User guide

Pro Tools|HD User Guide48
Delay Compensation Engine
The Delay Compensation Engine setting deter-
mines how much DSP resources are dedicated
for Delay Compensation.
To maintain phase coherent time alignment,
Pro Tools adds the exact amount of delay to
each track necessary to make that particular
track’s delay equal to the total system delay. The
System Delay is shown in the Session Setup win-
dow (Setup > Session).
Delay Compensation should be enabled during
mixing and playback for phase coherent time
alignment between track outputs.
When recording, in most cases Delay Compen-
sation can be enabled. However, it is still recom-
mended that you disable Delay Compensation
for certain dubbing workflows (such as when re-
cording to multiple audio tracks in series).
To configure the Delay Compensation Engine:
1 Choose Setup > Playback Engine.
2 From the Delay Compensation Engine pop-up
menu, select a Delay Compensation setting.
3 Click OK.
Delay Compensation Settings
There are three settings in the Playback Engine
dialog for dedicating DSP resources for Delay
Compensation:
None Allocates no DSP resources for Delay Com-
pensation.
Short Allocates minimum DSP resources of De-
lay Compensation for each channel. This is the
most efficient setting for Pro Tools|HD Accel
systems. For sessions with only a few plug-ins
that do not induce too much delay, this setting
should be sufficient.
Long Allocates maximum resources for Delay
Compensation for each mixer channel. For ses-
sions with a lot of plug-ins resulting in a large
amount delay, select this setting.
DAE Playback Buffer Size
The DAE Playback Buffer Size determines the
amount of memory DAE allocates for disk buf-
fers. In addition to levels, the DAE Playback Buf-
fer Size shows values in milliseconds, which in-
dicates the amount of audio buffered when the
system reads from disk.
The optimum DAE Playback Buffer Size for most
disk operations is 1500 msec (Level 2).
• DAE Playback Buffer Size settings lower than
1500 msec (Level 2) may improve playback and
recording initiation speed. However, a lower set-
ting may make it difficult to play or record
tracks reliably with sessions containing a large
number of tracks or a high density of edits, or
with systems that have slower or heavily frag-
mented hard drives.
With Delay Compensation enabled, it is
recommended that you do not use any in-
serts on any Auxiliary Input or Master
Fader tracks you may be using to control the
cue mix volume. Also, you should avoid us-
ing inserts on any record tracks. (Some low
latency inserts may be acceptable depend-
ing on the recording situation.)
For more information on using Delay Com-
pensation, see the Pro Tools Reference
Guide.