EVER heard a fantastic piece of music on the radio, only for the DJ to babble
on afterwards without naming the track? It鈥檚 downright annoying鈥攂ut
there鈥檚 an answer to this problem on the way.
Boffins at the Eindhoven labs of Dutch consumer electronics giant Philips
have a disarmingly simple idea: as the tune is playing, you can dial the number
of a service provider and place your cellphone near the radio (or TV) speaker
for a few seconds. A computer system analyses the music and cross-checks it
against a vast database. Moments later, you should get a text message naming the
tune. It will even give you the option of buying the CD via a standard mobile
e-commerce transaction.
The company got its inspiration from a cryptographic technique called
hashing, which is a way for computers to check that they have safely received a
long message. Hashing works by comparing chunks of data or words in the
transmitted message and then creating short, unique codes that can only be
created by the message. These codes are transmitted with the message. If
different codes are created by performing the same operation on the received
message, it means the transmission has gone wrong, corrupting the data. So the
message must be sent again.
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For the musical version of hashing, Philips intends to create a unique
fingerprint for each tune so it doesn鈥檛 have to store the whole memory-hungry
song. To do this, its technology divides the sound of a song or instrumental
piece into 33 narrow frequency bands and then measures the energy in each band.
With these energy measurements the company can calculate hash codes that are
unique to each tune.
Philips wants to set up a central database of hash codes representing 100,000
commercially available recordings. When a cellphone sends the sound of unknown
music to the database, the database 鈥渉ashes鈥� the incoming sound and compares it
with its stored codes. When it finds a match, the database sends back the text
message, identifying the song. Philips reckons playing just three seconds of a
song will be enough to identify it.
Others are thinking along similar lines to Philips
(快猫短视频, 27 January, p 7).
Earlier this year, Bill Poel, a private inventor in
Chelmsford, Essex, filed a patent for a system that lets mobile phones identify
CDs. Since CD players can already identify each track on a CD by their inaudible
digital codes, Poel鈥檚 idea is to convert those codes into brief audible bleeps
that a modified cellphone can decode to display the title of the track. But this
won鈥檛 help if the song you are seeking is on vinyl.