android-34/com/google/android/exoplayer2/extractor/jpeg/JpegExtractor.java - platform/prebuilts/fullsdk/sources - Git at Google

 /*
  * Copyright 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.
  */
 package com.google.android.exoplayer2.extractor.jpeg;

 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;

 import androidx.annotation.IntDef;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.extractor.Extractor;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.extractor.ExtractorOutput;
 import com.google.android.exoplayer2.extractor.PositionHolder;
 import com.google.android.exoplayer2.extractor.SeekMap;
 import com.google.android.exoplayer2.extractor.TrackOutput;
 import com.google.android.exoplayer2.extractor.mp4.Mp4Extractor;
 import com.google.android.exoplayer2.metadata.Metadata;
 import com.google.android.exoplayer2.metadata.mp4.MotionPhotoMetadata;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import java.io.IOException;
 import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;

 /** Extracts JPEG image using the Exif format. */
 public final class JpegExtractor implements Extractor {

   /** Parser states. */
   @Documented
   @Retention(RetentionPolicy.SOURCE)
   @IntDef({
     STATE_READING_MARKER,
     STATE_READING_SEGMENT_LENGTH,
     STATE_READING_SEGMENT,
     STATE_SNIFFING_MOTION_PHOTO_VIDEO,
     STATE_READING_MOTION_PHOTO_VIDEO,
     STATE_ENDED,
   })
   private @interface State {}

   private static final int STATE_READING_MARKER = 0;
   private static final int STATE_READING_SEGMENT_LENGTH = 1;
   private static final int STATE_READING_SEGMENT = 2;
   private static final int STATE_SNIFFING_MOTION_PHOTO_VIDEO = 4;
   private static final int STATE_READING_MOTION_PHOTO_VIDEO = 5;
   private static final int STATE_ENDED = 6;

   private static final int EXIF_ID_CODE_LENGTH = 6;
   private static final long EXIF_HEADER = 0x45786966; // Exif
   private static final int MARKER_SOI = 0xFFD8; // Start of image marker
   private static final int MARKER_SOS = 0xFFDA; // Start of scan (image data) marker
   private static final int MARKER_APP0 = 0xFFE0; // Application data 0 marker
   private static final int MARKER_APP1 = 0xFFE1; // Application data 1 marker
   private static final String HEADER_XMP_APP1 = "http://ns.adobe.com/xap/1.0/";

   /**
    * The identifier to use for the image track. Chosen to avoid colliding with track IDs used by
    * {@link Mp4Extractor} for motion photos.
    */
   private static final int IMAGE_TRACK_ID = 1024;

   private final ParsableByteArray scratch;

   private @MonotonicNonNull ExtractorOutput extractorOutput;

   @State private int state;
   private int marker;
   private int segmentLength;
   private long mp4StartPosition;

   @Nullable private MotionPhotoMetadata motionPhotoMetadata;
   private @MonotonicNonNull ExtractorInput lastExtractorInput;
   private @MonotonicNonNull StartOffsetExtractorInput mp4ExtractorStartOffsetExtractorInput;
   @Nullable private Mp4Extractor mp4Extractor;

   public JpegExtractor() {
     scratch = new ParsableByteArray(EXIF_ID_CODE_LENGTH);
     mp4StartPosition = C.POSITION_UNSET;
   }

   @Override
   public boolean sniff(ExtractorInput input) throws IOException {
     // See ITU-T.81 (1992) subsection B.1.1.3 and Exif version 2.2 (2002) subsection 4.5.4.
     if (peekMarker(input) != MARKER_SOI) {
       return false;
     }
     marker = peekMarker(input);
     // Even though JFIF and Exif standards are incompatible in theory, Exif files often contain a
     // JFIF APP0 marker segment preceding the Exif APP1 marker segment. Skip the JFIF segment if
     // present.
     if (marker == MARKER_APP0) {
       advancePeekPositionToNextSegment(input);
       marker = peekMarker(input);
     }
     if (marker != MARKER_APP1) {
       return false;
     }
     input.advancePeekPosition(2); // Unused segment length
     scratch.reset(/* limit= */ EXIF_ID_CODE_LENGTH);
     input.peekFully(scratch.getData(), /* offset= */ 0, EXIF_ID_CODE_LENGTH);
     return scratch.readUnsignedInt() == EXIF_HEADER && scratch.readUnsignedShort() == 0; // Exif\0\0
   }

