User`s guide

Chapter 22: Mixdown and Mastering 321
Conversion Quality
The Conversion Quality option sets the
quality of sample rate conversion used to
create the converted file. The higher the
quality of sample rate conversion, the
longer it takes to convert the file after the
bounce has taken place. There are five pos-
sible settings, ranging from Low to Tweak-
head. For most applications, the Better set-
ting yields satisfactory results.
Because the Best and Tweak-head settings
take significantly longer than the others,
use them only in cases where the highest fi-
delity is essential and you have a consider-
able amount of time to devote to this pro-
cess.
Using Dither on an Output
Mix
Pro Tools includes a real-time Dither Plug-
In that improves 16-, 18-, or 20-bit perfor-
mance and reduces quantization noise
when mixing or fading low-level signals.
The Dither Plug-In has no user-selectable
parameters other than Bit Resolution and
Noise Shaping controls.
☞ For more information about the Dither plug-
In, refer to the DigiRack Plug-Ins Guide.
To use the Dither Plug-In on a main stereo
output mix:
1 Choose File > New Track and choose Mas-
ter Fader (stereo) from the pop-up menu.
2 Set the output of the Master Fader to out-
puts 1-2.
3 Set the outputs of all audio tracks in the
session to outputs 1-2. The Master Fader
now controls the output levels of all tracks
routed to it.
4 On the Master Fader, click an Insert but-
ton and choose the Digidesign Dither Plug-
In.
5 In the Dither Plug-In window, choose an
output Bit Resolution and Noise Shaping
setting.
When you use the Bounce to Disk com-
mand, the output will be processed by the
Dither Plug-In.
When to Use the Dither Plug-In
You should use the Dither Plug-In when
mastering to a 16-bit file with the Bounce
To Disk command, or when mastering to
an external device that records at 16-bit.
This is even necessary when using 16-bit
sessions.
Generally, dithering is necessary when re-
ducing the bit depth for digital audio.
Even though 16-bit sessions use 16-bit files,
they are still being processed internally at a
higher bit rate:
• 24-bit for Pro Tool TDM systems
• 32-bit floating for Pro Tools LE systems
For this reason, whether you are using a
16-bit session or a 24-bit session, it is rec-
ommended that you use the Dither Plug-In
when mastering to 16-bits.
When mastering to 24-bits, it is not neces-
sary to use the Dither Plug-In.