROR_END_OF_STREAM;
     }

     if (!mEnforceSequentialAccess) {
         return moveToTrack_l(trackIndex);
     }

     return AMEDIA_OK;
 }

 media_status_t MediaSampleReaderNDK::primeExtractorForTrack_l(
         int trackIndex, std::unique_lock<std::mutex>& lockHeld) {
     if (mExtractorTrackIndex < 0) {
         mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);
         if (mExtractorTrackIndex < 0) {
             return AMEDIA_ERROR_END_OF_STREAM;
         }
         mTrackCursors[mExtractorTrackIndex].current.set(mExtractorSampleIndex,
                                                         AMediaExtractor_getSampleTime(mExtractor));
     }

     if (mEnforceSequentialAccess) {
         return waitForTrack_l(trackIndex, lockHeld);
     } else {
         return moveToTrack_l(trackIndex);
     }
 }

 media_status_t MediaSampleReaderNDK::selectTrack(int trackIndex) {
     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 (mTrackSignals.find(trackIndex) != mTrackSignals.end()) {
         LOG(ERROR) << "TrackIndex " << trackIndex << " already selected";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     } else if (mExtractorTrackIndex >= 0) {
         LOG(ERROR) << "Tracks must be selected before sample reading begins.";
         return AMEDIA_ERROR_UNSUPPORTED;
     }

     media_status_t status = AMediaExtractor_selectTrack(mExtractor, trackIndex);
     if (status != AMEDIA_OK) {
         LOG(ERROR) << "AMediaExtractor_selectTrack returned error: " << status;
         return status;
     }

     mTrackSignals.emplace(std::piecewise_construct, std::forward_as_tuple(trackIndex),
                           std::forward_as_tuple());
     return AMEDIA_OK;
 }

 media_status_t MediaSampleReaderNDK::unselectTrack(int trackIndex) {
     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 (mExtractorTrackIndex >= 0) {
         LOG(ERROR) << "unselectTrack must be called before sample reading begins.";
         return AMEDIA_ERROR_UNSUPPORTED;
     }

     auto it = mTrackSignals.find(trackIndex);
     if (it == mTrackSignals.end()) {
         LOG(ERROR) << "TrackIndex " << trackIndex << " is not selected";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     }
     mTrackSignals.erase(it);

     media_status_t status = AMediaExtractor_unselectTrack(mExtractor, trackIndex);
     if (status != AMEDIA_OK) {
         LOG(ERROR) << "AMediaExtractor_selectTrack returned error: " << status;
         return status;
     }

     return AMEDIA_OK;
 }

 media_status_t MediaSampleReaderNDK::setEnforceSequentialAccess(bool enforce) {
     LOG(DEBUG) << "setEnforceSequentialAccess( " << enforce << " )";

     std::scoped_lock lock(mExtractorMutex);

     if (mEnforceSequentialAccess && !enforce) {
         // If switching from enforcing to not enforcing sequential access there may be threads
         // waiting that needs to be woken up.
         for (auto it = mTrackSignals.begin(); it != mTrackSignals.end(); ++it) {
             it->second.notify_all();
         }
     } else if (!mEnforceSequentialAccess && enforce && mExtractorTrackIndex >= 0) {
         // If switching from not enforcing to enforcing sequential access the extractor needs to be
         // positioned for the track farthest behind so that it won't get stuck waiting.
         struct {
             SamplePosition* pos = nullptr;
             int trackIndex = -1;
         } earliestSample;

         for (int trackIndex = 0; trackIndex < mTrackCount; ++trackIndex) {
             SamplePosition& lastKnownTrackPosition = mTrackCursors[trackIndex].current.isSet
                                                              ? mTrackCursors[trackIndex].current
                                                              : mTrackCursors[trackIndex].previous;

             if (lastKnownTrackPosition.isSet) {
                 if (earliestSample.pos == nullptr ||
                     earliestSample.pos->index > lastKnownTrackPosition.index) {
                     earliestSample.pos = &lastKnownTrackPosition;
                     earliestSample.trackIndex = trackIndex;
                 }
             }
         }

         if (earliestSample.pos == nullptr) {
             LOG(ERROR) << "No known sample position found";
             return AMEDIA_ERROR_UNKNOWN;
         }

         media_status_t status = moveToSample_l(*earliestSample.pos, earliestSample.trackIndex);
         if (status != AMEDIA_OK) return status;

         while (!(mTrackCursors[mExtractorTrackIndex].current.isSet &&
                  mTrackCursors[mExtractorTrackIndex].current.index == mExtractorSampleIndex)) {
             if (!advanceExtractor_l()) {
                 return AMEDIA_ERROR_END_OF_STREAM;
             }
         }
     }

