Thursday, December 7, 2006


Recently I've been looking into TV ratings and parental control features for TVs and digital set top boxes. Not because, I want to censor what my kids watch - they are too young to be interested in anything worth censoring at this point - but for work reasons.

When watching TV you've probably noticed at the beginning of the show (and sometimes coming back from a commercial) an icon that provides some sort of 'rating' indication. It looks a little like this 14+ or this TV14 depending if you are in Canada or the USA (other countries may have something similar - I'm not sure). Since 2001, all TVs with a diagonal screen size of 13 inches or greater must be able to set rating limits based on these rating indications and if set, block the content from view until a PIN is entered. All this functionality is based on the v-chip technology

The Rating Systems
In North America there are four rating systems in effect that can be used to block TV content:

  • The MPAA system we are all familiar with from movies (G, PG, PG-13, R, NC-17, Not Rated)
  • The US TV system (None, TV-Y, TV-Y7, TV-G, TV-PG, TV-14, TV-MA) which has additional letter descriptions (FV - Fantasy Violence, V -Violence, S - Sexual Situations, L - Adult Language, D - Sexually Suggestive Dialogue)
  • The English Canadian TV System (E(xempt), C, C8+, G, PG, 14+, 18+)
  • The French Canadian TV System (E, G, 8ans+, 13ans+, 16ans+, 18ans+)
In Canada, a lot of programming is exempt from these ratings because of freedom of speech concerns including news programs, sports, documentaries, talk shows, informational programming, and music videos (!)

How Does the TV Know the Rating
The TV can't 'read' the screen to see the rating of the current program, instead it reads data from the VBI (a vertical blanking interval) where other information like closed captioning data is stored. If you have a really old TV where there is a knob to adjust the vertical sync of the picture you can turn it and see a black band instead of video. This black band actually contains data including the rating information for the program. Maybe a later post will explain VBI and all the information that can be pulled out of it.

Why Do I Care About This?
Well, I find it fascinating that the Cable TV industry puts such a high importance on parental controls yet often leaves the implementation of it as an afterthought. At work we often talk about 'little Timmy' seeing naughty video' when discussing potential optimizations to tune times. Nothing we do to improve the performance is acceptable if little Timmy could see or hear a flash of restricted content. But the enforcement and setting of parental controls in OCAP was omitted from the first version (added later as ECR778).

We support more advanced parental control features than just rating in our software as do most electronic program guide providers (block by channel, by title, by time of day as well as by rating) - yet currently there is no way to harmonize parental control settings set for VBI/V-CHIP ratings on your TV and the parental controls set via the guide UI you might be using for digital TV.

I'm thinking about ways to harmonize the two now so 'little Timmy' can't bypass the parental controls set in one system by starting to use the other system.

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