Synchronizing Tracks

Here are some tips if you're trying to record multiple tracks and synchronize them:


 * When recording your first track, "count in" by tapping your microphone, pickup, etc... or import a count in from another file. Short, quick, percussive sounds at an even tempo is key here. Generating a click-track in a newer version of Audacity will work well, even if it is only a couple of measures.


 * On all subsequent tracks, count in your rhythm, in synch with the playback of the first track's count, using the tapping method described above.


 * You can now zoom in on your first track and subsequent tracks at the count-in. Pay particular attention to your last count-in beat (If you've counted in well, your last beat should definitely be in synch). Line up the beginning of the last beat in all subsequent tracks with the corresponding one from the first track, using the time shift tool.


 * Your audio should now be synchronized. If not, adjustments should be minor, unless your count or performance was way off ... in which case, nothing can help you, except to re-record. When your song is finished, remove your count-in beats.

Reducing the Audacity sample rate may eliminate this speed "drift" problem. Here is an example of the effect and the sizes of the errors: On a 2GHz Dell PC with Windows XP and onboard sound, a sample rate of 64000 gave timing record/playback errors of 0.9 percent between the first track and the subsequent track. Tracks synchronised at start of recording would therefore be out of synch by one second after a minute or two. Reducing the sample rate from 64000 to 48000 resulted in tracks that remained in synch to within 0.0001s over a 5 minute period.
 * If your tracks drift out of synch gradually, you may be having problems with skipping or with poor-quality hardware.


 * You can always expect a small (but constant) time delay on subsequent tracks. This is due to fixed delays in the analogue - digital conversion processes as described in Audacity (1.2.6) application Help/Other/Preferences/Audio I/O. The application help suggests using the TimeShift tool to slide tracks back into synch. An easier and more accurate technique is described below:

(This technique requires confirmation by other users) (can someone explain why this works / what's the theory behind it?)


 * Step 1) In a new project, click the record button, and then the stop button (records a few seconds of silence). Name this first track "Dummy1"


 * Step 2) Repeat step 1 but name the second track "Dummy 2"


 * Step 3) There is no Step 3. You may notice two white arrows at the start of the Dummy2 track. Do NOT use the TimeShift tool to alter that. Leave Dummy1 and Dummy2 exactly as they are.


 * Step 4) Mute both the Dummy tracks.


 * Step 5) Record your first proper music or audio track, with a count-in. This will also show two white arrows at start of the track. Do NOT use timeshift tool - just leave it where it is.


 * Step 6,7..etc) Record subsequent tracks, listening to whichever previous tracks you wish during recording. You should find that the tracks are all exactly synchronised without any TimeShift adjustments being needed.


 * Final Step) You may want to tidy up by deleting the two dummy tracks. All the tracks from step 5, 6, 7 etc will show white arrows at start of track (data starts before time=0). Again, you can tidy up if you wish. When your recording session is completed you can remove these arrows by repeatedly clicking once on Project-Quick Mix after selecting each track individually one track at a time. This preserves exact synchronisation between the tracks by deleting the audio recorded before time=0. Unfortunately this also renames each track as "Mix".