Mp4HdlrBox.java

package org.jaudiotagger.audio.mp4.atom;

import org.jaudiotagger.audio.exceptions.CannotReadException;
import org.jaudiotagger.audio.mp4.Mp4NotMetaFieldKey;

import java.nio.ByteBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.util.HashMap;
import java.util.Map;

/**
 * HdlrBox ( Handler box),
 * <p/>
 * Describes the type of metadata in the following ilst or minf atom
 */
public class Mp4HdlrBox extends AbstractMp4Box {
    public static final int VERSION_FLAG_LENGTH = 1;
    public static final int OTHER_FLAG_LENGTH = 3;
    public static final int RESERVED_FLAG_LENGTH = 4;
    public static final int HANDLER_LENGTH = 4;
    public static final int RESERVED1_LENGTH = 4;
    public static final int RESERVED2_LENGTH = 4;
    public static final int RESERVED3_LENGTH = 4;
    public static final int NAME_LENGTH = 2;

    public static final int HANDLER_POS = VERSION_FLAG_LENGTH + OTHER_FLAG_LENGTH + RESERVED_FLAG_LENGTH;
    public static final int RESERVED1_POS = HANDLER_POS + HANDLER_LENGTH;

    //Size used by iTunes, but other application could use different size because name field is variable
    public static final int ITUNES_META_HDLR_DAT_LENGTH =
            VERSION_FLAG_LENGTH +
                    OTHER_FLAG_LENGTH +
                    RESERVED_FLAG_LENGTH +
                    HANDLER_LENGTH +
                    RESERVED1_LENGTH +
                    RESERVED2_LENGTH +
                    RESERVED3_LENGTH +
                    NAME_LENGTH;


    private int reserved;        // 32 bit
    private String handlerType;     // 4 bytes;
    private String name;            // Variable length but 4 bytes in existing files
    private MediaDataType mediaDataType;

    private static Map<String, MediaDataType> mediaDataTypeMap;

    static {
        //Create maps to speed up lookup from raw value to enum
        mediaDataTypeMap = new HashMap<String, MediaDataType>();
        for (MediaDataType next : MediaDataType.values()) {
            mediaDataTypeMap.put(next.getId(), next);
        }
    }

    /**
     * DataBuffer must start from from the start of the body
     *
     * @param header     header info
     * @param dataBuffer data of box (doesnt include header data)
     */
    public Mp4HdlrBox(Mp4BoxHeader header, ByteBuffer dataBuffer) {
        this.header = header;
        this.dataBuffer = dataBuffer;
    }

    public void processData() throws CannotReadException {
        //Skip other flags
        dataBuffer.position(dataBuffer.position() + VERSION_FLAG_LENGTH + OTHER_FLAG_LENGTH + RESERVED_FLAG_LENGTH);


        CharsetDecoder decoder = Charset.forName("ISO-8859-1").newDecoder();
        try {
            handlerType = decoder.decode((ByteBuffer) dataBuffer.slice().limit(HANDLER_LENGTH)).toString();
        } catch (CharacterCodingException cee) {
            //Ignore

        }

        //To getFields human readable name
        mediaDataType = mediaDataTypeMap.get(handlerType);
    }

    public String getHandlerType() {
        return handlerType;
    }

    public MediaDataType getMediaDataType() {
        return mediaDataType;
    }

    public String toString() {
        String s = "handlerType:" + handlerType + ":human readable:" + mediaDataType.getDescription();
        return s;
    }

    public static enum MediaDataType {
        ODSM("odsm", "ObjectDescriptorStream - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),
        CRSM("crsm", "ClockReferenceStream - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),
        SDSM("sdsm", "SceneDescriptionStream - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),
        M7SM("m7sm", "MPEG7Stream - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),
        OCSM("ocsm", "ObjectContentInfoStream - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),
        IPSM("ipsm", "IPMP Stream - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),
        MJSM("mjsm", "MPEG-J Stream - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),
        MDIR("mdir", "Apple Meta Data iTunes Reader"),
        MP7B("mp7b", "MPEG-7 binary XML"),
        MP7T("mp7t", "MPEG-7 XML"),
        VIDE("vide", "Video Track"),
        SOUN("soun", "Sound Track"),
        HINT("hint", "Hint Track"),
        APPL("appl", "Apple specific"),
        META("meta", "Timed Metadata track - defined in ISO/IEC JTC1/SC29/WG11 - CODING OF MOVING PICTURES AND AUDIO"),;

        private String id;
        private String description;


        MediaDataType(String id, String description) {
            this.id = id;
            this.description = description;
        }

        public String getId() {
            return id;
        }

        public String getDescription() {
            return description;
        }
    }

    /**
     * Create an iTunes style Hdlr box for use within Meta box
     * <p/>
     * <p>Useful when writing to mp4 that previously didn't contain an mp4 meta atom</p>
     * <p/>
     * <p>Doesnt write the child data but uses it to se the header length, only sets the atoms immediate
     * data</p
     *
     * @return
     */
    public static Mp4HdlrBox createiTunesStyleHdlrBox() {
        Mp4BoxHeader hdlrHeader = new Mp4BoxHeader(Mp4NotMetaFieldKey.HDLR.getFieldName());
        hdlrHeader.setLength(Mp4BoxHeader.HEADER_LENGTH + Mp4HdlrBox.ITUNES_META_HDLR_DAT_LENGTH);

        ByteBuffer hdlrData = ByteBuffer.allocate(Mp4HdlrBox.ITUNES_META_HDLR_DAT_LENGTH);
        hdlrData.put(HANDLER_POS, (byte) 0x6d);       //mdir
        hdlrData.put(HANDLER_POS + 1, (byte) 0x64);
        hdlrData.put(HANDLER_POS + 2, (byte) 0x69);
        hdlrData.put(HANDLER_POS + 3, (byte) 0x72);
        hdlrData.put(RESERVED1_POS, (byte) 0x61);          //appl
        hdlrData.put(RESERVED1_POS + 1, (byte) 0x70);
        hdlrData.put(RESERVED1_POS + 2, (byte) 0x70);
        hdlrData.put(RESERVED1_POS + 3, (byte) 0x6c);
        hdlrData.rewind();

        Mp4HdlrBox hdlrBox = new Mp4HdlrBox(hdlrHeader, hdlrData);
        return hdlrBox;
    }
}