Back when the first HD disc formats appeared, there were quite a few in the tech industry who declared that no one in their right mind would want to download a high definition movie off of BitTorrent. Well, they were wrong. As the popularity of HD-DVD and Blu-Ray increases in traditional brick-and-mortar stores, so does the number of available torrents on the digital black market.

Before the introduction of high definition, the average DVD rip available on the P2P networks was pretty reasonable in size, ranging from 700MB to a Gigabyte – yes, there were some exceptions, but let’s not dwell on those. An average movie of this size would take about a day to download on a standard broadband connection, and the quality was pretty much on par with that offered by the source DVD, with the exception of surround sound which was simply never there, unless the DVD .iso was made available.

For a lot of people the prospect of having to wait a day for a movie to download so that it can be watched on a computer was pretty disheartening, and was probably also the main reason that many proclaimed that larger file sizes might therefore never work. Well, that argument seems reasonable to most; waiting a day is doable, but any longer than that quickly gets extreme, right?

As it turns out, that is not the case for a lot of high school and college students, who appear to be the main consumer demographic of pirated content. As long as they don’t have to pay for the content that they want, it’s acceptable; regardless of how long it takes to download the content in question. Be it movies, games, music, or software, if they want it, they will get it.

Around the 15th of January, the first high definition movie hit the underground BitTorrent market. The movie: Serenity. The size: a hefty 19.6GB. This occurred barely a day or two after the now (in)famous Muslix64 managed to bypass the DRM protection scheme known as AACS (Advanced Access Content System) on HD-DVD. This very first HD movie was encoded using EnVideo, producing a 1080p .evo file complete with 5.1 Dolby Digital Surround Sound. If you’ve ever watched a 1080p trailer over at www.apple.com/trailers then you know how absolutely gorgeous this stuff can look.

Granted, this first rip of Serenity was quite big; probably due to the fact that it was to serve more as a proof of concept that no matter what the industry tries to do to protect its content, every last bit of data will eventually be ripped to create perfect replica that will be distributed for free. When this very first movie made its way onto the P2P networks, it only served as fuel to the fire for those convinced that no one would want to waste their time and bandwidth downloading close to 20 gigs for a single movie.

In the case in point, the pundits might have been right. For most people, this file was overkill in the sense that most people don’t have a 5.1 setup hooked up to their computer, and probably can’t even display 1080p at full resolution on an average 17” monitor. However, those who thought that these issues might strangle the demand for hi-fidelity video neglected a few critical points.

1080p with Dolby Surround is the crème de la crème, and this will by no means be the standard by which most pirated HD movies will be distributed. Let’s look at it rationally: since most people won’t even be able to take advantage of the full glory of 1080p and surround sound, it would be interest of (almost) everyone if the resolution were to be downscaled and if the sound were only to be offered as stereo. Do this, and the file size will drop dramatically, and the footage will still look better than a lot of the HD offerings that Comcast makes.

The average PC user has a screen resolution of about 1280 by 1024 pixels or less, which is not even remotely close to “True HD,” at 1920 by 1080 pixels. The next step down at 720p is far more feasible for the average pirate, scaling in at a nice 1280 by 720 pixels. Going from 1080p to 720p constitutes a reduction of about 55% in terms of file size. So now, instead of having a file size of 20GB, we’re at about 11GB.

Next, let’s substitute the Dolby Surround for decently encoded stereo. Assuming that if the six audio channels that Dolby Surround uses are each encoded at 128kps, then that would equal 768kps. Since the vast majority of PC users only have a stereo speaker setup or headphones, it would make little sense to offer more than two channels of audio for the average ripped movie. Going from six independent channels to two would decrease the size required for audio storage by about 66%. Now, again, assuming that the audio takes up about 10% of the actual file, we could knock off another gig or two, reducing the file size of the average pirated HD movie to about 9GB.

Obviously there are more factors to consider than merely bitrates of audio and resolution of video. The choice of codecs can also greatly affect the final size of the file. I bet that we’re all pretty much familiar with the most prominent codecs floating around the web these days: DivX, XviD, H.264, MPEG-4, etc. All of these codecs (COder-DECoder) have their own unique way of dealing with the data that they receive in order to produce the desired quality and file size for a given piece of material. By choosing an efficient codec like, say, Theora, it wouldn’t be completely unthinkable to slim the file down by another gig or so.

Now, as proof that I’m not just pulling all of this out of thin air, here are a few torrents that I found of HD movies that are well below 20GB in size:

• Saving Private Ryan in 720p at 7.92GB
• Minority Report in 720p at 6.86GB
• The Fifth Element in 720p at 4.33GB
• The Fifth Element in 1080i at 11.15GB

(Note: For obvious legal reasons, I am not linking to any of these torrents, nor do I encourage the downloading of pirated material…and so on.)

Now, I think that it is perfectly reasonable to assume that a 6.5GB 720p HD movie is well within the realm of patience for the vast majority of those who download movies. Let’s be honest, the 700MB movies were good enough to get the job done, but by no means did those movies ever look great. Considering the major increase in resolution that 720p offers over those old DVD rips, I predict that the number of HD movies seen on underground networks will greatly increase the coming year, and that in the long run, they will come to replace those iffy 700MB rips.