FileDocCategorySizeDatePackage
Mp4TagCreator.javaAPI DocJaudiotagger 2.0.46121Thu Sep 22 10:42:54 BST 2011org.jaudiotagger.tag.mp4

Mp4TagCreator

public class Mp4TagCreator extends org.jaudiotagger.audio.generic.AbstractTagCreator
Create raw content of mp4 tag data, concerns itself with atoms upto the ilst atom

This level is was selected because the ilst atom can be recreated without reference to existing mp4 fields but fields above this level are dependent upon other information that is not held in the tag. 

|--- ftyp
|--- moov
|......|
|......|----- mvdh
|......|----- trak
|......|----- udta
|..............|
|..............|-- meta
|....................|
|....................|-- hdlr
|....................|-- ilst
|....................|.. ..|
|....................|.....|---- @nam (Optional for each metadatafield)
|....................|.....|.......|-- data
|....................|.....|....... ecetera
|....................|.....|---- ---- (Optional for reverse dns field)
|....................|.............|-- mean
|....................|.............|-- name
|....................|.............|-- data
|....................|................ ecetere
|....................|-- free
|--- free
|--- mdat

Fields Summary
Constructors Summary
Methods Summary
public java.nio.ByteBufferconvert(org.jaudiotagger.tag.Tag tag, int padding)
Convert tagdata to rawdata ready for writing to file

param
tag
param
padding TODO padding parameter currently ignored
return
throws
UnsupportedEncodingException

        try
        {
            //Add metadata raw content
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            Iterator<TagField> it = tag.getFields();
            boolean processedArtwork = false;
            while (it.hasNext())
            {
                TagField frame = it.next();
                //To ensure order is maintained dont process artwork until iterator hits it.
                if (frame instanceof Mp4TagCoverField)
                {
                    if (processedArtwork)
                    {
                        //ignore
                    }
                    else
                    {
                        processedArtwork = true;

                        //Because each artwork image is held within the tag as a separate field, but when
                        //they are written they are all held under a single covr box we need to do some checks
                        //and special processing here if we have any artwork image (this code only necessary
                        //if we have more than 1 but do it anyway even if only have 1 image)
                        ByteArrayOutputStream covrDataBaos = new ByteArrayOutputStream();

                        try
                        {
                            for (TagField artwork : tag.getFields(FieldKey.COVER_ART))
                            {
                                covrDataBaos.write(((Mp4TagField) artwork).getRawContentDataOnly());
                            }
                        }
                        catch (KeyNotFoundException knfe)
                        {
                            //This cannot happen
                            throw new RuntimeException("Unable to find COVERART Key");
                        }

                        //Now create the parent Data
                        byte[] data = covrDataBaos.toByteArray();
                        baos.write(Utils.getSizeBEInt32(Mp4BoxHeader.HEADER_LENGTH + data.length));
                        baos.write(Utils.getDefaultBytes(Mp4FieldKey.ARTWORK.getFieldName(), "ISO-8859-1"));
                        baos.write(data);
                    }
                }
                else
                {                     
                    baos.write(frame.getRawContent());
                }
            }

            //Wrap into ilst box
            ByteArrayOutputStream ilst = new ByteArrayOutputStream();
            ilst.write(Utils.getSizeBEInt32(Mp4BoxHeader.HEADER_LENGTH + baos.size()));
            ilst.write(Utils.getDefaultBytes(Mp4AtomIdentifier.ILST.getFieldName(), "ISO-8859-1"));
            ilst.write(baos.toByteArray());

            //Put into ByteBuffer
            ByteBuffer buf = ByteBuffer.wrap(ilst.toByteArray());
            buf.rewind();
            return buf;
        }
        catch (IOException ioe)
        {
            //Should never happen as not writing to file at this point
            throw new RuntimeException(ioe);
        }