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A generic parser and writer for all ISO 14496 based files (MP4, Quicktime, DCF, PDCF, ...)

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/*  
 * Copyright 2008 CoreMedia AG, Hamburg
 *
 * 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.coremedia.iso.boxes.mdat;

import com.coremedia.iso.BoxParser;
import com.coremedia.iso.boxes.Box;
import com.coremedia.iso.boxes.Container;

import java.io.IOException;
import java.nio.ByteBuffer;

import com.googlecode.mp4parser.DataSource;

import java.nio.channels.WritableByteChannel;
import java.util.logging.Logger;

/**
 * 

4cc = "{@value #TYPE}"

* This box contains the media data. In video tracks, this box would contain video frames. A presentation may * contain zero or more Media Data Boxes. The actual media data follows the type field; its structure is described * by the metadata (see {@link com.coremedia.iso.boxes.SampleTableBox}).
* In large presentations, it may be desirable to have more data in this box than a 32-bit size would permit. In this * case, the large variant of the size field is used.
* There may be any number of these boxes in the file (including zero, if all the media data is in other files). The * metadata refers to media data by its absolute offset within the file (see {@link com.coremedia.iso.boxes.StaticChunkOffsetBox}); * so Media Data Box headers and free space may easily be skipped, and files without any box structure may * also be referenced and used. */ public final class MediaDataBox implements Box { public static final String TYPE = "mdat"; Container parent; // These fields are for the special case of a DataSource as input. private DataSource dataSource; private long offset; private long size; public Container getParent() { return parent; } public void setParent(Container parent) { this.parent = parent; } public String getType() { return TYPE; } private static void transfer(DataSource from, long position, long count, WritableByteChannel to) throws IOException { long maxCount = (64 * 1024 * 1024) - (32 * 1024); // Transfer data in chunks a bit less than 64MB // People state that this is a kind of magic number on Windows. // I don't care. The size seems reasonable. long offset = 0; while (offset < count) { offset += from.transferTo(position + offset, Math.min(maxCount, count - offset), to); } } public void getBox(WritableByteChannel writableByteChannel) throws IOException { transfer(dataSource, offset, size, writableByteChannel); } public long getSize() { return size; } public long getOffset() { return offset; } public void parse(DataSource dataSource, ByteBuffer header, long contentSize, BoxParser boxParser) throws IOException { this.offset = dataSource.position() - header.remaining(); this.dataSource = dataSource; this.size = contentSize + header.remaining(); dataSource.position(dataSource.position() + contentSize); } @Override public String toString() { return "MediaDataBox{" + "size=" + size + '}'; } }




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