NIFF XML Proposal

This is a proposed XML schema for encoding NIFF files in XML, with an effort to unify it with Gerd Castan's NIFFML. Once unified, I expect that this would live on Gerd Castan's web site.

An XML file is useful because it is easier to read and modify by a human, and a good XML editor, in combination with the NIFF XML schema, can let a user directly encode a NIFF file, which is especially useful for learning how to use NIFF.

The NIFFML.xsd schema for XML. (right-click and choose Save Target As)

Try It with XML Doctor

To see how you can work with a NIFF XML file in a smart XML editor, try XML Doctor for Windows:

Download and run XML Doctor Setup
Download and put simple.xml and NIFFML.xsd in the same folder. (right-click and choose Save Target As)
Run XML Doctor and open simple.xml
You can use simple.xml as a starting point to edit your own NIFF XML file

Here is how the NIFF file simple.nif converted to simple.xml looks in XML Doctor:

Also, here is a much larger example of a NIFF XML file:

AFTER.NIFFML-rev3.xml (660 KB) (right-click and choose Save Target As)

Notes on NIFF Binary vs. XML

The main NIFF specification is for a binary file format. Here are some notes on how the XML format differs from the binary format, especially for developers who want to convert between the two.

Integer Type vs. SHORT, BYTE etc.

The binary file format uses SHORT, BYTE, SIGNEDBYTE, etc. But NIFF XML generally just uses the Schema integer type since the choice between SHORT, BYTE etc. is mainly a space-saving encoding issue for the binary file format.

Chunk Length Table

The Chunk Length Table provides details on how the particular binary NIFF file containg the table encodes chunks. Because NIFF XML does not encode chunks in binary, it does not have a Chunk Length Table. A NIFF XML to binary file converter application can suppy its own Chunk Length Table based on the encoding it is using at the time.

String Length Table

The String Length Table is used by the integer STROFFSET string offset to find the corresponding string. NIFF 6b also describes how a Unicode string can also be provided for the same STROFFSET. The String Length Table is necessary because the binary RIFF encoding doesn't provide an easy way to embed a string within a chunk. XML, however, can easily put a string attribute anywhere. And XML has native support for Unicode, so there is no need for a separate mechanism for Unicode. Therefore, NIFF XML doesn't have a String Length Table. And instead of STROFFSET, NIFF XML just uses an optional string attribute. A STROFFSET of -1 for an empty string corresponds to omitting the string attribute. A NIFF XML to binary file converter application can create its own String Length Table at the time of encoding.

The RATIONAL type

The NIFF binary RATIONAL type is represented as two separate integer attrivutes for the numerator and denominator. For example, the RATIONAL duration in the Notehead chunk is represented as two attributes "durationN" and "durationD".

Tags in NIFF XML

As with Gerd Castan's NIFFML, each tag is represented as a child element of the chunk element. An advantage is that the Schema lists only the child tag elements which each chunk element allows. It should be fairly obvious which element name corresponds to which tag, e.g. AbsolutePlacement for the absolute placement tag 0x01. The "ID" tag 0x12 is called MultiNodeID because "ID" is too general of a name.

Key Signature standard code

In the Key Signature chunk, NIFF binary uses a "standard code" number which is an integer that encodes the number of sharps, flats or naturals. As with many other places in NIFF XML, each possible integer value is represented by the string which it means. In this case, "1 sharp", "2 sharps", etc. This is much easier for the user when working with the NIFF data in the XML editor, and there is an exact one-to-one correspondence between each string and the integer it represents.

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