The DIY concept is to align the HW audio file to the iPhone or Camcorder audio. Then the Video audio track is replaced with the "pure" HW audio. Thus, any poor audio and/or background noise picked up by the camera's mic is removed from the final video.
There are 2 areas typically involved with synchronization:
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Getting the start of the audio and video files to line up. Since it is difficult to start both HW Recorder and the Video Recorder at precisely the same time, iMovie can be used to align the start.
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For long recordings, clock differences may exist between your computer and the iPhone or camcorder. Thus if the beginning is perfectly aligned, the end may be offset. If the difference is noticeable during playback (the fingers will not match the sound) you may need to adjust the HW audio or the video.
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The process to sync audio to video is to first determine the offset that needs to be corrected, which is explained on this page. Then adjust the timing:
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The simplest approach is to adjust the HW audio (wav file) using Audacity without changing the pitch of any of the notes. See
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An alternate approach is to increase or decrease the total length of the video using iMovie's Speed Editor. See
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In the following example, the .wav file is the recorded audio from HW. The m4v is video recorded from the iPhone. Both were imported into iMovie. The mp4 inserted below is the result from iMovie (Note: I cut about 90 seconds out of the middle to keep it short).
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If you use a different movie editor or video recorder, the synchronization concept should be similar.
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I started and ended with several quick notes to make it easy to identify the notes at the beginning and end and determine any offset that may exist. 2 or 3 notes should be sufficient. They would eventually be edited out and a Title and Introduction can be added.
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Demo for syncing of Hauptwerk audio vs iPhone video
iMovie with video clip imported directly from iPhone and .wav file as imported into iMovie after saving from HW is shown below.
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The files are shown below after loading into iMovie Editor and deleting 4 or 5 seconds to account for the time required to start the iPhone Camera and then the HW Recorder until ready to start playing. The HW audio is aligned with the audio from the iPhone. I temporarily increased the volume level to make it easier to see the waveforms.
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Sync Offset when recording video with Hauptwerk
The offset at the end after aligning the start is shown below. The recording was about 3 minutes. Since the differrence is only about one or two video frames, I adjusted the HW audio to split the difference at the beginning and end. After playing back, this little bitty offset is not discernable. Other tests I ran had as much as 0.3 seconds offset over 5 minutes, which was very noticeable. This requires adjusting the timing as defined on the next three pages.