   @Override
   public void init(ExtractorOutput output) {
     extractorOutput = output;
   }

   @Override
   @ReadResult
   public int read(ExtractorInput input, PositionHolder seekPosition) throws IOException {
     switch (state) {
       case STATE_READING_MARKER:
         readMarker(input);
         return RESULT_CONTINUE;
       case STATE_READING_SEGMENT_LENGTH:
         readSegmentLength(input);
         return RESULT_CONTINUE;
       case STATE_READING_SEGMENT:
         readSegment(input);
         return RESULT_CONTINUE;
       case STATE_SNIFFING_MOTION_PHOTO_VIDEO:
         if (input.getPosition() != mp4StartPosition) {
           seekPosition.position = mp4StartPosition;
           return RESULT_SEEK;
         }
         sniffMotionPhotoVideo(input);
         return RESULT_CONTINUE;
       case STATE_READING_MOTION_PHOTO_VIDEO:
         if (mp4ExtractorStartOffsetExtractorInput == null || input != lastExtractorInput) {
           lastExtractorInput = input;
           mp4ExtractorStartOffsetExtractorInput =
               new StartOffsetExtractorInput(input, mp4StartPosition);
         }
         @ReadResult
         int readResult =
             checkNotNull(mp4Extractor).read(mp4ExtractorStartOffsetExtractorInput, seekPosition);
         if (readResult == RESULT_SEEK) {
           seekPosition.position += mp4StartPosition;
         }
         return readResult;
       case STATE_ENDED:
         return RESULT_END_OF_INPUT;
       default:
         throw new IllegalStateException();
     }
   }

   @Override
   public void seek(long position, long timeUs) {
     if (position == 0) {
       state = STATE_READING_MARKER;
       mp4Extractor = null;
     } else if (state == STATE_READING_MOTION_PHOTO_VIDEO) {
       checkNotNull(mp4Extractor).seek(position, timeUs);
     }
   }

   @Override
   public void release() {
     if (mp4Extractor != null) {
       mp4Extractor.release();
     }
   }

   private int peekMarker(ExtractorInput input) throws IOException {
     scratch.reset(/* limit= */ 2);
     input.peekFully(scratch.getData(), /* offset= */ 0, /* length= */ 2);
     return scratch.readUnsignedShort();
   }

   private void advancePeekPositionToNextSegment(ExtractorInput input) throws IOException {
     scratch.reset(/* limit= */ 2);
     input.peekFully(scratch.getData(), /* offset= */ 0, /* length= */ 2);
     int segmentLength = scratch.readUnsignedShort() - 2;
     input.advancePeekPosition(segmentLength);
   }

   private void readMarker(ExtractorInput input) throws IOException {
     scratch.reset(/* limit= */ 2);
     input.readFully(scratch.getData(), /* offset= */ 0, /* length= */ 2);
     marker = scratch.readUnsignedShort();
     if (marker == MARKER_SOS) { // Start of scan.
       if (mp4StartPosition != C.POSITION_UNSET) {
         state = STATE_SNIFFING_MOTION_PHOTO_VIDEO;
       } else {
         endReadingWithImageTrack();
       }
     } else if ((marker < 0xFFD0 || marker > 0xFFD9) && marker != 0xFF01) {
       state = STATE_READING_SEGMENT_LENGTH;
     }
   }

   private void readSegmentLength(ExtractorInput input) throws IOException {
     scratch.reset(2);
     input.readFully(scratch.getData(), /* offset= */ 0, /* length= */ 2);
     segmentLength = scratch.readUnsignedShort() - 2;
     state = STATE_READING_SEGMENT;
   }

