content: /*
   * Copyright 2002-2019 Drew Noakes and contributors
   *
   *    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
   *
   *        https://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.
   *
   * More information about this project is available at:
   *
   *    https://drewnoakes.com/code/exif/
   *    https://github.com/drewnoakes/metadata-extractor
   */
  package com.drew.imaging.mp4;
  
  import com.drew.lang.StreamReader;
  import com.drew.lang.annotations.NotNull;
  import com.drew.metadata.mp4.Mp4Context;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * @author Payton Garland
   */
  public class Mp4Reader
  {
      private Mp4Reader() {}
  
      public static void extract(@NotNull InputStream inputStream, @NotNull Mp4Handler<?> handler)
      {
          StreamReader reader = new StreamReader(inputStream);
          reader.setMotorolaByteOrder(true);
  
          Mp4Context context = new Mp4Context();
  
          processBoxes(reader, -1, handler, context);
      }
  
      private static void processBoxes(StreamReader reader, long atomEnd, Mp4Handler<?> handler, Mp4Context context)
      {
          try {
              while (atomEnd == -1 || reader.getPosition() < atomEnd) {
  
                  long boxSize = reader.getUInt32();
  
                  String boxType = reader.getString(4);
  
                  boolean isLargeSize = boxSize == 1;
  
                  if (isLargeSize) {
                      boxSize = reader.getInt64();
                  }
  
                  if (boxSize > Integer.MAX_VALUE) {
                      handler.addError("Box size too large.");
                      break;
                  }
  
                  if (boxSize < 8) {
                      handler.addError("Box size too small.");
                      break;
                  }
  
                  // Determine if fourCC is container/atom and process accordingly.
                  // Unknown atoms will be skipped
  
                  if (handler.shouldAcceptContainer(boxType)) {
                      // Recur, to process nested boxes within container box
                      processBoxes(reader, boxSize + reader.getPosition() - 8, handler.processContainer(boxType, boxSize, context), context);
                  } else if (handler.shouldAcceptBox(boxType)) {
                      handler = handler.processBox(boxType, reader.getBytes((int)boxSize - 8), boxSize, context);
                  } else if (isLargeSize) {
                      if (boxSize < 16) {
                          // TODO capture this error in a directory
                          break;
                      }
                      reader.skip(boxSize - 16);
                  } else {
                      reader.skip(boxSize - 8);
                  }
              }
          } catch (IOException e) {
              handler.addError(e.getMessage());
          }
      }
  }
  