Introduction; What Is Replay; What Is Mp3; Encoder - inout RePlay 01 User Manual

Replay User Manual v.
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Introduction

1.1 What is Replay?

Replay is a sophisticated audio device with a solid state memory, designed to effectively
manage audio files of every kind, sequences of musical items, timed introduction of spots
and commercials, inside shops, public areas and the Public Address system in general.

1.2 What is Mp3?

Mp3 is an acronym for Mpeg-1 layer 3. This is an audio compression standard which
eliminates sounds which the human ear cannot hear via a psycho-acoustic algorithm. The
purpose of this compression is to reduce the space taken up by an audio file while still
ensuring excellent quality. The greater the compression, the less the audio quality. The
right compromise, which guarantees a quality comparable to that of a Compact Disc, is
128 Kbps (thousands of bits per second) which represents the most widely used manner,
and reduces the size of an uncompressed file by 10 times.

1.3 Encoder

Software which compresses a CD audio or wave file in MP3. There are many programmes
of this kind, and it is virtually impossible to say which is the best.

1.4 Decoder

Software which decompresses an MP3 audio file in order to send it to a digital-analog
converter and reconstruct the original audio signal.

1.5 Player

Hardware and software system able to read MP3 audio files. Replay is able to carry out
this function.

1.6 Wave

High quality audio format (extension .wav), compatible with the tracks of normal music
CD's. If one uses a wave file in format 44.1 KHz/sec. at 16 bit in stereo, one will get
exactly the same quality as a music CD, but the size of the file is about 10Mb per minute.

1.7 Audio compression in various formats.

The following graphic shows the space taken up by an uncompressed audio file of about 5
minutes (.wav) and compressed in MP3 at 128Kbps (MP3).
Wave 51.1 MB
MP3 4.6 MB
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