This is an extremely popular lossy sound compression algorithm. Amadeus Pro reads Mp3 (and also Mp2) files through the tool mpg123 (see Section 15 below).
Saving Mp3 files is achieved through the tool lame.
(See also Section 15 below.) It supports a variety of settings (the
meaning of the most important one, the bitrate, was explained above).
In order to achieve a given file size, it is recommended to use the
ABR (Average Bit Rate -– simple parts of the sound will be
compressed more than complex parts, achieving a better overall
quality) setting, rather than CBR (Constant Bit Rate -– all
parts of the sound have the same compression rate) in order to achieve
maximum quality, but note that some Mp3 players may not support ABR
files. The VBR (Variable Bit Rate) setting is more flexible
and allows you to specify a target quality rather than a target file
size. This usually results in better sounding files, but you have less
control over the resulting file size (complex
sounds will
produce larger files than simple
sounds for a given quality).
Note also that as with ABR files, not every Mp3 player supports VBR
files. The screenshot next to this paragraph shows a popular setting
that represents a good trade-off between file size and sound quality.
Note that the use of id3v2.4 tags is discouraged since their support
is broken in iTunes (this is true as of iTunes 7).
The Sample rate setting allows you to resample the sound before encoding. In most cases, the Automatic setting will yield best results. For example, when encoding a 44:1kHz AIFF file at 32kbps, lame will resample it to 16kHz. This will in general yield better result since less bandwidth is wasted on highfrequencies and so the lower frequencies can be described more accurately. By changing this setting to Original, this behaviour can be suppressed.
When a multitrack document is saved as an Mp3 file, Amadeus Pro will downmix it to a mono or stereo file, whichever is more suitable. Metadata (including artwork) is preserved in Mp3 files, provided that you choose to create an id3v2 tag.
The remaining settings are mainly for expert usage. If you do not know what they mean, then you will probably not need them.
