Friday, September 17, 2010

HDCP Utterly Broken, Intel Doesn't Care

I've been following this story for days now, and it appears Intel has responded saying that the master key that has been released is the real deal. From Ars:

Intel, unsurprisingly, said that it expected HDCP to remain effective. The spokesman told CNET, "There's a large install base of licensed devices including several hundred licensees that will continue to use it and in any case, were a [circumvention] device to appear that attempts to take advantage of this particular hack there are legal remedies, particularly under the DMCA [Digital Millennium Copyright Act]."

In other words, Intel and the media companies don't care that their encryption systems offer only token protection and consumer inconvenience; all that matters is that the encryption systems are sufficient to meet the DMCA threshold for a content protection system: the threat of legal action, rather than cryptography, is their real tool against unapproved uses of digital content.

My thoughts exactly; by using an encryption scheme they knew was easily breakable and easy to implement, they can still claim they tried to protect copyrights with this technology so the DMCA applies.

They are wrong about being protected though; its only a matter of time before someone programs a little custom microcontroller or FPGA to use the key to make perfect digital copies of any content over HDMI. Then of course, they make all the code and PCB designs available for free. Hobyists and grey market peddlers alike will start making these things, and probably selling them on eBay. In other words, once something like this gets out, legal action won't be enough to stop its proliferation.

Thursday, September 2, 2010

iTunes formats converge on 720p, and why aspect ratio matters

While reading some forums about MP4 authoring, I came to the realization that Apple has finally converged on one video resolution for all of its devices. This is pretty nice, since there will be no more iTunes video downloads that are two files, one for your iPods/iPhones, and one for your AppleTV; now, the ENTIRE video playing mobile line (iPod touches, iPhones, iPad) plus AppleTV support H264 MP4 at 720p.

Now, the iPhone, iPod touch, and iPad all don't ACTUALLY have this many pixels on the screen, so your video format is always downscaled for viewing on these devices, but the format convergence is a huge enough of a benefit to offset this effect.

But the pixel mismatch is pretty huge too. In fact, the iPhone's/iPod's 960x640 display is two thrids the pixels of 720p, and after you scale a true 720p video to fit on the screen and take the aspect ratio mismatch (black bars) into account, your screen shows "540p" video, for only 56.25% of the pixels of 720p. The iPad isn't much better; it has about 85% of the pixels of 720p, but a 720p video on the screen shows up as "576p" with 64% of the pixels of 720p.

The point here is that aspect ratio really matters when you talk about video formats and video playback devices. Although Apple has converged on a format, they haven't converged on an aspect ratio, and it really makes a difference to your viewing experience. Now, whether or not they CAN do so is a hard question, but it makes for interesting food for thought. With several different film formats, SDTV, HDTV, DVD, recording equipment, etc. all having slightly different resolutions and aspect ratios, and with all the converting that goes on in the media authoring process, its still a big open question. For my two cents, the HDTV standards of 720 or 1080 lines in a 16:9 aspect ratio seem to be driving the digital video revolution we're seeing. Like Steve said the other day, people want to see TV shows, and they want them cheaply. Clearly ABC and FOX are on board for this 99c rental thing, and all of their shows are authored in 16:9 because HDTV standards are 16:9, and so this seems to be a reasonable aspect ratio to pick for the latest and greatest hardware platform. As another example, the majority of Netflix use I hear about is for watching TV shows, which are all 16:9. This aspect ratio also seems to kind of be smack dab in the middle of common formats. Its the least "wide" of the formats we consider widescreen, so its still okay for 4:3 SDTV content, and "anamorphic widescreen" formats don't have TOO much screen real estate wasted.

The problem with this reasoning is that its a tradeoff. Any aspect ratio a company picks for its hardware is a tradeoff between watching different types of content, and its really a sorry situation. What's truly necessary is for the film and TV and camera people to all get together on an aspect ratio; here's hoping that happens with 16:9, driven by the current HDTV zeitgeist.