   private void readSegment(ExtractorInput input) throws IOException {
     if (marker == MARKER_APP1) {
       ParsableByteArray payload = new ParsableByteArray(segmentLength);
       input.readFully(payload.getData(), /* offset= */ 0, /* length= */ segmentLength);
       if (motionPhotoMetadata == null
           && HEADER_XMP_APP1.equals(payload.readNullTerminatedString())) {
         @Nullable String xmpString = payload.readNullTerminatedString();
         if (xmpString != null) {
           motionPhotoMetadata = getMotionPhotoMetadata(xmpString, input.getLength());
           if (motionPhotoMetadata != null) {
             mp4StartPosition = motionPhotoMetadata.videoStartPosition;
           }
         }
       }
     } else {
       input.skipFully(segmentLength);
     }
     state = STATE_READING_MARKER;
   }

   private void sniffMotionPhotoVideo(ExtractorInput input) throws IOException {
     // Check if the file is truncated.
     boolean peekedData =
         input.peekFully(
             scratch.getData(), /* offset= */ 0, /* length= */ 1, /* allowEndOfInput= */ true);
     if (!peekedData) {
       endReadingWithImageTrack();
     } else {
       input.resetPeekPosition();
       if (mp4Extractor == null) {
         mp4Extractor = new Mp4Extractor();
       }
       mp4ExtractorStartOffsetExtractorInput =
           new StartOffsetExtractorInput(input, mp4StartPosition);
       if (mp4Extractor.sniff(mp4ExtractorStartOffsetExtractorInput)) {
         mp4Extractor.init(
             new StartOffsetExtractorOutput(mp4StartPosition, checkNotNull(extractorOutput)));
         startReadingMotionPhoto();
       } else {
         endReadingWithImageTrack();
       }
     }
   }

   private void startReadingMotionPhoto() {
     outputImageTrack(checkNotNull(motionPhotoMetadata));
     state = STATE_READING_MOTION_PHOTO_VIDEO;
   }

   private void endReadingWithImageTrack() {
     outputImageTrack();
     checkNotNull(extractorOutput).endTracks();
     extractorOutput.seekMap(new SeekMap.Unseekable(/* durationUs= */ C.TIME_UNSET));
     state = STATE_ENDED;
   }

   private void outputImageTrack(Metadata.Entry... metadataEntries) {
     TrackOutput imageTrackOutput =
         checkNotNull(extractorOutput).track(IMAGE_TRACK_ID, C.TRACK_TYPE_IMAGE);
     imageTrackOutput.format(
         new Format.Builder()
             .setContainerMimeType(MimeTypes.IMAGE_JPEG)
             .setMetadata(new Metadata(metadataEntries))
             .build());
   }

   /**
    * Attempts to parse the specified XMP data describing the motion photo, returning the resulting
    * {@link MotionPhotoMetadata} or {@code null} if it wasn't possible to derive motion photo
    * metadata.
    *
    * @param xmpString A string of XML containing XMP motion photo metadata to attempt to parse.
    * @param inputLength The length of the input stream in bytes, or {@link C#LENGTH_UNSET} if
    *     unknown.
    * @return The {@link MotionPhotoMetadata}, or {@code null} if it wasn't possible to derive motion
    *     photo metadata.
    * @throws IOException If an error occurs parsing the XMP string.
    */
   @Nullable
   private static MotionPhotoMetadata getMotionPhotoMetadata(String xmpString, long inputLength)
       throws IOException {
     // Metadata defines offsets from the end of the stream, so we need the stream length to
     // determine start offsets.
     if (inputLength == C.LENGTH_UNSET) {
       return null;
     }

     // Motion photos have (at least) a primary image media item and a secondary video media item.
     @Nullable
     MotionPhotoDescription motionPhotoDescription =
         XmpMotionPhotoDescriptionParser.parse(xmpString);
     if (motionPhotoDescription == null) {
       return null;
     }
     return motionPhotoDescription.getMotionPhotoMetadata(inputLength);
   }
 }
	/*
	* Copyright 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.
	*/
	package com.google.android.exoplayer2.extractor.jpeg;

	import static com.google.android.exoplayer2.util.Assertions.checkNotNull;

