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

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.


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.

5 thoughts on “Broadcast Flag Follow-up

  1. Thanks for really delving into this Chris. It is unique insights like these that I don’t find elsewhere that bring me to your blog everyday.

  2. I still say the most interesting thing about this is that Canadians get screwed by CGMS-A every day on dozens of shows and no on e gives a shit. It happens once in the US and it is front page news!

  3. Chris,

    Can you find out the answer to why Microsoft voluntarily supports the CGMS-A copy prevention method in Windows Media Center?

  4. From the article above….”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.”

    The reason they have supported CGMS-A is because they knew it would be a gateway for official support of various other TV signals, all of which are protected using non-Microsoft technologies.

  5. “Please note that Windows Media Center does not support Broadcast Flag.”

    It’s worth pointing out that this statement is not synonymous with “Windows Media Center ignores the Broadcast Flag.” In fact I think that’s part of Chris’s point. An unsupported feature is simply a behavior that is undefined and/or untested. If a feature is truly unsupported you can’t guarantee what will happen when you attempt to use it.

    Regardless of what Microsoft actually meant by this statement, MCE includes code intended to deal with copy restrictions and other types of rights management. If you look at all the permutations of flags, streams, and whatever else goes into recordings, you’re bound to hit some scenarios that aren’t supported and may inadvertantly execute that copy protection code.

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