Progressive segmented Frame (PsF) is a High Definition mastering video format used to store progressive content on interlaced media. Unlike broadcast video formats, PsF is not intended for direct delivery to end users. PsF was designed as a unified world-wide standard to simplify the process of converting cinematic content to the various video standards, and as means for video exchange between the networks and broadcasters worldwide.[1]
With PsF, a progressive frame is separated into "segments", with the odd lines in one segment and the even lines in the other segment. This allows for a progressive picture to be processed through the same common electronic circuitry that is used to store, process and route interlaced video. The primary difference between PsF and interlaced video is motion. In PsF there is no motion between the two segments that make up the "progressive" frame while in interlaced there is typically motion between the "fields". The signal is played back at 1080i but when viewed, it is seen as true 1080p
PsF and 2:2 pulldown
Progressive segmented frame technique is equivalent to 2:2 pulldown pattern. It seems that "PsF" is used for material originated on video, while "2:2 pulldown" seems to be used for telecine process, and in broadcast.
Charles Poynton, an authority in digital television, makes the following remark in his book: "Proponents of [PsF] scheme claim compatibility with interlaced processing and recording equipment, a dubious objective in my view."[2] He does not question the usefulness of 2:2 pulldown scheme for broadcast purposes. Poynton explains the technique used to transfer movies to video as follows: "Film is transferred to 576i video using 2:2 pulldown: Each film frame is scanned into two video fields (or frames); the film is run 4% fast."
Examples of using PsF for acquisition
Progressive segmented frame technology is used in HDCAM and XDCAM video cameras, including famous CineAlta camera. This camera was used by George Lucas to shoot the Star Wars, Episode 2 movie.
Examples of using PsF for mastering
Terminator 2: Extreme Edition
One of the examples of practical usage of PsF is the "Terminator 2: Extreme Edition" DVD release. Earlier releases for videotape, LaserDisk and DVD were done by transferring the original theatrical release to 60i video using 2:3 pulldown scheme, then by editing the resulting video. The final result was interlaced video with 2:3 cadence being constantly interrupted. The broken cadence made no difference for analog television, but became a problem when progressive scan TV sets with 2:3 cadence detection became commonplace.
Considering tremendous popularity of the "Terminator 2", Artisan and THX performed a completely fresh transfer of the movie to digital form in 2003. They started with creating a new high definition digital master by converting original 24fps film to 1080PsF24 format and recording it to HD-D5 videotapes. Usage of progressive segmented frame allowed creating a digital master that was identical to original film, and made possible to perform all digital editing in 24p mode.[3] It is also worth nothing that this digital master appears to be used for 2006 Blu-Ray transfer of the movie.[4]