Progressive segmented Frame
Encyclopedia
Progressive segmented Frame (PsF, sF, SF) is a scheme designed to acquire, store, modify, and distribute progressive-scan
video using interlaced equipment and media.
With PsF, a progressive frame is divided into two segments, with the odd lines in one segment and the even lines in the other segment. Technically, the 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. This technique allows for a progressive picture to be processed through the same electronic circuitry that is used to store, process and route interlaced video.
The PsF technique is similar to 2:2 pulldown, which is widely used in 50 Hz television systems to broadcast progressive material recorded at 25 frame/s, but is rarely used in 60 Hz systems. The 2:2 pulldown scheme had originally been designed for interlaced displays, so fine vertical details are usually filtered out to minimize interline twitter. PsF has been designed for transporting progressive content and therefore does not employ such filtering.
The term progressive segmented frame is used predominantly in relation to high definition
video. In the world of standard definition video, which traditionally have been using interlaced scanning, it is also known as quasi-interlace or progressive recording.
Not everyone welcomed the PsF standard, however. 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." William F. Schreiber, former Director of the Advanced Television Research Program at MIT
, suspected that the continued advocacy of interlaced equipment originated from consumer electronics companies that were trying to get back the substantial investments they had made in obsolete technology.
videotapes. This allowed for the creation of a digital master that was nearly identical to the original film, and made it possible to edit digitally at the native frame rate. The same digital master appears to be used for the 2006 Blu-ray Disc
transfer of the movie.
PsF has been recognized by Recommendation ITU-R BT.709 as a legitimate way to transport progressive frames within an interlaced system. 25PsF and 30PsF rates have been added to the specification in addition to the more established 24PsF. "Fractional" frame rates, having the above values divided by 1.001, are also permitted; the resulting 23.976PsF and 29.97PsF rates are used in 60 Hz systems.
PsF became a means of initial image acquisition in professional Sony video cameras. It is employed in HDCAM
and XDCAM
video cameras, including the HDW-F900 CineAlta
camera which was used by George Lucas
for creating Star Wars, Episode 2
, and by Alexander Sokurov
for creating Russian Ark
fully in the digital domain.
PsF is utilized in some DV
, HDV
and AVCHD
camcorders for 25-frame/s and 30-frame/s progressive-scan recording, and can be called Progressive recording (Sony), Progressive scan mode (Sony), Frame mode (Panasonic and Canon), Digital Cinema mode (Panasonic) or Cinema mode (Canon). Consumer and many professional camcorders do not use PsF to record 24-frame/s video; instead they either record it natively in progressive form or apply 2:3 pulldown.
The operating guide for a 60 Hz ("NTSC") Sony DCR-HC96 camcorder describes the progressive recording mode as follows:
The booklet for the 50 Hz ("PAL") Sony DSR-PD175P camcorder describes its progressive recording mode as follows:
to reduce amount of chroma
information in a video, taking advantage of the human visual system's lower acuity for color differences than for luminance. Such a reduction improves compressing the video signal, which is always desirable because of storage and transmission limitations.
To ensure compatibility with interlaced-based systems, chroma information in PsF video is often recorded in interlaced format, despite that the content is progressive. This may result in interlaced artifacts noticeable on colored objects.
Progressive scan
Progressive scanning is a way of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence...
video using interlaced equipment and media.
With PsF, a progressive frame is divided into two segments, with the odd lines in one segment and the even lines in the other segment. Technically, the 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. This technique allows for a progressive picture to be processed through the same electronic circuitry that is used to store, process and route interlaced video.
The PsF technique is similar to 2:2 pulldown, which is widely used in 50 Hz television systems to broadcast progressive material recorded at 25 frame/s, but is rarely used in 60 Hz systems. The 2:2 pulldown scheme had originally been designed for interlaced displays, so fine vertical details are usually filtered out to minimize interline twitter. PsF has been designed for transporting progressive content and therefore does not employ such filtering.
The term progressive segmented frame is used predominantly in relation to high definition
High-definition video
High-definition video or HD video refers to any video system of higher resolution than standard-definition video, and most commonly involves display resolutions of 1,280×720 pixels or 1,920×1,080 pixels...
video. In the world of standard definition video, which traditionally have been using interlaced scanning, it is also known as quasi-interlace or progressive recording.
History
PsF was designed to simplify the conversion of cinematic content to different video standards, and as a means of video exchange between networks and broadcasters worldwide. Brought to life by the movie industry in the end of 1990s, the original PsF specification was focused on 24 frame/s content, resulting in existing interlaced equipment having to be modified for 48 Hz scanning rate in order to work properly with 24 frame/s content.Not everyone welcomed the PsF standard, however. Some industry observers maintained that native 24p processing would have been a better and cleaner choice. Charles Poynton
Charles Poynton
Charles A. Poynton is a technical consultant and writer based in Toronto, Canada. He is best known for his seminars on digital video systems and his two books, A Technical Introduction to Digital Video and Digital Video and HDTV: Algorithms and Interfaces...
, 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." William F. Schreiber, former Director of the Advanced Television Research Program at MIT
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
, suspected that the continued advocacy of interlaced equipment originated from consumer electronics companies that were trying to get back the substantial investments they had made in obsolete technology.
