Apple Logic Express 7 - Manual (Page 481)

Chapter 20 Song Settings and Preferences 481
Audio Preferences: MP3
Bit Rate (Mono/Stereo)
The bit rates are selectable between 8 kbps and 320 kbps, but default to 80 kbps mono,
and 160 kbps stereo. These rates offer acceptable quality and good file compression. If
you can afford the extra file size, we recommend selecting 96 kbps for mono and
192 kbps for stereo streams for better audio quality. You can, of course, choose even
higher rates, but the quality improvement in bit rates above 96/192 kbps is minimal.
Use Variable Bit Rate Encoding (VBR)
Variable Bit Rate encoding compresses simpler passages more heavily than more
harmonically rich passages, generally resulting in better quality MP3s. Unfortunately,
not all MP3 players can accurately decode VBR-encoded MP3s, which is why this option
is off by default. If you determine that the listener/s of your MP3 can decode VBR-
encoded MP3s, you can switch this option on.
Quality
Keep this set to Highest whenever possible. Reducing the quality will speed up the
conversion process, but at the expense of audio quality.
Use Best Encoding
Again, like the Quality parameter, if you uncheck this option, you will gain encoding
speed at the price of audio quality. This should always be kept on unless conversion
time is an issue.
Filter Frequencies Below 10 Hz
When this option is checked, frequencies below 10 Hz (which are usually not
reproduced by speakers, and are not audible to human ears at any rate) will be
removed, leaving slightly more data bandwidth for the frequencies which we can hear,
resulting in an improvement in perceived quality. Only uncheck this if you’re
experimenting with subsonic test tones, or exporting MP3s for whales…
Stereo Mode
You can select joint stereo or normal stereo mode. Depending on the original file, these
settings may (or may not) offer any audible difference. Experiment with both settings
to determine your preference.
Audio Preferences: Reset
Send Reset Messages to Audio Instruments:
Reset messages of the specified type (Control 64 off (Sustain), Control 1 (Modulation) to
zero and Pitch Bend to center position) are sent to all active Audio Instrument channels
for each of the checkboxes. This may be useful if you are encountering hung notes, or
are finding that controller settings are incorrect when in Cycle mode or when returning
to the beginning of a section or the Song start point.