Mp4TagReaderpublic class Mp4TagReader extends Object | Reads metadata from mp4,
The metadata tags are usually held under the ilst atom as shown below
Valid Exceptions to the rule:
Can be no udta atom with meta rooted immediately under moov instead
Can be no udta/meta atom at all
|--- ftyp
|--- moov
|......|
|......|----- mvdh
|......|----- trak
|......|----- udta
|..............|
|..............|-- meta
|....................|
|....................|-- hdlr
|....................|-- ilst
|.........................|
|.........................|---- @nam (Optional for each metadatafield)
|.........................|.......|-- data
|.........................|....... ecetera
|.........................|---- ---- (Optional for reverse dns field)
|.................................|-- mean
|.................................|-- name
|.................................|-- data
|.................................... ecetere
|
|--- mdat
|
| Fields Summary |
|---|
| public static Logger | logger |
| Methods Summary |
|---|
| private void | createMp4Field(org.jaudiotagger.tag.mp4.Mp4Tag tag, org.jaudiotagger.audio.mp4.atom.Mp4BoxHeader header, java.nio.ByteBuffer raw)Process the field and add to the tag
Note:In the case of coverart MP4 holds all the coverart within individual dataitems all within
a single covr atom, we will add separate mp4field for each image.
//Reverse Dns Atom
if (header.getId().equals(Mp4TagReverseDnsField.IDENTIFIER))
{
//
try
{
TagField field = new Mp4TagReverseDnsField(header, raw);
tag.addField(field);
}
catch (Exception e)
{
logger.warning(ErrorMessage.MP4_UNABLE_READ_REVERSE_DNS_FIELD.getMsg(e.getMessage()));
TagField field = new Mp4TagRawBinaryField(header, raw);
tag.addField(field);
}
}
//Normal Parent with Data atom
else
{
int currentPos = raw.position();
boolean isDataIdentifier = Utils.getString(raw, Mp4BoxHeader.IDENTIFIER_POS, Mp4BoxHeader.IDENTIFIER_LENGTH, "ISO-8859-1").equals(Mp4DataBox.IDENTIFIER);
raw.position(currentPos);
if (isDataIdentifier)
{
//Need this to decide what type of Field to create
int type = Utils.getIntBE(raw, Mp4DataBox.TYPE_POS_INCLUDING_HEADER, Mp4DataBox.TYPE_POS_INCLUDING_HEADER + Mp4DataBox.TYPE_LENGTH - 1);
Mp4FieldType fieldType = Mp4FieldType.getFieldType(type);
logger.config("Box Type id:" + header.getId() + ":type:" + fieldType);
//Special handling for some specific identifiers otherwise just base on class id
if (header.getId().equals(Mp4FieldKey.TRACK.getFieldName()))
{
TagField field = new Mp4TrackField(header.getId(), raw);
tag.addField(field);
}
else if (header.getId().equals(Mp4FieldKey.DISCNUMBER.getFieldName()))
{
TagField field = new Mp4DiscNoField(header.getId(), raw);
tag.addField(field);
}
else if (header.getId().equals(Mp4FieldKey.GENRE.getFieldName()))
{
TagField field = new Mp4GenreField(header.getId(), raw);
tag.addField(field);
}
else if (header.getId().equals(Mp4FieldKey.ARTWORK.getFieldName()) || Mp4FieldType.isCoverArtType(fieldType))
{
int processedDataSize = 0;
int imageCount = 0;
//The loop should run for each image (each data atom)
while (processedDataSize < header.getDataLength())
{
//There maybe a mixture of PNG and JPEG images so have to check type
//for each subimage (if there are more than one image)
if (imageCount > 0)
{
type = Utils.getIntBE(raw, processedDataSize + Mp4DataBox.TYPE_POS_INCLUDING_HEADER,
processedDataSize + Mp4DataBox.TYPE_POS_INCLUDING_HEADER + Mp4DataBox.TYPE_LENGTH - 1);
fieldType = Mp4FieldType.getFieldType(type);
}
Mp4TagCoverField field = new Mp4TagCoverField(raw,fieldType);
tag.addField(field);
processedDataSize += field.getDataAndHeaderSize();
imageCount++;
}
}
else if (fieldType == Mp4FieldType.TEXT)
{
TagField field = new Mp4TagTextField(header.getId(), raw);
tag.addField(field);
}
else if (fieldType == Mp4FieldType.IMPLICIT)
{
TagField field = new Mp4TagTextNumberField(header.getId(), raw);
tag.addField(field);
}
else if (fieldType == Mp4FieldType.INTEGER)
{
TagField field = new Mp4TagByteField(header.getId(), raw);
tag.addField(field);
}
else
{
boolean existingId = false;
for (Mp4FieldKey key : Mp4FieldKey.values())
{
if (key.getFieldName().equals(header.getId()))
{
//The parentHeader is a known id but its field type is not one of the expected types so
