Apple Logic Pro 7 - Manual (Page 376)

376 Chapter 9 Audio Window
Optimizing Synchronization over long time-spans
Different computers, different synchronization sources (Internal or SMPTE code),
different tape machines and—in theory—even different samplers or hard disk
recording systems, will exhibit slight variations in clock speed. Changing just one
component can lead to a loss of synchronization between recorded audio material and
MIDI. This is particularly applicable to long Audio Regions.
This is another situation where the Strip Silence function can help, by creating several
shorter Audio Regions, with more trigger points between the audio and MIDI events.
Further Options
Setting the Sample Rate
Logic performs a real time, native sample rate conversion. Any sample rate available in
Logic (via Audio > Sample Rate) can be used for the conversion—even if your audio
hardware does not support the selected sample rate.
The native software sample rate conversion facility matches the sample rate of any
audio hardware, thereby allowing the playback of projects on virtually any audio
system—even if the hardware is—in sample rate terms—not compatible. Nothing is
lost in the process. Any internal processing and bouncing is always performed at the
original sample rate, and at the highest quality, even in cases where the hardware does
not support a particular sample rate. This facility allows you to work on projects
originally created on high-end audio systems, with smaller setups.
Example:
A song was created with an audio hardware/setup at 96 kHz. Moving this project to a
laptop, or setup that does not support the original project’s sample rate, will commonly
result in the wrong playback speed. The native realtime sample rate conversion facility
will counteract this effect, allowing correct playback of the project on the laptop, at any
sample rate.
High sample rates not only eat drive space, but also result in more CPU load, because
everything has to be handled in half the time.
Varipitch/Varispeed synchronization
The real time sample rate conversion facility allows Logic’s audio engine to follow an
external MTC signal (“MTC continuous”), while maintaining the correct playback pitch
and speed. This even works when recording in MTC-slave mode.
Specific Hardware Options
The Audio window menus provide various items related to specific audio hardware,
such as Digidesign systems. Check them out.