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mp3 - data compression




Assignment

CD-changers for 6 - 10 CDs in the boot or above the glove compartment are a thing of the past. Using the compression format mp3 however, 10 - 14 CDs can be copied to only one disc. On condition of course, that the CD-player in the car radio can handle this format. Indeed, this is only the beginning. Give some thought to DVDs or to the, already available with their own hard-disc, which can save 17.000 songs and more, at the moment however, they still cost about as much as a basic navigation system.

Function

For this we have to thank the Fraunhofer-society, they were the ones who invented the mp3 compression format. The fact that compression leads to a higher effectivity, could already be seen by the introduction of a compression stroke in the combustion engine through Nikolaus August Otto. This kind of compression is called a lossy compression, because thereby information is lost. Just how much is lost, can be seen in the compression rate. Indeed, even experts are often unable, even with a relatively high compression of 128 kbit/s, to hear the difference between the original and the copy. For use in the car it's definitely sufficient.

The only real disadvantage of mp3, is the compressing and decompressing of data. The compressing can (almost) be avoided, if one downloads the music (legally please!) from the internet. That solves any problem concerning the compression rate. However, a certain amount of computer capability in the audio/video system is absolutely necessary. If the car radio with CD-player carries the description "MP3", then it can, (as a rule) handle data-CDs in mp3-format. Using a computer one "burns" the data onto these CDs, saving oneself the expense of buying a CD-changer.

It becomes even more interesting with the - indeed, still very expensive - car radios which have their own hard-disc. In this case, one can, using the USB-interface which all computers have nowadays, copy the music-data directly to the HD of the car radio. In addition, data and information about the individual songs is also available from the internet, which is then shown on the radio's display. In fact, nearly too much information, the driver can't help but be distracted. For those who also want to listen to music outside of the car, he/she goes out and buys a mobile mp3-player. There are models which have only a small amount of memory and are quite reasonable in price, and with a suitable compression rate, play more music than a normal CD does. In this case the data are not saved to a HD, but to a memory chip. Today (2005) expensive devices - indeed with their own HD - can have a capacity of up to 60 GB. This is enough to carry a complete music collection, and anyone can charge them. Apart from music they are also suitable for transporting any form of data.

The performance index of MP3-car radios has increased, the prices however, only moderately. By spending more money, one only gets very little more performance, indeed the optical adaptability can be improved by being able to choose the display colours to fit in with the dashboard surroundings. One can connect almost any additional device, and even digital reception becomes possible. By adding a tuner and an equalizer, the upgrade to an audio-system is possible. Radios with a DVD-player even make it possible to watch movies in the car. For this feature however, one needs, at least one monitor, which is either integrated in the device or pops up on demand, there are also devices which can be mounted almost anywhere in the vehicle. This type of entertainment is of course, not intended for the driver. For this reason, it is recommended that they are only used with earphones or headsets. Indeed, those who believe that interference free TV reception while travelling is possible, will have to be patient, at the moment, this is just not on. 02/11

First mp3-record . . .


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