Progressive segmented frame: Difference between revisions

Revision as of 23:05, 16 January 2008

Revision as of 00:14, 17 January 2008

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== History ==

Originally, PsF washas not meant neither for [[High-definition_television|broadcast]] nor for usage in home video devices. PsF wasbeen designed as a standard to simplify the conversion of cinematic content to different video standards, and as means of video exchange between networks and broadcasters worldwide.<ref>{{cite web|url=http://www.tech-notes.tv/Jim/Articles/24vs48sF.html|title=Jim Mendrala, A discussion of 24p frame and the new 48sF frame format}}</ref> Brought to life by the movie industry in the end of 1990-ies, the original PsF specification was focused on 24 fps content. Existing interlaced equipment had to be modified for 48i scanning rate in order to work properly with PsF video.

With PsF, a progressive frame is sliced into two "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 electronic circuitry that is used to store, process and route interlaced video. Technically, progressive segments are equivalent to interlaced fields, but unlike native interlaced video, there is no motion between the two fields that make up the video frame, both fields represent the same instant in time.

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Not everyone welcomed the PsF standard. Some industry observers maintained that native 24p processing would have been a better and cleaner choice. Others accused Sony Pictures in lobbying products of its parent company, Sony Corporation, which at that time was producing interlaced equipment. 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."<ref>{{cite web|url=http://books.google.com/books?id=ra1lcAwgvq4C&pg=RA1-PA62&sig=8ZAl0RqzUYnyxQSmjxiIw4ZJDbE|title=Charles Poynton, Digital Video and HDTV: Algorithms and Interfaces}}</ref>

PsF technology is implemented in [[HDCAM]] and [[XDCAM]] video cameras, including famous [[CineAlta]] camera that was used by George Lucas for the [[Star_Wars_Episode_II:_Attack_of_the_Clones|Star Wars, Episode 2]] movie.

== PsF vs. 2:2 pulldown ==

Progressive segmented frame technique is equivalent to [[Telecine|2:2 pulldown]] pattern, which is widely used in PAL/SECAM television. As Charles Poynton explains, "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."

It seems that "PsF" is used for acquisition and mastering of high definition video, while "2:2 pulldown" is used to describe a particular [[Telecine|telecine]] pattern, and as a broadcast term both for standard definition and high definition.

== 24PsF ==

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24PsF (48sF, 1080sf24, 1920x1080/24/1:1SF) is the original PsF specification, which is used exclusively in professional equipment for film-to-video transfer, mastering and exchange between networks. This may be the first universal video standard which transcends continental boundaries, an area previously reserved for film.<ref>{{cite web|url=http://www.filmmaking-careers.com/film-production.html|title=Steve Wiedemann, 24/P HDTV: The Fall of Film Production}}</ref>

PsF technology is implemented in [[HDCAM]] and [[XDCAM]] video cameras, including famous [[CineAlta]] camera that was used by George Lucas for the [[Star_Wars_Episode_II:_Attack_of_the_Clones|Star Wars, Episode 2]] movie.

One of the documented examples of 24PsF usage is 2003 transfer of the "Terminator 2" movie to DVD. Artisan and THX 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.<ref>{{cite web|url=http://www.dtvforum.info/lofiversion/index.php/t16581.html|title=Terminator 2: Extreme Edition}}</ref> The same digital master appears to be used for 2006 Blu-Ray transfer of the movie.<ref>{{cite web|url=http://bluray.highdefdigest.com/terminator2.html|title=Terminator 2: Judgment Day (Blu-ray)}}</ref>

One of the documented examples of 24PsF usage in digital mastering is 2003 transfer of the "Terminator 2" movie to DVD. Artisan and THX 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.<ref>{{cite web|url=http://www.dtvforum.info/lofiversion/index.php/t16581.html|title=Terminator 2: Extreme Edition}}</ref> The same digital master appears to be used for 2006 Blu-Ray transfer of the movie.<ref>{{cite web|url=http://bluray.highdefdigest.com/terminator2.html|title=Terminator 2: Judgment Day (Blu-ray)}}</ref>

== 25PsF ==

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23PsF (1080sf23, 1920x1080/23.98/1:1SF) and 29PsF (1080sf29, 1920x1080/29.97/1:1SF) frame rates are often used for HD production in organizations that also produce standard definition 525 line services (i.e. at 59.94Hz).

== PsF vs. 2:2 pulldown ==

Progressive segmented frame technique is equivalent to [[Telecine|2:2 pulldown]] pattern, which is widely used in PAL/SECAM television. As Charles Poynton explains, "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."

It seems that "PsF" is used for acquisition and mastering of high definition video, while "2:2 pulldown" is used to describe a particular [[Telecine|telecine]] pattern, and as a broadcast term both for standard definition and high definition.

==References==