Hi, I sent this reply to 
Dave Weiner, but it hasn't come up, so I thought I'd send it again with a few corrections and amendments:
Having "looped" (dialog replacement, a.k.a. ADR) quite a number of different actors on the TV series "Combat" as an assistant editor at MGM, the actors would come to loop stage where sound editors had delivered the prepared loops.  Some loops were sound only where the actor would just listen to the track before recording it with three cue pops leading to the downbeat, and I was listening in the booth hearing both the original and the new track mixed together in order to "call sync".  But some loops were with picture with streamers and pops cueing the incoming line.  Some actors would never be able to lip-sync well, and that was when I had to do sprocket edits later (four sprockets per frame) to make them fit the picture.  In tribute, Vic Morrow would always do them in one take.  Most of the looping was done to replace dialogue that had been recorded on location on the back lot where exterior sources of sound would ruin the track (ie., planes, cars,
 trucks, etc.).  Then, there were times when the actor didn't give the reading that the director wanted, so they'd have to make a new track.  Of course, I know that in some features, a foreign actor was unintelligible, so all of their lines would be replaced with another actor.  As far as recording on a sound stage (that's why they were called that), when I started at Desilu, Glen Glenn Sound was doing a lot of the recording on their own 10 1/2" reel to reel 1/4" tape machines parked outside the stages, but later on, they had direct lines to the sound department for dialog recording. In my experience, the Nagra finally became the recording deck of choice whether on location or on sound stage, because of its small size, excellent fidelity and dependability.   In some of the foreign Italian features that Selmur, the "Combat" producing company bought to release here, we redubbed them on the MGM mixing stages, adding additional wild tracks and
 correcting the Italian loop lines for better synch.  But, those lines always sounded phony and lifeless.  I think our loops were more carefully recorded and made to sound more like what the original should have been.  Also, if time permitted, the sound recordist on location would ask to make a wild track if he knew that a track was "dirty".  Then, they'd wait for a quiet moment to record.  That track would always be better because it was the same acoustic condition as all the other good tracks recorded with camera.  However, as I mentioned, some actors were better at doing it as close to the original as possible.  And, I always had my butt splicer at hand to fix them.  If you had good sound editors on the job, they could carefully fill the background of the loop with  "atmosphere" to match the live tracks, so it wouldn't "go dead" behind the loop.  Artfulness is a quality that isn't always recognized in a such highly technical area, although
 today, sound editors (MPSE) do give their own awards as does the Academy.
--- On Thu, 4/26/12, Bob Olhsson <[log in to unmask]> wrote:

From: Bob Olhsson <[log in to unmask]>
Subject: Re: [ARSCLIST] Movie sound ( was Re: [ARSCLIST] "Life" IN recordings (or lack thereof),
To: [log in to unmask]
Date: Thursday, April 26, 2012, 9:25 AM

Singing and dancing has almost always been shot to a playback.

Bob Olhsson 

-----Original Message-----
From djwein: 
As far as I've read, due to low budgets, EVERY Soundie had the music
recorded first and then the filming was lipsynched to the playback -