When we stick a CD into ITunes, we see the artist, songs, art work and all other sorts of disc information that pops up on our screens, all because of metadata. Since the digital era reels of film and audio no longer have to be physically labelled with information, which, more than likely will fall off or deteriorate with time. Thus Metadata is basically digital labelling within the file, CD, DVD, which can provide an abundance of information, incorporated in to the object itself. Some producers don’t always take advantage of this data and just put their composer information into an online database, such as Gracenotes (FreeDB) and expect the user to find the information out via the internet, which many ITunes users have probably done using the ‘get info’ button.
From audio to digital image information, details such as resolution and saturation are just the basics of metadata purposes. And at a professional level the more information used, the closer you are to a piece of work reaching a professional standard.
So let’s break down metadata into its categories which make them easier to understand and make use of:
Source metadata – specified from the device you use to create an object (file, CD etc) such as EXIF format; hosting timecode, duration, codec, GPS setting etc.
Added metadata – are specifics added by the editor/creator such as key words and comments.
Derived metadata – uses external sources to pass on information such as language algorithms and calculation of various time codes.
Inferred metadata – information that can be easily recognized by other metadata sources, such as Added metadata. For example, we have the same person in five scenes, the inferred metadata would know it’s the same person, but the added metadata would be a description on that person, IE. John.
Once we know the basics of this data we can manually add further information to assist those viewing/using our files; and this is where standards from amateur to profession are evident.
A specific look into professional use of Metadata is the Dolby Digital transmission bitstream; that delivers programming to the home via digital television. Dolby use metadata to encode the parameters of the program, i.e. Loudness, panning, dynamic range, set by the program creator. This data can then be encoded to fit with the specifics of the consumer, for example, those with surround sound systems. For post production engineers Dialnorm is one of the most important metadata parameters, and encoding the wrong metadata for your dialog can result in an extremely loud or quiet conversion, making both the creator and distributor look bad.
Take a look at Dolby’s Metadata guide, for more professional standard information: