Motorola m25 Guide de l'utilisateur télécharger pdf (Page 56)

m25 DIGITAL AUDIO PLAYER 56

The m25 supports MP3 and WMA digital audio codecs. The Advanced Audio Coding (AAC) Codec

, most closely

identified with MPEG-4, is not currently supported by the m25.

Firmware

Firmware is the read-only software that is installed on the player. Like software, it can be updated, but unlike software

it can never be deleted from the player.

Gain

Gain is a measurement of the amplitude of all frequency ranges. Gain adjustments boost or reduce frequencies to

provide a more desirable audio output.

ID3 Tag

The ID3 tag is the part of the encoded MP3 or WMA file that contains information about the digital music file such as

song title, artist, album title, encoding bitrate, track time duration, and so on. ID3 tag information is displayed on the

Album/Artist/Track title line on the player’s LCD.

MP3

MP3 is short for Moving Pictures Experts Group Audio Layer 3. MP3 is the most well known compressed digital audio

file format. This format allows for near “CD quality” sound, but at a fraction of the size of normal audio files. MP3

conversion of an audio track from CD-ROM can reduce the file size by approximately a 12:1 ratio with virtually no

perceptible loss in quality. MP3 compression removes the redundant and irrelevant parts of a sound signal that the

human ear doesn't hear. This digital sound encoding and compression process was developed by the Fraunhofer

Institute for Integrated Circuits and Thomson Multimedia.

AAC was developed by the MPEG group that includes Dolby®, Fraunhofer® (FhG), AT&T®, Sony®, and Nokia®—companies that have also

been involved in the development of audio codecs such as MP3 and AC3 (also known as Dolby Digital). The AAC codec in QuickTime® 6

builds upon new, state-of-the art signal processing technology from Dolby Laboratories and brings true variable bit rate (VBR) audio encoding to

QuickTime.

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Motorola m25 Guide de l'utilisateur Page 56