	import androidx.annotation.IntDef;
	import androidx.annotation.Nullable;
	import com.google.android.exoplayer2.C;
	import com.google.android.exoplayer2.Format;
	import com.google.android.exoplayer2.extractor.Extractor;
	import com.google.android.exoplayer2.extractor.ExtractorInput;
	import com.google.android.exoplayer2.extractor.ExtractorOutput;
	import com.google.android.exoplayer2.extractor.PositionHolder;
	import com.google.android.exoplayer2.extractor.SeekMap;
	import com.google.android.exoplayer2.extractor.TrackOutput;
	import com.google.android.exoplayer2.extractor.mp4.Mp4Extractor;
	import com.google.android.exoplayer2.metadata.Metadata;
	import com.google.android.exoplayer2.metadata.mp4.MotionPhotoMetadata;
	import com.google.android.exoplayer2.util.MimeTypes;
	import com.google.android.exoplayer2.util.ParsableByteArray;
	import java.io.IOException;
	import java.lang.annotation.Documented;
	import java.lang.annotation.Retention;
	import java.lang.annotation.RetentionPolicy;
	import org.checkerframework.checker.nullness.qual.MonotonicNonNull;

	/** Extracts JPEG image using the Exif format. */
	public final class JpegExtractor implements Extractor {

	/** Parser states. */
	@Documented
	@Retention(RetentionPolicy.SOURCE)
	@IntDef({
	STATE_READING_MARKER,
	STATE_READING_SEGMENT_LENGTH,
	STATE_READING_SEGMENT,
	STATE_SNIFFING_MOTION_PHOTO_VIDEO,
	STATE_READING_MOTION_PHOTO_VIDEO,
	STATE_ENDED,
	})
	private @interface State {}

	private static final int STATE_READING_MARKER = 0;
	private static final int STATE_READING_SEGMENT_LENGTH = 1;
	private static final int STATE_READING_SEGMENT = 2;
	private static final int STATE_SNIFFING_MOTION_PHOTO_VIDEO = 4;
	private static final int STATE_READING_MOTION_PHOTO_VIDEO = 5;
	private static final int STATE_ENDED = 6;

	private static final int EXIF_ID_CODE_LENGTH = 6;
	private static final long EXIF_HEADER = 0x45786966; // Exif
	private static final int MARKER_SOI = 0xFFD8; // Start of image marker
	private static final int MARKER_SOS = 0xFFDA; // Start of scan (image data) marker
	private static final int MARKER_APP0 = 0xFFE0; // Application data 0 marker
	private static final int MARKER_APP1 = 0xFFE1; // Application data 1 marker
	private static final String HEADER_XMP_APP1 = "http://ns.adobe.com/xap/1.0/";

	/**
	* The identifier to use for the image track. Chosen to avoid colliding with track IDs used by
	* {@link Mp4Extractor} for motion photos.
	*/
	private static final int IMAGE_TRACK_ID = 1024;

	private final ParsableByteArray scratch;

	private @MonotonicNonNull ExtractorOutput extractorOutput;

	@State private int state;
	private int marker;
	private int segmentLength;
	private long mp4StartPosition;

	@Nullable private MotionPhotoMetadata motionPhotoMetadata;
	private @MonotonicNonNull ExtractorInput lastExtractorInput;
	private @MonotonicNonNull StartOffsetExtractorInput mp4ExtractorStartOffsetExtractorInput;
	@Nullable private Mp4Extractor mp4Extractor;

	public JpegExtractor() {
	scratch = new ParsableByteArray(EXIF_ID_CODE_LENGTH);
	mp4StartPosition = C.POSITION_UNSET;
	}

