The History Of The Term B-Roll
If you are familiar with the term b-roll in its contemporary usage, you know it refers to alternate footage that is not part of the main action. It is used to illustrate something being spoken about or to cover an edit in the main action. An example would be including footage of children playing that is shown while a person is talking about playground safety. Another example would be a shot of an interviewer listening intently that is used to cover an edit where the interviewee went off on a tangent before completing a thought. The tangential material is cut out and the b-roll hides the edit.
The origins of the word stretch back a little further. In the world of film, whenever an optical effect like a wipe or dissolve is created, the footage needs to be separated onto 2 film rolls marked A and B. Each roll must be exactly the same length. When there is an image on the A-roll the corresponding B-roll will have black frames and vice versa. Where a transition is needed, the 2 pieces of footage will overlap. To create the final film, both rolls are sent through an optical printer which copies the images onto a new piece of film. When the A roll pass is finished, the new negative is rewound and the process is repeated with the B roll. In the places where there are transitions, the optical printer will fade one roll out and the other roll in to blend them together.
The early days of video had much the same needs. Before the advent of digital editing, whenever a transition was needed between two clips, the video had to be recorded onto 2 seperate tapes. The tapes where played back in sync and the output of the tape decks was fed into a video switcher. When the program reached a point where a transition was needed, the video on both tapes overlapped and the switcher was set to make a transition between the 2 sources. The output of the switcher was recorded on a third tape deck and this became the program master tape.
Much of the television work that was produced on video was for news programs. (Movies and sitcoms were and are usually shot on film and transferred to video.) This type of programming generally consists of interviews. To prepare video segments, the editor would create an A-roll tape that featured the video of the people being interviewed. When this A-roll was finished, a B-roll was created that contained secondary footage (usually without sound) that was designed to either cover over the edits in the A-roll or illustrate what was being talked about. Over time getting footage for the B-roll ended up being referred to as ‘shooting B-roll.’
I do not know if that little bit of trivia is helpful in any way, but it is something I find interesting.
