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868 Chapter 36 Working With Plug-in Latencies
With plug-in delay compensation set to All, Logic Express shifts the bass track forward
by 10 ms, thus synchronizing the bass and drum tracks. Logic Express will then delay
both streams routed to the output channel by 30 ms, aligning them with the guitar
tracks. The aux channel that the vocals are streamed to is also delayed by 15 ms,
aligning it with the drum and guitar streams (in other words, the 15 ms delay is
increased to 30 ms). The precise calculations required for each stream are handled
automatically.
As you can see in the table, all output is effectively delayed by 30 milliseconds—to
match the largest amount of compensation required (by the effects in aux channel 1,
which the guitar tracks are routed to). This has the effect of perfectly aligning all tracks
routed to the output, and circumventing any delays introduced by plug-ins, regardless
of where they are used in the signal path.
Plug-in Delay Compensation Limitations
Plug-in delay compensation works seamlessly during playback and mixing. The delay
that is introduced—to compensate for latency-inducing plug-ins in output and
auxiliary channels—can be applied to non-delayed streams, before they are played
back. Instrument and audio tracks (that contain latency-inducing plug-ins) can also be
shifted forward in time, before playback starts.
There are, however, some limitations if you use plug-in delay compensation with live
tracks. Shifting pre-recorded instrument and audio tracks forward in time is possible
when the audio is streaming live. So, recording while plug-in delay compensation is set
to instruments and tracks will work fine—as long as you do not try to record through
latency-inducing plug-ins: A live track can not be shifted forward in time (as
Logic Express can’t position live audio before it happens!).
Important: Delaying a live stream, in order to synchronize it with other delayed audio
channels is not possible.
This may lead to problems if you decide to make further recordings after setting plug-
in delay compensation to All, and inserting latency-inducing plug-ins in auxes and
outputs. If Logic Express needs to delay streams to compensate for plug-in latencies,
you will be listening to delayed audio streams while recording. As such, your recording
will be late by the number of samples that the audio streams were delayed by.
Track Uncompensated Compensated
Bass (effect directly inserted in
audio channel)
10 ms delay 10 ms → (audio channel) then ← 30 ms
(output channel)
Guitars (routed to aux 1) 30 ms delay Not changed.
Drums (direct to output) No delay 30 ms ← (output channel)
Vocal (routed to aux 2) 15 ms delay 15 milliseconds ← (aux channel 2)