     mEnforceSequentialAccess = enforce;
     return AMEDIA_OK;
 }

 media_status_t MediaSampleReaderNDK::getEstimatedBitrateForTrack(int trackIndex, int32_t* bitrate) {
     std::scoped_lock lock(mExtractorMutex);
     media_status_t status = AMEDIA_OK;

     if (mTrackSignals.find(trackIndex) == mTrackSignals.end()) {
         LOG(ERROR) << "Track is not selected.";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     } else if (bitrate == nullptr) {
         LOG(ERROR) << "bitrate pointer is NULL.";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     } else if (mExtractorTrackIndex >= 0) {
         LOG(ERROR) << "getEstimatedBitrateForTrack must be called before sample reading begins.";
         return AMEDIA_ERROR_UNSUPPORTED;
     }

     // Sample the track.
     static constexpr int64_t kSamplingDurationUs = 10 * 1000 * 1000;  // 10 seconds
     size_t lastSampleSize = 0;
     size_t totalSampleSize = 0;
     int64_t firstSampleTimeUs = 0;
     int64_t lastSampleTimeUs = 0;

     do {
         if (AMediaExtractor_getSampleTrackIndex(mExtractor) == trackIndex) {
             lastSampleTimeUs = AMediaExtractor_getSampleTime(mExtractor);
             if (totalSampleSize == 0) {
                 firstSampleTimeUs = lastSampleTimeUs;
             }

             lastSampleSize = AMediaExtractor_getSampleSize(mExtractor);
             totalSampleSize += lastSampleSize;
         }
     } while ((lastSampleTimeUs - firstSampleTimeUs) < kSamplingDurationUs &&
              AMediaExtractor_advance(mExtractor));

     // Reset the extractor to the beginning.
     status = AMediaExtractor_seekTo(mExtractor, 0, AMEDIAEXTRACTOR_SEEK_PREVIOUS_SYNC);
     if (status != AMEDIA_OK) {
         LOG(ERROR) << "Unable to reset extractor: " << status;
         return status;
     }

     int64_t durationUs = 0;
     const int64_t sampledDurationUs = lastSampleTimeUs - firstSampleTimeUs;

     if (sampledDurationUs < kSamplingDurationUs) {
         // Track is shorter than the sampling duration so use the full track duration to get better
         // accuracy (i.e. don't skip the last sample).
         AMediaFormat* trackFormat = getTrackFormat(trackIndex);
         if (!AMediaFormat_getInt64(trackFormat, AMEDIAFORMAT_KEY_DURATION, &durationUs)) {
             durationUs = 0;
         }
         AMediaFormat_delete(trackFormat);
     }

     if (durationUs == 0) {
         // The sampled duration does not account for the last sample's duration so its size should
         // not be included either.
         totalSampleSize -= lastSampleSize;
         durationUs = sampledDurationUs;
     }

     if (totalSampleSize == 0 || durationUs <= 0) {
         LOG(ERROR) << "Unable to estimate track bitrate";
         return AMEDIA_ERROR_MALFORMED;
     }

     *bitrate = roundf((float)totalSampleSize * 8 * 1000000 / durationUs);
     return AMEDIA_OK;
 }

 media_status_t MediaSampleReaderNDK::getSampleInfoForTrack(int trackIndex, MediaSampleInfo* info) {
     std::unique_lock<std::mutex> lock(mExtractorMutex);

     if (mTrackSignals.find(trackIndex) == mTrackSignals.end()) {
         LOG(ERROR) << "Track not selected.";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     } else if (info == nullptr) {
         LOG(ERROR) << "MediaSampleInfo pointer is NULL.";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     }

     media_status_t status = primeExtractorForTrack_l(trackIndex, lock);
     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;
         LOG(DEBUG) << "  getSampleInfoForTrack #" << trackIndex << ": End Of Stream";
     } else {
         LOG(ERROR) << "  getSampleInfoForTrack #" << trackIndex << ": Error " << status;
     }

     return status;
 }

 media_status_t MediaSampleReaderNDK::readSampleDataForTrack(int trackIndex, uint8_t* buffer,
                                                             size_t bufferSize) {
     std::unique_lock<std::mutex> lock(mExtractorMutex);

     if (mTrackSignals.find(trackIndex) == mTrackSignals.end()) {
         LOG(ERROR) << "Track not selected.";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     } else if (buffer == nullptr) {
         LOG(ERROR) << "buffer pointer is NULL";
         return AMEDIA_ERROR_INVALID_PARAMETER;
     }

     media_status_t status = primeExtractorForTrack_l(trackIndex, lock);
     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;
     }

     advanceTrack_l(trackIndex);

     return AMEDIA_OK;
 }

 void MediaSampleReaderNDK::advanceTrack(int trackIndex) {
     std::scoped_lock lock(mExtractorMutex);

     if (mTrackSignals.find(trackIndex) != mTrackSignals.end()) {
         advanceTrack_l(trackIndex);
     } else {
         LOG(ERROR) << "Trying to advance a track that is not selected (#" << trackIndex << ")";
     }
 }

