Posted by Richard Crowley on 10/31/07 13:10

"rakmanenuff" wrote...
> I've watched people film music videos, and it's often the
> artist miming to a loud "ghetto blaster" at some location.
> Now.. I don't doubt that pro cameras have fairly accurate
> timing, and I guess professionals use playback devices that
> are in sync, but normal portable stereos don't always play
> back the music in the exact tempo of the original master.

This is regularly discussed by the professionals who do it
over on the newsgroup rec.arts.movies.production.sound
Yes, they frequently play the song from a specially-prepared
copy that has a mono version on one track, and timecode
on the other track. The musos/actors listen to the audio
track, and the TC track is synced with the camera(s).

> I don't make pro videos, only fun ones with a cheap pocket-
> size digicam, but the tempo discrepancies are really bad.
>
> How do people overcome this problem?

Sinply put: They cut the video to the music which is
layed into the sound track whole and never touched.

> I can think of a few ways of doing it, like timestretching
> the audio.

It is nearly impossible to stretch (or compress) the audio
without leaving ugly artifacts.That is why it is typically
not done. By comparison, it is trivial to cut the video
to match the music.

> Otherwise there might be a lot of tedious action with the
> razorblade or scissors.

Assuming you don't mean that literally. Yes, good music
videos take a lot of creative (and tedious) video editing to
match the music. But computers and non-linear editing
(NLE) video editing software are used.

> But I'm curious to hear how others do this. Is there a
> "beat detector"/ alignment/ snap type plugin or function
> that syncs up one piece of audio to another?

There are beat-detectors that will align video cuts with
the music, but generally the music is the reference and
the video is cut to it.

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