Autodesk 64006-051108-9001 User Guide - Page 73

The Image Tab 65 Eliminate Top, Bottom Field- removes every other line of the original source and interpolates extra lines if needed. Selecting either option generally produces sharp images because it eliminates the motion blur effect of interlacing and produces similar final results. Intelecine - Intelecine is the exclusive Cleaner "intelligent" inverse telecine 3:2 pulldown removal option that removes the extra pulldown frames added to movies when they are transferred from 24 fps film to 29.97 fps NTSC video. Unlike other forms of inverse telecine, the Cleaner Intelecine feature can detect and automatically adjust to edits in the video. Auto - Automatically determines the best de-interlacing method for the video. To quickly check if your source file contains 3:2 pulldown frames, find a sequence without any edits and step through it frame by frame. You should see a repeating pattern of three progressive frames followed by two interlaced frames. Note: If you use the Top or Bottom de-interlacing options and get a slight stutter in the video, you may be seeing frame duplication resulting from source material that was shot on film and transferred to video. In these cases, capture the source video at full-frame size and rate and use the Intelecine option. See the next section for more details. Processing NTSC Movies Shot on Film The frame rate of film is 24 fps; the frame rate of NTSC video is 29.97 fps. When movies are translated between film and NTSC video, extra frames are added to compensate for this difference. These new frames are created by a machine called a telecine, and the process is often referred to as introducing a 3:2 pulldown into the material. There are four important reasons to return your material to its original frame rate before encoding it: •Leaving the pulldown frames in your material looks bad. These extra frames have strong interlace lines in areas of rapid movement. This effect is similar to normal interlacing, except it is more pronounced and displays poorly on a computer screen. •Blended frames encode poorly because of the strong interlacing artifacts present in them. •Extra frames do not have unique information in them. They are simply blends of two other frames in the source. These frames are important for NTSC television, which requires 29.97 fps, but are totally useless for desktop video, which does not have this constraint. •A frame rate of 24 fps is 20% less frames (and therefore less data) than a frame rate of 29.97 fps. Encoding the original 24 fps source produces smaller/higher quality files.