Progressive segmented frame

Progressive segmented Frame (PsF, sF, SF) is a High Definition mastering video format designed to acquire, store, modify and distribute progressive content using interlaced equipment and media.

History

PsF has been designed to simplify the conversion of cinematic content to different video standards, and as means of video exchange between networks and broadcasters worldwide. [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] Brought to life by the movie industry in the end of 1990s, the original PsF specification was focused on 24 fps content. Existing interlaced equipment had to be modified for 48 Hz 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.

Not everyone welcomed the PsF standard. Some industry observers maintained that native 24p processing would have been a better and cleaner choice. Charles Poynton, an authority in digital television, made the following remark in his book: "Proponents of [PsF] scheme claim compatibility with interlaced processing and recording equipment, a dubious objective in my view." [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] William F. Schreiber, former Director of the Advanced Television Research Program at MIT, suspected that the continued advocacy of interlaced equipment originated from foreign-owned consumer electronics companies that were trying to get back the substantial investments they foolishly had made in obsolete technology. [cite web|url=http://www.cinemasource.com/articles/hist_politics_dtv.pdf|title=The history and politics of DTV]

Despite of the criticism, PsF quickly became a de-facto standard for high quality film-to-video transfer. One of the documented examples of PsF usage is 2003 transfer of the "Terminator 2" movie to DVD, performed by Artisan and THX. The original 24-fps movie was converted to PsF format and recorded to HD-D5 videotapes. This allowed creating a digital master that was identical to original film, and made possible to perform all editing digitally at native frame rate. [cite web|url=http://www.dtvforum.info/lofiversion/index.php/t16581.html|title=Terminator 2: Extreme Edition] The same digital master appears to be used for 2006 Blu-ray Disc transfer of the movie. [cite web|url=http://bluray.highdefdigest.com/terminator2.html|title=Terminator 2: Judgment Day (Blu-ray)]

PsF became a means of initial image acquisition in professional Sony video cameras. It is employed in HDCAM and XDCAM video cameras, including famous HDW-F900 CineAlta camera that was used by George Lucas for creating , and by Alexander Sokurov for creating Russian Ark fully in the digital domain.

PsF has been recognized by Recommendation ITU-R BT.709 as a legitimate way to transport progressive signal within an interlaced system. 25PsF and 30PsF rates have been added to the specification in addition to well-established 24PsF. "Fractional" frame rates, having the above values divided by 1.001, are also permitted, which results in 23.98PsF and 29.97PsF rates, currently used in 60 Hz systems.

24PsF and 23PsF

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

23PsF (1080sf23, 1920x1080/23.98/1:1SF) frame rate is often used for HD production in organizations that also produce standard definition 525 line services (i.e. at 59.94Hz). [cite web|url=http://www.pro-bel.com/site_documents/Vistek_HD_Poster.pdf|title=pro-bel, Vistek HD Poster]

25PsF

25PsF (1080sf25, 1920x1080/25/1:1SF) is used in 50Hz systems for production that originates on video and is targeted for television distribution.

30PsF and 29PsF

30PsF (30p, 1080sf30, 1920x1080/30/1:1SF) and 29PsF (1080sf29, 1920x1080/29.97/1:1SF) are sometimes used in 60Hz systems for sitcoms and music shows.

At present time, neither 30PsF nor 29PsF are well suited for television distribution, because few TV sets are capable of proper deinterlacing of such video.

Implementations and comparisons

2:2 pulldown

Progressive segmented frame technique is similar to pattern. The latter is widely used in 50 Hz television systems, but is rarely employed in 60 Hz systems as there is very little content of progressive 30 frames/s material.

2:2 pulldown scheme had originally been designed for interlaced devices, so fine vertical details are usually filtered out to minimize interlaced line twitter. PsF has no such filtering.

Frame shutter mode (Sony)

Frame Shutter Mode is the name that Sony came up with after it developed a progressive-scan CCD for video cameras. In Frame Shutter Mode, a camera acquires 15 or 30 (NTSC) or 12.5 or 25 (PAL) independent images per second. These images are output as regular interlaced fields in PsF-like fashion. The result is a progressive-scan signal, which is also compatible with traditional interlaced scanning systems. [cite web|url=http://catalogs.infocommiq.com/AVCAT/images/documents/pdfs/dxc9000.pdf|title=3-CCD Color Video Camera DXC-9000]

Sony uses this technology in professional and consumer products for recording progressive video and for acquiring still images. For example, the DCR-HC96 MiniDV camcorder features 30p progressive mode (its European cousin, DCR-HC96E, has matching 25p progressive mode). This technology is also employed in surveillance and frame-capture applications. [cite web|url=http://www.laserfocusworld.com/display_article/25319/12/ARCHI/none/News/Electronic-imaging-captures-amusement-park-thrills|title=Electronic imaging captures amusement-park thrills]

"F" mode (Canon)

Canon XH-A1 or XH-G1 HDV camcorders have three PSF-like recording modes: 24F and 30F for 60Hz systems and 25F for 50Hz systems.

Unlike PsF that has been designed for high-end applications and requires a 1920x1080 frame size, HDV resolves to a 1440x1080 frame size. The videocameras use "video rates" not "film rates", therefore 24F is similar to 23PsF, while 30F is similar to 29PsF.

"PF" mode (Canon)

Canon HV20/HV30 HDV and HF10/HF100 AVCHD consumer camcorders use "PF" notation for progressive shooting modes. In 50 Hz markets, PF25 mode allows recording progressive video in 25PsF fashion. In 60 Hz markets, PF30 mode allows recording in 29PsF fashion. [cite web|url=http://www.avchduser.com/articles/canon_progressive_modes.jsp|title=Canon 24P, 25F, 25P, 30F, 30P modes explained]

Unlike HDV cameras, the HF10/100 provides "Full HD" 1920x1080 frame at its highest available quality setting.

References

Bibliography

* [http://www.leitch.com/resources/whitePapers/Whatis24P.pdf What is 24P?"]