BOOT CAMP 380 (07/06/05)
Downloading video on the
Later this year the BBC
starts trials of a new service for downloading TV programmes over the Internet
using a program called ‘iMP’ or Interactive Media Player. If you are interested
in participating there’s more details and an address for applications at: www.bbc.co.uk/imp/.
The BBC’s iMP program is
based on peer-to-peer (P2P) technology, widely used to download music, movies
and computer software. In fact many BBC television programmes, and those from
scores of other television companies around the world are readily available
online, albeit illegally. The new Doctor Who series famously made it on to the
Internet a week before it was due to be broadcast. Newly released movies are
very popular and UK fans of American TV series are amongst the heaviest users of
P2P, downloading episodes of their favourite shows, weeks or months before they
are screened here.
In this week’s Boot Camp
we’re looking at how P2P video downloading works and you can try it for
yourself, without breaking the law, since there is plenty of perfectly
legitimate material available.
But first it is worth
making a distinction between video ‘streaming’ and downloading. Streaming is the
transmission of ‘live’ video images over the Internet. However, due to bandwidth
limitations -- even on a fast broadband connection -- the quality is relatively poor, resulting
in a small jerky picture. Downloading, as the name implies, involves a large
data file, representing entire TV programme (or movie), transferred over the
Internet and stored on a PC’s hard drive. Once the download is complete it can
be viewed full-screen on the PC’s monitor, though serious users connect the PCs
to their TV (see Top Tip). Unlike streaming both picture and sound quality can
be as good as the original TV broadcast or movie on DVD.
The downside of video
downloading is the volume of data involved. The file for an hour-long TV
programme, for example, can easily exceed one gigabyte and a DVD quality movie
can swallow up almost 5 gigabytes. Needless to say downloading that amount of
data can take a very long time, several hours in fact, so it is only practical
with a broadband connection but the real problem is the strain downloading huge
data files puts on the Internet and the server computers where the files are
This is where P2P comes
in and instead of many users gumming up the works downloading a large file from
a single source P2P shares the burden amongst all of the PCs on which the file,
or parts of the file are stored. Consequently, as more people download the file
it becomes available from more sources, further spreading the load and helping
to speeding up data transfer rates.
One of the first and by
far the most popular P2P download package is BitTorrent, a small program that
gathers in bits of a file download or ‘Torrent’, from the PCs storing the file.
If for any reason a PC supplying data goes offline BitTorrent seamlessly
switches to another source, or sources.
essentially a tool and it has been blamed, a little unfairly, for the increase
in movie piracy. In fact is used by many perfectly respectable companies to
circulate large file downloads, program updates and so on. It is also a valuable
resource for independent video producers, moviemakers and software publishers,
providing a cheap and efficient means of distributing large multimedia
The problem with
BitTorrent, and part of the reason for its dubious and geeky reputation is that
it is completely transparent. In other words there are no restrictions or
limitations on the type of data it is used to download. As far as the BitTorrent
program is concerned it is simply shifting data around the Internet and it could
be anything, from a pirate copy of the latest Star Wars movie to a legitimately
purchased software application.
Unfortunately this also
makes it a little difficult to use, for novices at least. Video and movie
downloads, for example, are available in a bewildering range of file formats,
some familiar, like .avi, MPEG and DivX, but others require additional software
to decode or decompress the data, and in some cases specialist ‘codecs’ and
viewer programs are needed to process and display video images.
The BBC’s decision to
use a proprietary P2P download program should simplify the whole business by
imposing a rigid set of standards. It will also help to limit piracy, control
distribution and manage subscriptions. Downloads will be laced with digital
rights management (DRM) components, which erase or disable the programme after 7
days and prevent copying.
If you would like to try
your hand at downloading video from the Internet, and you have a broadband
connection, the first step is to install BitTorrent program. It’s freeware and
can be found at: www.bittorrent.com/.
You should read the Introduction and FAQ first, particularly if you are
concerned about security issues. Locating material to download can be tricky if
you want to stay on the right side of the law. Torrent Search Engines like
IsoHunt (http://w3.isohunt.com/) will lead
you to vast amounts of pirated material, including files laced with viruses and
other nasties so I suggest a visit to the Legal Torrents web site (www.legaltorrents.com/index.htm)
where you will find a selection of videos, movie and music files, there’s even a
book, which can be legally downloaded.
Next Week -- Google tips and tweaks
Compression/decompression - software utility or add-on used
to process digital data
Highly efficient data compression system used to reduce the
size of large video files to make them easier to transport over the Internet
Moving Pictures Expert Group, Layer 2 -- video compression scheme used by DVD and digital television systems
TIP OF THE WEEK
Connecting a PC to a TV is quite straightforward. Many
laptops and a growing number of desktop machines are equipped with a TV output
socket so all you need is a suitable video cable, (or a wireless TV ‘sender’, if
the PC is located in another room). Otherwise desktop PCs can be fitted with a
TV adaptor card, costing around £25. Most plasma and LCD flat screen TVs have
VGA input sockets, which can be directly connected to a PC or laptop’s monitor
output. The PC’s stereo audio output is connected to the TV’s audio input or fed
through a hi-fi or home entertainment system.