CAKEWALK Cakewalk SONAR, Руководство пользователя

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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 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.