Apple Logic Pro X - Manual (Page 859)

Chapter 25 Preferences, project settings, and key commands 859
MP3 preferences
MP3 preferences are only available when Show Advanced Tools is selected in
Advanced preferences.
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Bit Rate (Mono/Stereo) pop-up menus: You can choose bit rates between 32 kbps and 320 kbps,
but the defaults are 80 kbps mono and 160 kbps stereo. These rates offer acceptable quality
and good file compression. If you can afford the increased file size, you should choose 96 kbps
for mono and 192 kbps for stereo streams. These settings will deliver better audio quality. You
can choose even higher rates, but the quality of improvement in bit rates above 96/192 kbps
is minimal.
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Use Variable Bit Rate Encoding (VBR) checkbox: Variable Bit Rate (VBR) encoding compresses
simpler passages more heavily than 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 unselected by default. If you know that the audience for your MP3
files can decode VBR-encoded MP3s, you can select this option.
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Quality pop-up menu: Keep this set to Highest whenever possible. Reducing the quality
accelerates the conversion process, but at the expense of audio quality. This option is only
accessible when the Use Variable Bit Rate Encoding (VBR) checkbox is selected.
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Use Best Encoding checkbox: Like the Quality checkbox, if you deselect this option, you will
gain encoding speed at the price of audio quality. This should always be left selected, unless
conversion time is an issue.
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Filter Frequencies Below 10 Hz checkbox: When selected, frequencies below 10 Hz (which
are usually not reproduced by speakers, and aren’t audible to human ears at any rate) are
removed. This leaves slightly more data bandwidth for the frequencies that humans can
hear, resulting in an improvement in perceived quality. Only deselect this option if you’re
experimenting with subsonic test tones, or exporting MP3s for whales.
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Stereo Mode pop-up menu: Choose between Joint Stereo or Normal Stereo. Depending on the
original file, these settings may or may not offer any audible difference. Experiment with both
settings to determine your preference.