User`s guide

379
appendix a
DSP-Induced Delays in Mixing
In all digital systems, signal processing in-
curs signal delays of varying amounts.
These delays can vary from as short as sev-
eral microseconds to as long as several mil-
liseconds, depending on the type of pro-
cessing being performed.
Delay Factors
In Pro Tools, delay is incurred when you
perform the following processes:
Bouncing Tracks
Bus-based bounces When you bus a track
to another track and record the result, the
following delays are incurred:
Bounce to Disk The File > Bounce To Disk
command causes no delay on a TDM-
equipped system since delay compensation
for the bounce function is built in. This
form of bouncing may be more desirable
than bus-based bouncing.
Use of Inserts & Sends
The following delays are incurred when
you add an Insert or Send to a track:
• Insert: 2 samples
• Post-fader Send: 6 samples
• Pre-fader Send: 3 samples
Use of Hardware Inserts
When an Audio Interface peripheral is used
on an Insert, there are two sources of delay:
the samples incurred in using an Insert,
and a delay introduced by going through
the D/A and A/D converter pair (for analog
devices) or digital I/O connection (for digi-
tal devices) on the Audio Interface.
On the 888/24 I/O, the Digital I/O delay in-
curred when using AES/EBU or S/PDIF is
identical.
Bus-based bounce delays for each Pro Tools system
Pro Tools Hardware Delay
Pro Tools 24 8 samples
Pro Tools 24 MIX 10 samples
Audio Interface Delay Characteristics
Interface A/D/A delay Digital I/O
888/24 I/O 81 samples 17 samples
882/20 I/O 75 samples 17 samples
1622 I/O 75 samples 17 samples