 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
	/*
	* 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 <cmath>

	namespace android {

	// Check that the extractor sample flags have the expected NDK meaning.
	static_assert(SAMPLE_FLAG_SYNC_SAMPLE == AMEDIAEXTRACTOR_SAMPLE_FLAG_SYNC,
	"Sample flag mismatch: SYNC_SAMPLE");

	// 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));
	return sampleReader;
	}

	MediaSampleReaderNDK::MediaSampleReaderNDK(AMediaExtractor* extractor)
	: mExtractor(extractor), mTrackCount(AMediaExtractor_getTrackCount(mExtractor)) {
	if (mTrackCount > 0) {
	mTrackCursors.resize(mTrackCount);
	}
	}

	MediaSampleReaderNDK::~MediaSampleReaderNDK() {
	if (mExtractor != nullptr) {
	AMediaExtractor_delete(mExtractor);
	}
	}

	void MediaSampleReaderNDK::advanceTrack_l(int trackIndex) {
	if (!mEnforceSequentialAccess) {
	// 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)moveToTrack_l(trackIndex);
	}

	SampleCursor& cursor = mTrackCursors[trackIndex];
	cursor.previous = cursor.current;
	cursor.current = cursor.next;
	cursor.next.reset();

	if (mEnforceSequentialAccess && trackIndex == mExtractorTrackIndex) {
	while (advanceExtractor_l()) {
	SampleCursor& cursor = mTrackCursors[mExtractorTrackIndex];
	if (cursor.current.isSet && cursor.current.index == mExtractorSampleIndex) {
	if (mExtractorTrackIndex != trackIndex) {
	mTrackSignals[mExtractorTrackIndex].notify_all();
	}
	break;
	}
	}
	}
	return;
	}

	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();
	}

	// Update the extractor's sample index even if this track reaches EOS, so that the other tracks
	// are not given an incorrect extractor position.
	mExtractorSampleIndex++;
	if (!AMediaExtractor_advance(mExtractor)) {
	LOG(DEBUG) << " EOS in advanceExtractor_l";
	mEosReached = true;
	for (auto it = mTrackSignals.begin(); it != mTrackSignals.end(); ++it) {
	it->second.notify_all();
	}
	return false;
	}

	mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);

	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;
	}

	mEosReached = false;
	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;
	}

	media_status_t MediaSampleReaderNDK::moveToSample_l(SamplePosition& pos, int trackIndex) {
	// Seek backwards if the extractor is ahead of the sample.
	if (pos.isSet && mExtractorSampleIndex > pos.index) {
	media_status_t status = seekExtractorBackwards_l(pos.timeStampUs, trackIndex, pos.index);
	if (status != AMEDIA_OK) return status;
	}

	// Advance until extractor points to the sample.
	while (!(pos.isSet && pos.index == mExtractorSampleIndex)) {
	if (!advanceExtractor_l()) {
	return AMEDIA_ERROR_END_OF_STREAM;
	}
	}

	return AMEDIA_OK;
	}

	media_status_t MediaSampleReaderNDK::moveToTrack_l(int trackIndex) {
	return moveToSample_l(mTrackCursors[trackIndex].current, trackIndex);
	}

	media_status_t MediaSampleReaderNDK::waitForTrack_l(int trackIndex,
	std::unique_lock<std::mutex>& lockHeld) {
	while (trackIndex != mExtractorTrackIndex && !mEosReached && mEnforceSequentialAccess) {
	mTrackSignals[trackIndex].wait(lockHeld);
	}

	if (mEosReached) {
	return AMEDIA_ERROR_END_OF_STREAM;
	}

	if (!mEnforceSequentialAccess) {
	return moveToTrack_l(trackIndex);
	}

	return AMEDIA_OK;
	}

	media_status_t MediaSampleReaderNDK::primeExtractorForTrack_l(
	int trackIndex, std::unique_lock<std::mutex>& lockHeld) {
	if (mExtractorTrackIndex < 0) {
	mExtractorTrackIndex = AMediaExtractor_getSampleTrackIndex(mExtractor);
	if (mExtractorTrackIndex < 0) {
	return AMEDIA_ERROR_END_OF_STREAM;
	}
	mTrackCursors[mExtractorTrackIndex].current.set(mExtractorSampleIndex,
	AMediaExtractor_getSampleTime(mExtractor));
	}

