10.6

Table Of Contents
878Logic Pro User Guide
Encoding pop-up menu: Choose Advanced Audio Codec (AAC) or Apple Lossless to set
the encoding for your .m4a (commonly referred to as MP4) file. While both encoding
algorithms provide high-quality audio, the AAC format uses a higher compression ratio,
resulting in smaller file sizes.
Choosing the M4A:AAC option in the Destination area disables PCM > Surround. Split
Stereo is still available.
If the selected sample rate is higher than 48kHz, a copy of the bounced PCM file is
created (with an automatic sample rate conversion to 48kHz) before encoding. This
conversion takes place because the M4A format does not support sampling rates higher
than 48kHz.
Bit Rate pop-up menu: Choose a rate between 16kbps and 320kbps.
Note: This parameter is only available when the AAC codec is chosen.
“Encode with variable bit rate (VBR)” checkbox: Variable Bit Rate encoding compresses
simpler passages more heavily than passages that are (more) harmonically rich,
generally resulting in better quality files.
Because not all media players can accurately decode VBR-encoded files, this option is
off by default. If you know that your target listeners can decode VBR-encoded files, you
can turn this option on.
Add to Music” checkbox: Check this box if you want to add the .m4a file to your Music
library.
Note: If your Mac is running macOS Mojave or earlier, an “Add to iTunes” checkbox
replaces the “Add to Music” checkbox.
About dithering algorithms in Logic Pro
Logic Pro includes the professional POWr (Psychoacoustically Optimized Wordlength
Reduction) and UV22HR dither algorithms, designed to convert 24-bit recordings to 16-bit
files (as required for CDburning, for example). Dithering can be used when:
Burning audio files to a CD
Bouncing audio files to disk
Exporting AAF files (See Export a Logic Pro project as an AAF file.)
The following dithering options are available in the Bounce dialog:
None: No dithering is applied.
POWr #1 (Dithering): A special dithering curve is used to minimize quantization noise.
POWr #2 (Noise Shaping): Additional noise shaping is used over a wide frequency
range, which can extend the dynamic range of the bounce file by 5–10dB.
POWr #3 (Noise Shaping): Additional, optimized noise shaping is used, which can
extend the dynamic range by 20dB within the 2–4kHz range (the range in which human
hearing is most sensitive).
Note: Noise Shaping minimizes the side effects caused by bit reduction
(downsampling), by moving the quantization noise spectrum to the frequency range
above 10kHz (the least sensitive part of the range of human hearing). This process is
technically known as spectral displacement.
UV22HR: Allows for the best possible sound resolution when bouncing 24-bit
recordings into 16-bit files.