Usage
Despite 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 the 2003 transfer of the film "Terminator 2" to DVD, performed by Artisan and THX. The original 24 frame/s movie was converted to PsF format and recorded to HD-D5D5 HD
D-5 is a professional digital video format introduced by Panasonic in 1994. Like Sony's D-1 , it is an uncompressed digital component system , but uses the same half-inch tapes as Panasonic's digital composite D-3 format...
videotapes. This allowed for the creation of a digital master that was nearly identical to the original film, and made it possible to edit digitally at the native frame rate. The same digital master appears to be used for the 2006 Blu-ray Disc
Blu-ray Disc
Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...
transfer of the movie.
PsF has been recognized by Recommendation ITU-R BT.709 as a legitimate way to transport progressive frames within an interlaced system. 25PsF and 30PsF rates have been added to the specification in addition to the more established 24PsF. "Fractional" frame rates, having the above values divided by 1.001, are also permitted; the resulting 23.976PsF and 29.97PsF rates are used in 60 Hz systems.
PsF became a means of initial image acquisition in professional Sony video cameras. It is employed in HDCAM
HDCAM
HDCAM, introduced in 1997, is an High-definition video digital recording videocassette version of Digital Betacam, using an 8-bit DCT compressed 3:1:1 recording, in 1080i-compatible downsampled resolution of 1440×1080, and adding 24p and 23.976 PsF modes to later models...
and XDCAM
XDCAM
XDCAM is a a series of products for digital recording using random access solid-state memory media, introduced by Sony in 2003. Four different product lines — the XDCAM SD, XDCAM HD, XDCAM EX and XDCAM HD422 — differ in types of encoder used, frame size, container type and in...
video cameras, including the HDW-F900 CineAlta
CineAlta
Sony's CineAlta 24P HD Cameras are a series of professional digital video cameras that offer many of the same features of a 35mm motion picture film camera.- Concept :...
camera which was used by George Lucas
George Lucas
George Walton Lucas, Jr. is an American film producer, screenwriter, and director, and entrepreneur. He is the founder, chairman and chief executive of Lucasfilm. He is best known as the creator of the space opera franchise Star Wars and the archaeologist-adventurer character Indiana Jones...
for creating Star Wars, Episode 2
Star Wars Episode II: Attack of the Clones
Star Wars Episode II: Attack of the Clones is a 2002 American epic space opera film directed by George Lucas and written by Lucas and Jonathan Hales. It is the fifth film to be released in the Star Wars saga and the second in terms of the series' internal chronology...
, and by Alexander Sokurov
Alexander Sokurov
Alexander Nikolayevich Sokurov is a Russian filmmaker. His most significant works include a semi-documentary, Russian Ark , filmed in a single unedited shot, and Faust , which was honoured with the Golden Lion, the highest prize for the best film at the Venice Film Festival.- Life and work...
for creating Russian Ark
Russian Ark
Russian Ark is a 2002 Russian historical drama film directed by Alexander Sokurov. It was filmed entirely in the Winter Palace of the Russian State Hermitage Museum using a single 96-minute Steadicam sequence shot...
fully in the digital domain.
PsF is utilized in some DV
DV
DV is a format for the digital recording and playing back of digital video. The DV codec was launched in 1995 with joint efforts of leading producers of video camcorders....
, HDV
HDV
HDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon and Sharp...
and AVCHD
AVCHD
AVCHD is a file-based format for the digital recording and playback of high-definition video....
camcorders for 25-frame/s and 30-frame/s progressive-scan recording, and can be called Progressive recording (Sony), Progressive scan mode (Sony), Frame mode (Panasonic and Canon), Digital Cinema mode (Panasonic) or Cinema mode (Canon). Consumer and many professional camcorders do not use PsF to record 24-frame/s video; instead they either record it natively in progressive form or apply 2:3 pulldown.
The operating guide for a 60 Hz ("NTSC") Sony DCR-HC96 camcorder describes the progressive recording mode as follows:
The booklet for the 50 Hz ("PAL") Sony DSR-PD175P camcorder describes its progressive recording mode as follows:
Encoding of color information
Most video formats including professional ones utilize chroma subsamplingChroma subsampling
Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance....
to reduce amount of chroma
Chrominance
Chrominance is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal . Chrominance is usually represented as two color-difference components: U = B' − Y' and V = R' − Y'...
information in a video, taking advantage of the human visual system's lower acuity for color differences than for luminance. Such a reduction improves compressing the video signal, which is always desirable because of storage and transmission limitations.
To ensure compatibility with interlaced-based systems, chroma information in PsF video is often recorded in interlaced format, despite that the content is progressive. This may result in interlaced artifacts noticeable on colored objects.
Variants
- 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.
- 25PsF (1080sf25, 1920x1080/25/1:1SF) is used in 50 Hz systems for production that originates on video and is targeted for television distribution.
- 29.97PsF (1080sf29, 1920x1080/29.97/1:1SF) formats are sometimes used in 60 Hz systems for sitcoms and music shows. 29.97PsF as well as 30PsF (30p, 1080sf30, 1920x1080/30/1:1SF) formats are gaining popularity as an acquisition format for Web video delivery, because most video hosting web sites cannot stream video with rates higher than 30 frame/s.