Applying Descriptive Metadata in MXF (Material Exchange Format)

Applying Descriptive Metadata in MXF (Material Exchange Format)

SMPTE 380M "Material Exchange Format - Descriptive Metadata Scheme-1" has been out for years, but still not really widely used in the broadcasting industry. The most important reason is that there is not a clear specification of how to map the real world metadata to DMS1. One good example is the disscussion in the "MXF Expert" group of www.linkedin.com about how to use "Key frame" in MXF.

There are three common ways to carry Descriptive Metadata in MXF files.

1. Using non-referenced KLV (of course a unique key). An example is SONY XDCAM files. SONY puts their XML metadata in to MXF file as a KLV chunk, which is not referenced (linked) by any other KLVs in the file. This actually violates the rule of how MXF handling descriptive metadata, and it is not recommended by IRT and myself.

2. Using DMS1 (Descriptive Metadata Scheme-1). As mentioned above, the hard part is how to map your metadata to DMS1. And there is not too much products on the market provide the use the full capability of editing DMS1.

3. Using private descriptive metadata. For example, put the metadata in an XML, register a private descriptive metadata scheme UL and a private key with SMPTE. When adding the XML to the MXF file, creates a static track, and its DMSegment, then links the KLV for your XML to the DMSegment. The problem of this way is that it is only for the internal use within an organization. When the file is given to another organization,, then the metadata becomes useless. 

Personally, I would chose the 3rd way for handling descriptive metadata in MXF files. An improvement I would suggest is to append the XML schema after the XML itself, so that it is easy to know what is in the XML, and also easy to map the XML in to a GUI to allow the user to edit the metadata.