Reference Guide

828
Synchronizing Your Gear
SMPTE/MIDI Time Code Synchronization
Troubleshooting SMPTE/MTC Sync
Playing Digital Audio under SMPTE/MTC Sync
SONAR gives you two choices for controlling audio playback when using time SMPTE/MTC Sync:
Some digital sound cards (such as the Frontier Design Wavecenter or the Antex Studio Card) have
external clock inputs. If you are using one of these cards, and an external clock source like a digital
tape deck is the master timing source for the project, choose the Trigger and Freewheel option.
The clock input on the audio card guarantees that there is no drift between the time code and audio
playback.
To Set the Audio Playback Option
1. Choose Options > Audio, and click the Advanced tab.
2. Check the desired option from the Synchronization list.
3. Click OK.
Audio playback under time code sync is handled according to the setting you chose.
SMPTE/MTC Sync and Full Chase Lock
When using SMPTE/MTC Sync with full chase lock, the first time you play any audio the pitch may
fluctuate wildly for up to 30 seconds. Also, you may occasionally note the pitch of the audio sounding
consistently high or low pitch.
A simple analogy makes this behavior easy to understand: Synchronizing audio to SMPTE/MTC is a
lot like trying to get even and stay neck-and-neck with another car on the freeway. If the car is ahead
of you, you need to drive faster to catch up to it. If it's behind you, you have to slow until the car
catches up to you. Once the two cars are neck-and-neck, you can simply keep going at the same
speed, unless the other car changes its speed. If the other car speeds or slows, you must speed or
slow too.
The first time you play audio under SMPTE/MTC Sync, the audio clock has to get even with the
external clock. This could mean racing ahead, which raises the pitch of the audio, or stepping on the
Option How it works
Trigger and freewheel Audio event playback is started (or triggered) at the exact time code, but then
the audio plays at its own internal rate (or freewheels). When audio freewheels,
it can gradually drift from the time code due to variations in the time code signal.
Full chase lock The speed of audio event playback is continually adjusted to stay in sync with
the time code. If the external clock drifts or changes rate, SONAR adjusts the
audio playback speed to stay in sync. This adjustment may introduce slight
pitch changes, but those changes will be negligible if the external clock is
reasonably steady.
Table 172.