Starting in spring 1948, actors were filmed on large soundstages mouthing to a playback of the dialogue soundtrack. Disney had previously used live-action reference on "Snow White and the Seven Dwarfs", "Pinocchio", and "Fantasia", but as part of an effort to keep the production cost down, the footage was used to check the plot, timing, and movement of the characters before animating it. The footage was then edited frame-by-frame onto large Photostat sheets to duplicate, in which the animators found too restrictive as they were not allowed to imagine anything that the live actors did not present since that kind of experimentation might necessitate changes and cost more money. Additionally, the animators were instructed to draw from a certain directorial perspective to avoid difficult shots and angles. Frank Thomas explained, "Anytime you'd think of another way of staging the scene, they'd say: 'We can't get the camera up there'! Well, you could get the animation camera up there! So you had to go with what worked well in live-action."