Making the Most of Metadata

Roger Franklin

LONDON —The TV landscape has changed dramatically in recent years, with consumers growing accustomed to receiving content they want when and where they want it. With this evolution is increased pressure on video providers to know what the customer wants and to provide recommendations and compelling value added services. Providers are tapping into metadata to increase service value and generate new revenue and business models.

Metadata has been present in video streams since the middle of the 1970s. It is in the changing environment of consumer-driven content consumption that metadata is the way to enhance the viewing experience.


With the SCTE-35 standard becoming a requirement, metadata must be handled in a very specific way. There is some confusion as to what adhering to the standard actually involves.

The SCTE-35 standard provides more flexibility than previous methods, making it possible to fully describe a segment within a program. SCTE-35 messages not only define the start and stop points of a segment, but also the duration, and the content within the segment. This flexibility makes it easier to provide personalized content.


Two primary pieces of metadata are required within the video stream: the first identifies where in the stream a segment starts and ends; the second identifies what content is present in that segment.

In order to set those parameters, the video provider must determine what constitutes a segment for them; e.g. the main program is often one segment, with other segments for national and local advertising spots.

SCTE-35 can be used to define more specific segments than that. Individual scenes can be defined, enabling the possibility of scene substitution based on the age and preference of the viewer.

The rules for content replacement are defined outside of the video stream and should follow the Event Signalling and Management (ESAM) and Event Scheduling and Notification Interface (ESNI) standards.


SCTE-35 splice messages indicate where to replace content in a video stream. Splice points must be identified at the beginning and end of the content segment. Every splice point should begins with and encoder-created IDR frame and the encoder should insert the SCTE-35 splice message. The splice commands are contained within a splice information section SCTE-35 message. 

Because duration is present, while it is good practice to supply both the start and stop points, it is only a requirement to provide one.

SCTE-35 messages are used to define what content is in each segment. Splice descriptions identifying the content in each segment can be added to a splice information section message. The SCTE-35 standard predefines three types of descriptions: the Avail descriptor is added to the splice insert command, and this descriptor functions like a cue tone. It is interpreted by the receiving equipment as a splice point for substituting local advertising into the program stream.

The DTMF descriptor instructs a receiver to initiate the specified DTMF tone. The result of this descriptor is the same as the Avail, but it accomplishes this by signaling older splicing equipment that still require the audible DTMF tones.

The segmentation descriptor is used to define the content of a program segment. This descriptor has fields that are used to turn web distribution on or off, or mark whether a segment should or should not be blacked out.

According to the specification, the segmentation descriptor is added to a time signal command or other splice commands, and is used to identify the content of a new upcoming segment. The segmentation descriptor message should be delivered at least four seconds before the beginning of the segment, but is often delivered eight to 12 seconds before the segment.


With the pace of change in the video distribution industry, it is clear the future for content distributors is in the value added to the distributed content. It is a challenge to implement new standards quickly, especially when you need to leverage older equipment and systems that are not fully compliant. However, the companies that plan today to manage content smartly will reap the rewards, delivering compelling content to viewers, and generating new revenue streams.