	@Override
	public boolean sniff(ExtractorInput input) throws IOException {
	// See ITU-T.81 (1992) subsection B.1.1.3 and Exif version 2.2 (2002) subsection 4.5.4.
	if (peekMarker(input) != MARKER_SOI) {
	return false;
	}
	marker = peekMarker(input);
	// Even though JFIF and Exif standards are incompatible in theory, Exif files often contain a
	// JFIF APP0 marker segment preceding the Exif APP1 marker segment. Skip the JFIF segment if
	// present.
	if (marker == MARKER_APP0) {
	advancePeekPositionToNextSegment(input);
	marker = peekMarker(input);
	}
	if (marker != MARKER_APP1) {
	return false;
	}
	input.advancePeekPosition(2); // Unused segment length
	scratch.reset(/* limit= */ EXIF_ID_CODE_LENGTH);
	input.peekFully(scratch.getData(), /* offset= */ 0, EXIF_ID_CODE_LENGTH);
	return scratch.readUnsignedInt() == EXIF_HEADER && scratch.readUnsignedShort() == 0; // Exif\0\0
	}

	@Override
	public void init(ExtractorOutput output) {
	extractorOutput = output;
	}

	@Override
	@ReadResult
	public int read(ExtractorInput input, PositionHolder seekPosition) throws IOException {
	switch (state) {
	case STATE_READING_MARKER:
	readMarker(input);
	return RESULT_CONTINUE;
	case STATE_READING_SEGMENT_LENGTH:
	readSegmentLength(input);
	return RESULT_CONTINUE;
	case STATE_READING_SEGMENT:
	readSegment(input);
	return RESULT_CONTINUE;
	case STATE_SNIFFING_MOTION_PHOTO_VIDEO:
	if (input.getPosition() != mp4StartPosition) {
	seekPosition.position = mp4StartPosition;
	return RESULT_SEEK;
	}
	sniffMotionPhotoVideo(input);
	return RESULT_CONTINUE;
	case STATE_READING_MOTION_PHOTO_VIDEO:
	if (mp4ExtractorStartOffsetExtractorInput == null \|\| input != lastExtractorInput) {
	lastExtractorInput = input;
	mp4ExtractorStartOffsetExtractorInput =
	new StartOffsetExtractorInput(input, mp4StartPosition);
	}
	@ReadResult
	int readResult =
	checkNotNull(mp4Extractor).read(mp4ExtractorStartOffsetExtractorInput, seekPosition);
	if (readResult == RESULT_SEEK) {
	seekPosition.position += mp4StartPosition;
	}
	return readResult;
	case STATE_ENDED:
	return RESULT_END_OF_INPUT;
	default:
	throw new IllegalStateException();
	}
	}

	@Override
	public void seek(long position, long timeUs) {
	if (position == 0) {
	state = STATE_READING_MARKER;
	mp4Extractor = null;
	} else if (state == STATE_READING_MOTION_PHOTO_VIDEO) {
	checkNotNull(mp4Extractor).seek(position, timeUs);
	}
	}

	@Override
	public void release() {
	if (mp4Extractor != null) {
	mp4Extractor.release();
	}
	}

	private int peekMarker(ExtractorInput input) throws IOException {
	scratch.reset(/* limit= */ 2);
	input.peekFully(scratch.getData(), /* offset= / 0, / length= */ 2);
	return scratch.readUnsignedShort();
	}

	private void advancePeekPositionToNextSegment(ExtractorInput input) throws IOException {
	scratch.reset(/* limit= */ 2);
	input.peekFully(scratch.getData(), /* offset= / 0, / length= */ 2);
	int segmentLength = scratch.readUnsignedShort() - 2;
	input.advancePeekPosition(segmentLength);
	}

	private void readMarker(ExtractorInput input) throws IOException {
	scratch.reset(/* limit= */ 2);
	input.readFully(scratch.getData(), /* offset= / 0, / length= */ 2);
	marker = scratch.readUnsignedShort();
	if (marker == MARKER_SOS) { // Start of scan.
	if (mp4StartPosition != C.POSITION_UNSET) {
	state = STATE_SNIFFING_MOTION_PHOTO_VIDEO;
	} else {
	endReadingWithImageTrack();
	}
	} else if ((marker < 0xFFD0 \|\| marker > 0xFFD9) && marker != 0xFF01) {
	state = STATE_READING_SEGMENT_LENGTH;
	}
	}

	private void readSegmentLength(ExtractorInput input) throws IOException {
	scratch.reset(2);
	input.readFully(scratch.getData(), /* offset= / 0, / length= */ 2);
	segmentLength = scratch.readUnsignedShort() - 2;
	state = STATE_READING_SEGMENT;
	}