//this field is invalid. i.e I received a file with the TMPO set to 15 (Oxf) when it should
//be 21 (ox15) so looks like somebody got their decimal and hex numbering confused
//So in this case best to ignore this field and just write a warning
existingId = true;
logger.warning("Known Field:" + header.getId() + " with invalid field type of:" + type + " is ignored");
break;
}
}
//Unknown field id with unknown type so just create as binary
if (!existingId)
{
logger.warning("UnKnown Field:" + header.getId() + " with invalid field type of:" + type + " created as binary");
TagField field = new Mp4TagBinaryField(header.getId(), raw);
tag.addField(field);
}
}
}
//Special Cases
else
{
//MediaMonkey 3 CoverArt Attributes field, does not have data items so just
//copy parent and child as is without modification
if (header.getId().equals(Mp4NonStandardFieldKey.AAPR.getFieldName()))
{
TagField field = new Mp4TagRawBinaryField(header, raw);
tag.addField(field);
}
//Default case
else
{
TagField field = new Mp4TagRawBinaryField(header, raw);
tag.addField(field);
}
}
}
| | public org.jaudiotagger.tag.mp4.Mp4Tag | read(java.io.RandomAccessFile raf)
/*
* The metadata is stored in the box under the hierachy moov.udta.meta.ilst
*
* There are gaps between these boxes
*/
Mp4Tag tag = new Mp4Tag();
//Get to the facts everything we are interested in is within the moov box, so just load data from file
//once so no more file I/O needed
Mp4BoxHeader moovHeader = Mp4BoxHeader.seekWithinLevel(raf, Mp4AtomIdentifier.MOOV.getFieldName());
if (moovHeader == null)
{
throw new CannotReadException(ErrorMessage.MP4_FILE_NOT_CONTAINER.getMsg());
}
ByteBuffer moovBuffer = ByteBuffer.allocate(moovHeader.getLength() - Mp4BoxHeader.HEADER_LENGTH);
raf.getChannel().read(moovBuffer);
moovBuffer.rewind();
//Level 2-Searching for "udta" within "moov"
Mp4BoxHeader boxHeader = Mp4BoxHeader.seekWithinLevel(moovBuffer, Mp4AtomIdentifier.UDTA.getFieldName());
if (boxHeader != null)
{
//Level 3-Searching for "meta" within udta
boxHeader = Mp4BoxHeader.seekWithinLevel(moovBuffer, Mp4AtomIdentifier.META.getFieldName());
if (boxHeader == null)
{
logger.warning(ErrorMessage.MP4_FILE_HAS_NO_METADATA.getMsg());
return tag;
}
Mp4MetaBox meta = new Mp4MetaBox(boxHeader, moovBuffer);
meta.processData();
//Level 4- Search for "ilst" within meta
boxHeader = Mp4BoxHeader.seekWithinLevel(moovBuffer, Mp4AtomIdentifier.ILST.getFieldName());
//This file does not actually contain a tag
if (boxHeader == null)
{
logger.warning(ErrorMessage.MP4_FILE_HAS_NO_METADATA.getMsg());
return tag;
}
}
else
{
//Level 2-Searching for "meta" not within udta
boxHeader = Mp4BoxHeader.seekWithinLevel(moovBuffer, Mp4AtomIdentifier.META.getFieldName());
if (boxHeader == null)
{
logger.warning(ErrorMessage.MP4_FILE_HAS_NO_METADATA.getMsg());
return tag;
}
Mp4MetaBox meta = new Mp4MetaBox(boxHeader, moovBuffer);
meta.processData();
//Level 3- Search for "ilst" within meta
boxHeader = Mp4BoxHeader.seekWithinLevel(moovBuffer, Mp4AtomIdentifier.ILST.getFieldName());
//This file does not actually contain a tag
if (boxHeader == null)
{
logger.warning(ErrorMessage.MP4_FILE_HAS_NO_METADATA.getMsg());
return tag;
}
}
//Size of metadata (exclude the size of the ilst parentHeader), take a slice starting at
//metadata children to make things safer
int length = boxHeader.getLength() - Mp4BoxHeader.HEADER_LENGTH;
ByteBuffer metadataBuffer = moovBuffer.slice();
//Datalength is longer are there boxes after ilst at this level?
logger.config("headerlengthsays:" + length + "datalength:" + metadataBuffer.limit());
int read = 0;
logger.config("Started to read metadata fields at position is in metadata buffer:" + metadataBuffer.position());
while (read < length)
{
//Read the boxHeader
boxHeader.update(metadataBuffer);
//Create the corresponding datafield from the id, and slice the buffer so position of main buffer
//wont get affected
logger.config("Next position is at:" + metadataBuffer.position());
createMp4Field(tag, boxHeader, metadataBuffer.slice());
//Move position in buffer to the start of the next parentHeader
metadataBuffer.position(metadataBuffer.position() + boxHeader.getDataLength());
read += boxHeader.getLength();
}
return tag;
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