	if (mEnforceSequentialAccess) {
	return waitForTrack_l(trackIndex, lockHeld);
	} else {
	return moveToTrack_l(trackIndex);
	}
	}

	media_status_t MediaSampleReaderNDK::selectTrack(int trackIndex) {
	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 (mTrackSignals.find(trackIndex) != mTrackSignals.end()) {
	LOG(ERROR) << "TrackIndex " << trackIndex << " already selected";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	} else if (mExtractorTrackIndex >= 0) {
	LOG(ERROR) << "Tracks must be selected before sample reading begins.";
	return AMEDIA_ERROR_UNSUPPORTED;
	}

	media_status_t status = AMediaExtractor_selectTrack(mExtractor, trackIndex);
	if (status != AMEDIA_OK) {
	LOG(ERROR) << "AMediaExtractor_selectTrack returned error: " << status;
	return status;
	}

	mTrackSignals.emplace(std::piecewise_construct, std::forward_as_tuple(trackIndex),
	std::forward_as_tuple());
	return AMEDIA_OK;
	}

	media_status_t MediaSampleReaderNDK::unselectTrack(int trackIndex) {
	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 (mExtractorTrackIndex >= 0) {
	LOG(ERROR) << "unselectTrack must be called before sample reading begins.";
	return AMEDIA_ERROR_UNSUPPORTED;
	}

	auto it = mTrackSignals.find(trackIndex);
	if (it == mTrackSignals.end()) {
	LOG(ERROR) << "TrackIndex " << trackIndex << " is not selected";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	}
	mTrackSignals.erase(it);

	media_status_t status = AMediaExtractor_unselectTrack(mExtractor, trackIndex);
	if (status != AMEDIA_OK) {
	LOG(ERROR) << "AMediaExtractor_selectTrack returned error: " << status;
	return status;
	}

	return AMEDIA_OK;
	}

	media_status_t MediaSampleReaderNDK::setEnforceSequentialAccess(bool enforce) {
	LOG(DEBUG) << "setEnforceSequentialAccess( " << enforce << " )";

	std::scoped_lock lock(mExtractorMutex);

	if (mEnforceSequentialAccess && !enforce) {
	// If switching from enforcing to not enforcing sequential access there may be threads
	// waiting that needs to be woken up.
	for (auto it = mTrackSignals.begin(); it != mTrackSignals.end(); ++it) {
	it->second.notify_all();
	}
	} else if (!mEnforceSequentialAccess && enforce && mExtractorTrackIndex >= 0) {
	// If switching from not enforcing to enforcing sequential access the extractor needs to be
	// positioned for the track farthest behind so that it won't get stuck waiting.
	struct {
	SamplePosition* pos = nullptr;
	int trackIndex = -1;
	} earliestSample;

	for (int trackIndex = 0; trackIndex < mTrackCount; ++trackIndex) {
	SamplePosition& lastKnownTrackPosition = mTrackCursors[trackIndex].current.isSet
	? mTrackCursors[trackIndex].current
	: mTrackCursors[trackIndex].previous;

	if (lastKnownTrackPosition.isSet) {
	if (earliestSample.pos == nullptr \|\|
	earliestSample.pos->index > lastKnownTrackPosition.index) {
	earliestSample.pos = &lastKnownTrackPosition;
	earliestSample.trackIndex = trackIndex;
	}
	}
	}

	if (earliestSample.pos == nullptr) {
	LOG(ERROR) << "No known sample position found";
	return AMEDIA_ERROR_UNKNOWN;
	}

	media_status_t status = moveToSample_l(*earliestSample.pos, earliestSample.trackIndex);
	if (status != AMEDIA_OK) return status;

	while (!(mTrackCursors[mExtractorTrackIndex].current.isSet &&
	mTrackCursors[mExtractorTrackIndex].current.index == mExtractorSampleIndex)) {
	if (!advanceExtractor_l()) {
	return AMEDIA_ERROR_END_OF_STREAM;
	}
	}
	}

	mEnforceSequentialAccess = enforce;
	return AMEDIA_OK;
	}

	media_status_t MediaSampleReaderNDK::getEstimatedBitrateForTrack(int trackIndex, int32_t* bitrate) {
	std::scoped_lock lock(mExtractorMutex);
	media_status_t status = AMEDIA_OK;

	if (mTrackSignals.find(trackIndex) == mTrackSignals.end()) {
	LOG(ERROR) << "Track is not selected.";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	} else if (bitrate == nullptr) {
	LOG(ERROR) << "bitrate pointer is NULL.";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	} else if (mExtractorTrackIndex >= 0) {
	LOG(ERROR) << "getEstimatedBitrateForTrack must be called before sample reading begins.";
	return AMEDIA_ERROR_UNSUPPORTED;
	}