	private void readSegment(ExtractorInput input) throws IOException {
	if (marker == MARKER_APP1) {
	ParsableByteArray payload = new ParsableByteArray(segmentLength);
	input.readFully(payload.getData(), /* offset= / 0, / length= */ segmentLength);
	if (motionPhotoMetadata == null
	&& HEADER_XMP_APP1.equals(payload.readNullTerminatedString())) {
	@Nullable String xmpString = payload.readNullTerminatedString();
	if (xmpString != null) {
	motionPhotoMetadata = getMotionPhotoMetadata(xmpString, input.getLength());
	if (motionPhotoMetadata != null) {
	mp4StartPosition = motionPhotoMetadata.videoStartPosition;
	}
	}
	}
	} else {
	input.skipFully(segmentLength);
	}
	state = STATE_READING_MARKER;
	}

	private void sniffMotionPhotoVideo(ExtractorInput input) throws IOException {
	// Check if the file is truncated.
	boolean peekedData =
	input.peekFully(
	scratch.getData(), /* offset= / 0, / length= / 1, / allowEndOfInput= */ true);
	if (!peekedData) {
	endReadingWithImageTrack();
	} else {
	input.resetPeekPosition();
	if (mp4Extractor == null) {
	mp4Extractor = new Mp4Extractor();
	}
	mp4ExtractorStartOffsetExtractorInput =
	new StartOffsetExtractorInput(input, mp4StartPosition);
	if (mp4Extractor.sniff(mp4ExtractorStartOffsetExtractorInput)) {
	mp4Extractor.init(
	new StartOffsetExtractorOutput(mp4StartPosition, checkNotNull(extractorOutput)));
	startReadingMotionPhoto();
	} else {
	endReadingWithImageTrack();
	}
	}
	}

	private void startReadingMotionPhoto() {
	outputImageTrack(checkNotNull(motionPhotoMetadata));
	state = STATE_READING_MOTION_PHOTO_VIDEO;
	}

	private void endReadingWithImageTrack() {
	outputImageTrack();
	checkNotNull(extractorOutput).endTracks();
	extractorOutput.seekMap(new SeekMap.Unseekable(/* durationUs= */ C.TIME_UNSET));
	state = STATE_ENDED;
	}

	private void outputImageTrack(Metadata.Entry... metadataEntries) {
	TrackOutput imageTrackOutput =
	checkNotNull(extractorOutput).track(IMAGE_TRACK_ID, C.TRACK_TYPE_IMAGE);
	imageTrackOutput.format(
	new Format.Builder()
	.setContainerMimeType(MimeTypes.IMAGE_JPEG)
	.setMetadata(new Metadata(metadataEntries))
	.build());
	}

	/**
	* Attempts to parse the specified XMP data describing the motion photo, returning the resulting
	* {@link MotionPhotoMetadata} or {@code null} if it wasn't possible to derive motion photo
	* metadata.
	*
	* @param xmpString A string of XML containing XMP motion photo metadata to attempt to parse.
	* @param inputLength The length of the input stream in bytes, or {@link C#LENGTH_UNSET} if
	* unknown.
	* @return The {@link MotionPhotoMetadata}, or {@code null} if it wasn't possible to derive motion
	* photo metadata.
	* @throws IOException If an error occurs parsing the XMP string.
	*/
	@Nullable
	private static MotionPhotoMetadata getMotionPhotoMetadata(String xmpString, long inputLength)
	throws IOException {
	// Metadata defines offsets from the end of the stream, so we need the stream length to
	// determine start offsets.
	if (inputLength == C.LENGTH_UNSET) {
	return null;
	}

	// Motion photos have (at least) a primary image media item and a secondary video media item.
	@Nullable
	MotionPhotoDescription motionPhotoDescription =
	XmpMotionPhotoDescriptionParser.parse(xmpString);
	if (motionPhotoDescription == null) {
	return null;
	}
	return motionPhotoDescription.getMotionPhotoMetadata(inputLength);
	}
	}