Note: viewers with low resolution monitors are going to have to do some horizontal scrolling on this webpage in order to preserve the images.
Below is a screenshot of a wavform. We are going to cut 2 frames worth of audio out right in the center, one on either side of the vertical line.
Below is the edited wavform, missing those 2 frames.
It doesn't take a rocket scientist to understand that there will be something lost on an edit like that, for the buildup of the word "shot" is missing from this sentence. Now granted most reel changes are not mid sentence, but there are enough of them that are, or have gunshots or music where two differing wavforms will cause an abrupt jump in the audio as was simulated above.
CLICK HERE to download the unaltered video.
CLICK HERE to download video missing those 2 frames.
(Sorry folks, QuickTime format only.)
Now bear in mind too that this demo was based upon 30 frames per second video/audio. Since film runs at 24 frames per second, technically a loss of 2 frames would be losing approximately another half of a 30FPS video frame, so the effect is even worse on a film print. Furthermore, if a "butt" splice is made, the effect is exactly what you hear here (plus in all probability a small "pop"). If an overlap splice is made like is shown in the "tips" section, the end effect is very similar to a quick crossfade at the join, which is much more pleasing and often completely unnoticeable.
Bottom line: when building prints if there is noticeable wavform
difference on the last frame and first frame into the leader, do not cut
ID frames.
If the wavform looks pretty much the same, it is generally safe
to cut the ID frames.