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Chris Lanier's Blog

Broadcast Flag Follow-up

I’ve been attempting to learn about the Broadcast Flag over the past few days, and instead of focusing on what it can/can’t do I decided to look at a few other things.

First of all, I want to say that I believe the issue early this month with NBC was a total fluke.  I think a lot of people are getting bent out of shape considering this has been and continues to be a onetime bug not reproducible by anyone at Microsoft, NBC, EFF, etc.  This is compounded with the lack of understanding between different technologies, mainly Copy Generation Management System - Analog (CGMS-A) and the Broadcast Flag.  The Broadcast Flag only applies to Over the Air (ATSC) broadcasts.  It doesn’t and can’t apply to NTSC, CableCARD, etc.  It is understandable that people are upset when something like this happens (especially with the longstanding CGMS-A issues, and CableCARD issues that mostly appear to be software conflicts), but everything needs to be kept in check.

With all of that said, this whole situation doesn’t match up.  On Microsoft’s side first, they said "Microsoft included technologies in Windows based on rules set forth by the (Federal Communications Commission).”  CNET published the story under the title “Microsoft confirms Windows adheres to broadcast flag” despite the fact nothing they published from Microsoft said “Broadcast Flag.”  It is also worth noting that the FCC doesn’t have any rules on the Broadcast Flag.  Ten days later CNET published a follow-up story refuting parts of their previous story quoting Microsoft as saying “Please note that Windows Media Center does not support Broadcast Flag.” 

Cut to NBC’s side of things, CNET reported that NBC “made an inadvertent mistake” and “incorrectly flagged” the shows in question and they later reported that “It was a CGMS-A flag, not a broadcast flag.”

Where does this leave us?  With a seemingly rare occurrence that can’t be reproduced.  Microsoft says the Broadcast Flag isn’t supported, NBC says they didn’t put the Broadcast Flag on and instead they magically enabled CGMS-A(nalog) on a pure digital ATSC broadcast.  These two bits of information are where things actually get interesting.

NBC first, they are saying they enabled CGMS-A, an analog (NTSC) copy protection technology on a non-analog (ATSC) broadcast.   In NTSC, the CGMS-A bits are broadcast in Vertical Blanking Interval (VBI) which also carries closed captions, V-chip data, and other digital data.  However, best I can find there is no standard for CGMS-A in ATSC broadcasts.  There is a VBI extension for ATSC, but based on the specs it doesn’t support CGMS-A.  Can CGMS-A even be put on ATSC?  Based on what I’ve seen the answer would be no.  If this is the case, it leaves NBC with no idea what really happened on the broadcast end.  If it was somehow CGMS-A on ATSC it would also seem to be a onetime occurrence that has ever been reported before.

On Microsoft’s side, the question is does Windows support the Broadcast Flag?  Microsoft says “Windows Media Center does not support Broadcast Flag,” but there is more to the story then that.  Who knows what the software truly supports, but Microsoft has developed for the Broadcast Flag in the past.  Most notability while developing for Vista which would be prior to the time it was officially stuck down.

Microsoft’s position on the Broadcast Flag is simple and is even semi-outlined in a 2003 document.  Basically it boils down to we will support the Broadcast Flag if it is created with us in mind.  This is exactly how I would expect Microsoft to deal with it in a world of digital video on the Internet and Microsoft wanting to push their Windows Media technologies.  It is no secret, Microsoft supported CGMS-A in Windows Media Center way back in 2002 and now they are the only PC-based platform with CableCARD and pending DIRECTV support.  It is a game that Microsoft knows how to play, and it pays in the end (it also helps grow their digital download aspirations, Microsoft TV division, etc).

Other interesting bits are the ASF specs which reference and start to define how to deal with the “Broadcast Flag” (I’m assuming that’s proper Broadcast Flag and not general flag in a broadcast).  And then there are the PBDA PowerPoint’s from Vista, which show a nice block diagram of 8VSB demodulation (which is ATSC)  with the Broadcast Flag clearly being detected with dealt with.

image

Since Microsoft really never published any of the in-depth specs for PBDA type stuff we don’t know for sure if Windows does “support” it, or rather if Broadcast Flag support is in the live implementation.  I’m not trying to scare anyone or suggest Microsoft wants to kill access to all of your media (they want the opposite), but I think it is important for everyone to understand what can be done.

While I haven’t had the time to do in-depth research on the Broadcast Flag in general, I do see that the issue between NBC and Microsoft from a few weeks ago is appearing to be nothing but a fluke.  I’m interested to see if anything like this (copy protection on ATSC) happens again, but truthfully the situation is looking more like a single rare occurrence to me than an issue with the Broadcast Flag.

Cross Posted from Chris Lanier's Blog at http://msmvps.com/blogs/chrisl/
Published Saturday, May 31, 2008 7:43 PM by Chris - Moderator
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