DigiDesign DigiRack, Manual

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DigiRack Plug-ins Guide 28
Voice Usage and Total Latency for
RTAS Plug-ins
With Pro Tools HD, the initial insert of an RTAS
plug-in may cause additional latency, and will
take up two additional voices per channel
(1 voice for input and 1 voice for output) in the
following conditions:
• When inserted on an Auxiliary Input or
Master Fader track
• When inserted on an Instrument track that
does not contain an instrument plug-in
• When inserted after a TDM plug-in on any
kind of track
For example, the initial insert of an RTAS plug-
in on a mono Auxiliary Input track uses two
voices (one channel with two voices), while the
initial insert of that plug-in on a
stereo Auxiliary
Input track uses four voices (two channels with
two voices each).
Subsequent RTAS plug-ins on the same track do
not take up additional voices unless a TDM
plug-in is inserted between other RTAS plug-ins.
Furthermore, one additional voice is used for
each occurrence of any of the following condi-
tions when using voices for RTAS plug-ins on a
track:
• When you use an external side-chain for an
RTAS plug-in on that track
• When you select multiple outputs for that
track (one voice used for each output)
• When you select an AFL/PFL Path output
in the Output tab of the I/O Setup dialog
(one voice used for each channel)
Ordering RTAS and TDM Plug-ins on an
Audio Track
With Pro Tools HD, when RTAS and TDM plug-
ins are combined on an audio track, the order in
which they are inserted has different results:
RTAS Plug-ins Grouped Before TDM Plug-ins No
additional voices will be used, and no process-
ing latency will occur. RTAS plug-ins will be by-
passed when Record Enable or TrackInput mon-
itoring is enabled for that track.
TDM Plug-ins Grouped Before RTAS Plug-ins Each
initial insert of an RTAS plug-in after a TDM
plug-in will cause processing latency, and will
use voices as described in “Voice Usage and To-
tal Latency for RTAS Plug-ins” on page 28. RTAS
plug-ins will stay active while Record Enable or
TrackInput monitoring is enabled for that track.
Ordering Recommendations
When combining RTAS and TDM plug-ins on
an audio track, use one of the following two
strategies based on your recording needs:
• To ensure that RTAS plug-ins stay active when
you record enable a track or use TrackInput
monitoring, group all TDM plug-ins before
RTAS plug-ins.
– or –
• To conserve voices and minimize processing
latency, group all RTAS plug-ins before TDM
plug-ins.
Avoid inserting TDM plug-ins between
RTAS plug-ins on any kind of track—this
causes unnecessary voice usage and may
cause additional latency.
As a rule, always group plug-ins of the same
type together, especially if inserting RTAS
after TDM plug-ins. Otherwise, additional
voices may be unnecessarily used, and un-
necessary latency may result.