M-AUDIO Pro Tools Recording Studio - Manual (Page 978)

Pro Tools Reference Guide 960
Dithering
Dither can significantly improve audio quality
when reducing the bit depth of digital audio.
When to Use a Dither Plug-in
You should use a dither plug-in in any situation
where you are reducing bit depth, for example,
when mixing down to a 16-bit file with the
Bounce to Disk command, or when sending
your final mix to an external digital device that
records at 16-bit resolution.
A dither plug-in is necessary even when mixing
down to 16-bit from a 16-bit session. Even
though 16-bit sessions use 16-bit files, they are
still processed at higher internal bit depths.
• Pro Tools|HD systems use 24-bit audio input
and output signal paths, and internal 48-bit
mixing and processing
• Pro Tools LE and M-Powered systems use 24-
bit audio input and output signal paths, and
internal 32-bit floating point processing for
mixing and audio processing
For this reason, whether you are working with a
24-bit session or a 16-bit session, the following
are recommended:
• When mixing down to a 16-bit destination,
use a dither plug-in on the main output.
• When bus recording a submix to a track in the
same session, do not use a dither plug-in on
the destination track.
• When mixing down to a 24-bit destination,
do not use a dither plug-in on the main
output.
• When mixing down to an analog destination
with any 24-bit capable interface, do not use a
dither plug-in on the main output.
• During normal recording and playback, by-
pass any dither plug-in on the main output.
Bounce to Disk
Bouncing to disk does not apply dither when re-
ducing bit depth. To apply dither when bounc-
ing to disk, you should insert a dither plug-in as
the last processor in the signal path on a Master
Fader assigned to the bounce source audio out-
put path.
Using a dither plug-in on a Master Fader is pref-
erable to an Auxiliary Input because Master
Fader inserts are post-fader. As a post-fader in-
sert, the dither plug-in can process changes in
Master Fader level.
If you do not use a dither plug-in on your
bounce source path, and you choose to convert
to a lower resolution during or after bouncing to
disk, the resulting file will be converted by trun-
cation.
Using Dither on an Output Mix
Pro Tools includes real-time dither plug-ins that
improve 16-, 18-, or 20-bit performance and re-
duce quantization artifacts when reducing the
bit depth of an output mix.
To use a dither plug-in on an output mix:
1 Choose Track > New and create a (stereo) Mas-
ter Fader track.
2 Set the output of the Master Fader to the out-
put or bus path you want to bounce.
3 Assign the outputs of all audio tracks in the
session to the same path you selected in step 2.
The Master Fader now controls the output levels
of all tracks routed to it.
4 On the Master Fader, insert a dither plug-in as
the last processor in the signal chain.
5 In the dither plug-in window, choose an out-
put Bit Resolution and Noise Shaping setting.