i Tunes store, the profit margins on delivering rich media content are enough to
induce sweaty palms in any chief executive.
AT&T has been rolling out their cable
TV competitor, U-Verse, which delivers
media content over the same high-capacity
lines that also carry Internet data. If they
smell money to be made offering exclusive
media, attracting partnerships with record
labels and studios could be reason to
embrace the kind of content filters these
companies are so desperately seeking.
But what about safe harbor and liability?
Pundits are still scratching their heads.
Talking about content filtering is one
thing—actually doing it is quite another.
An effective filter needs to identify audio or
video data that could be contained in a
wide variety of formats. Data can be compressed, transformed, and distorted in a
wide variety of ways. It is not difficult for
a human to recognize that a camcorder
recording of a theatrical screening is the
same content as the DVD rip. It is much
more difficult for a computer to do so.
Furthermore, an effective filter needs to
make its distinctions quickly, using the
smallest samples of data feasible, with the
least computation demands possible, or
else it will exact a costly performance
penalty on the whole network.
Back when the original Napster was
spooking the music industry, record labels
looked for infringing songs with a very
primitive approach: by filename. Wily file
sharers simply changed the names of files
to misidentify them. Today’s filters are a lot
more sophisticated. But even after years
and millions of dollars of development,
they remain imperfect.
Acoustic fingerprinting like that developed by GraceNote is designed to calculate
a unique “score” for a particular audio
track based on its perceptual qualities.
Compression techniques like MP3 and
AAC use psychoacoustic models to determine which audio bits can be “thrown
away” while still maintaining a similar perception experience for the listener.
Likewise, acoustic fingerprints have to go
beyond the exact set of bits that make up a
particular file, because every compressor
will produce a slightly different file.
The technology behind acoustic fingerprinting is now quite effective. But to identify any individual track, you need a
fingerprint to compare it to, and that
means a database—a huge database. For
the database to be useful, it needs to contain millions of acoustic fingerprints calculated from authorized recordings.
Such a database can never be truly comprehensive—a live recording of a U2 concert may not produce the same acoustic
fingerprint as the tracks from their CD, for
example. Plus, GraceNote is not alone in
licensing fingerprinting services, meaning
that multiple vendors with different algorithms compete in the market. It is not
realistic to expect every record label to pro-