Reference Guide

829
SMPTE/MIDI Time Code Synchronization
Synchronizing Your Gear
brakes, which lowers the pitch of the audio. These fluctuations continue until SONAR matches its
playback speed to the external clock, which usually takes no more than 30 seconds. The stable
playback speed, by the way, may be slightly faster or slower than the normal audio playback speed,
resulting in a slight change in the pitch of the audio. Here’s the best way to address this problem:
• Start each new SONAR session by playing some audio under SMPTE/MTC Sync.
• Let the audio play for 30 seconds or until all audio pitch fluctuations stop.
Once this procedure is complete, SONAR knows the difference in rates between the external time
code and the audio clock on your sound card. For the rest of the session, SONAR will start playback
closely in sync, without any drastic pitch changes.
If the external timing source were 100 percent stable, the audio would stay in sync with the external
clock. Unfortunately, no timing source is perfect. Therefore, every once in a while after playback has
started, SONAR may need to vary the playback speed by a tiny amount to stay even with the time
code. If the time code signal is unstable (as might be the case from an analog source), these
variations can cause noticeable changes in audio pitch, which can in turn cause audible audio
distortion.
Troubleshooting SMPTE/MTC Sync
The most common problems with SMPTE/MTC Sync, and ways to correct or avoid them, are shown
in the following table:
Problem What to do
The tape is striped incorrectly Check the tape stripe using your time code generator and, if
necessary, restripe the tape.
The MIDI interface isn’t producing MIDI
Time Code
Use utility programs that come with your MIDI interface to make
sure that the time code stripe is being received (sometimes you
must enable a Time Code Sync option). Check the MIDI
interface settings to make sure that MIDI Time Code is being
generated.
The frame rate is set incorrectly The frame rate on the stripe must match the frame rate you set in
SONAR.
The offset is set incorrectly The offset you enter in SONAR must match the start time of
recorded material on the tape.
SONAR is not configured correctly Verify and/or repeat the steps in “To Configure SONAR to Sync
to SMPTE/MTC” on page 826.
Table 173.