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Ext2: MP3 Under Linux

Feb 14, 2000, 20:03 (0 Talkback[s])
(Other stories by Bjoern Ganslandt)

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"The audio compression standard Mp3 (MPEG 1 Layer 3) has become very popular recently. Mp3 is a "lossy" compression, that tries to reduce the audio data to the information which is actually heard by a human. The Mp3 encoder uses a psychoacoustic model to decide whether information is relevant or not. A strong signal, for example, will "mask" some of the following (weaker) signals. Because of this, it is complicated to technically measure the quality of Mp3 compressed music. The only way to "measure" the quality of an Mp3 encoder is to use human testers, which tend to be very subjective. So much on the theory, now lets have a look on what you need to encode/play Mp3's on your Linux box."

"In case you want to convert your old audio CDs into Mp3, you will need a CD-ripper. A CD-ripper gets the digital data from the CD without loss. If you would use a standard wave recorder, the data on the CD would be converted into a analog signal and back into a digital signal by your sound card, before it would reach the recorder. This causes quality loss, but if your cdrom doesn't support ripping, it is your only choice. One of the most used CD-ripper is probably CDParanoia , it exports the audio data as wave or aiff file which can be used by an encoder."

"The next thing you need is a Mp3 encoder to compress your sound files. There are several Mp3 encoders for Linux, most of them are based on the dist10 ISO demonstration code. One of those encoders is Bladeenc. It's quality is limited by the ISO psychoacoustic model and it doesn't support variable bit rates. Variable bit rate means that the encoder can adjust the bit rate to the complexity of the signal. There's another program named LAME, which stands for LAME Ain't an Mp3 Encoder. As the name indicates LAME is not an Mp3 encoder, but a GPLed Patch against the dist10 code. This way LAME doesn't violate any Copyrights of the FhG."

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