	// Sample the track.
	static constexpr int64_t kSamplingDurationUs = 10 * 1000 * 1000; // 10 seconds
	size_t lastSampleSize = 0;
	size_t totalSampleSize = 0;
	int64_t firstSampleTimeUs = 0;
	int64_t lastSampleTimeUs = 0;

	do {
	if (AMediaExtractor_getSampleTrackIndex(mExtractor) == trackIndex) {
	lastSampleTimeUs = AMediaExtractor_getSampleTime(mExtractor);
	if (totalSampleSize == 0) {
	firstSampleTimeUs = lastSampleTimeUs;
	}

	lastSampleSize = AMediaExtractor_getSampleSize(mExtractor);
	totalSampleSize += lastSampleSize;
	}
	} while ((lastSampleTimeUs - firstSampleTimeUs) < kSamplingDurationUs &&
	AMediaExtractor_advance(mExtractor));

	// Reset the extractor to the beginning.
	status = AMediaExtractor_seekTo(mExtractor, 0, AMEDIAEXTRACTOR_SEEK_PREVIOUS_SYNC);
	if (status != AMEDIA_OK) {
	LOG(ERROR) << "Unable to reset extractor: " << status;
	return status;
	}

	int64_t durationUs = 0;
	const int64_t sampledDurationUs = lastSampleTimeUs - firstSampleTimeUs;

	if (sampledDurationUs < kSamplingDurationUs) {
	// Track is shorter than the sampling duration so use the full track duration to get better
	// accuracy (i.e. don't skip the last sample).
	AMediaFormat* trackFormat = getTrackFormat(trackIndex);
	if (!AMediaFormat_getInt64(trackFormat, AMEDIAFORMAT_KEY_DURATION, &durationUs)) {
	durationUs = 0;
	}
	AMediaFormat_delete(trackFormat);
	}

	if (durationUs == 0) {
	// The sampled duration does not account for the last sample's duration so its size should
	// not be included either.
	totalSampleSize -= lastSampleSize;
	durationUs = sampledDurationUs;
	}

	if (totalSampleSize == 0 \|\| durationUs <= 0) {
	LOG(ERROR) << "Unable to estimate track bitrate";
	return AMEDIA_ERROR_MALFORMED;
	}

	bitrate = roundf((float)totalSampleSize 8 * 1000000 / durationUs);
	return AMEDIA_OK;
	}

	media_status_t MediaSampleReaderNDK::getSampleInfoForTrack(int trackIndex, MediaSampleInfo* info) {
	std::unique_lock<std::mutex> lock(mExtractorMutex);

	if (mTrackSignals.find(trackIndex) == mTrackSignals.end()) {
	LOG(ERROR) << "Track not selected.";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	} else if (info == nullptr) {
	LOG(ERROR) << "MediaSampleInfo pointer is NULL.";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	}

	media_status_t status = primeExtractorForTrack_l(trackIndex, lock);
	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;
	LOG(DEBUG) << " getSampleInfoForTrack #" << trackIndex << ": End Of Stream";
	} else {
	LOG(ERROR) << " getSampleInfoForTrack #" << trackIndex << ": Error " << status;
	}

	return status;
	}

	media_status_t MediaSampleReaderNDK::readSampleDataForTrack(int trackIndex, uint8_t* buffer,
	size_t bufferSize) {
	std::unique_lock<std::mutex> lock(mExtractorMutex);

	if (mTrackSignals.find(trackIndex) == mTrackSignals.end()) {
	LOG(ERROR) << "Track not selected.";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	} else if (buffer == nullptr) {
	LOG(ERROR) << "buffer pointer is NULL";
	return AMEDIA_ERROR_INVALID_PARAMETER;
	}

	media_status_t status = primeExtractorForTrack_l(trackIndex, lock);
	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;
	}

	advanceTrack_l(trackIndex);

	return AMEDIA_OK;
	}

	void MediaSampleReaderNDK::advanceTrack(int trackIndex) {
	std::scoped_lock lock(mExtractorMutex);

	if (mTrackSignals.find(trackIndex) != mTrackSignals.end()) {
	advanceTrack_l(trackIndex);
	} else {
	LOG(ERROR) << "Trying to advance a track that is not selected (#" << trackIndex << ")";
	}
	}

	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