Difference between revisions of "240p video"

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(Created page with 'Taken from http://retrogaming.hazard-city.de/ as a stub Most of the classic systems use a non-interlaced 15kHz output which is compatible to the classic TVs we all had at home i...')
 
 
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Taken from http://retrogaming.hazard-city.de/ as a stub
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In order to save costs and present a stable image on [[interlaced]] displays, most games developed before the year 2000 - and hence all the consoles and arcade games that played them - are rendered in a resolution around 320 pixels wide by 240 lines high, commonly referred as 240p. This video mode is actually a hack on top of the NTSC standard, but it works on all analogue displays.
  
Most of the classic systems use a non-interlaced 15kHz output which is compatible to the classic TVs we all had at home in the 80s and 90s. That's usually between 220 and 240 lines of visible video, along with 280 to 330 pixels of horizontal resolution. In the 90s 480i output became popular. It provides 480 lines of resolution (but only 240 lines per field = at a time) at 640 to 720 pixels of horizontal resolution. A handful of SNES games used this mode (Ranma 1/2), some Saturn games (Columns Collection), quite some PSOne games (Tobal 2) and actually most of the PS2 games out there. While in theory 240p games don't have to be deinterlaced, 480i can be converted to 480p in a lot of different ways, providing different qualities in the result. 240p games run at 15khz as well and have still to be "upconverted" to 480p (31khz). Many newer TVs won't accept 240p on their component inputs. That's why it's often not an alternative to use a RGB Scart to Component (available for $50 to $100, e.g. from CYP) on those new TV sets.
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The FCC forbade TV stations from broadcasting in this format, and it is not supported by NTSC or PAL broadcast equipment.
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The trick used to achieve a progressive signal is to paint only even - or odd - lines instead of alternating between them. This is what causes the [[scanlines]] on a CRTs display; they are actually part of the image.  
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The 240p video mode is not considered by modern displays, since it is not part of the standard. Displays interpret it as 480i video, generating video artifacts and delay in the process.  
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==Processing==
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In order to display a 240p signal in a [[progressive]] display without the delay to process 480i signals and without the artifacts introduced by incorrect processing, a video processor can be used. One such example is the [[XRGB]], although there are many more [http://retrogaming.hazard-city.de/ options ].  
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There is also a [[240p test suite]] to evaluate how processors and TVs handle 240p video signals.
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==Support in modern consoles==
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More recent game systems tend to use only properly interlaced NTSC or PAL in addition to higher resolution modes, except when running games designed for older, compatible systems in their native resolutions. The [[PlayStation 2]] generates 240p/288p if a PlayStation game calls for this mode, as do many [[Virtual Console]] emulated games on [[Wii]]. Nintendo's official [[software development kit]] documentation refers to 240p as 'non-interlaced mode' or 'double-strike'.
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Shortly after the launch of the Wii Virtual Console service many users with [[component video]] cables experienced problems displaying some Virtual Console games due to certain TV models/manufacturers not supporting 240p over a component video connection. Nintendo's solution was to implement 'Wii Component Cable Interlace Mode' which forces the emulator to output 480i instead of 240p, however many games released prior have still not been updated.
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The PS3 does accept the official Playstation RGB cable, but outputs 480i through it, instead if 240p when needed.
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The Wii U does not output 240p though component.

Latest revision as of 16:55, 14 August 2015

In order to save costs and present a stable image on interlaced displays, most games developed before the year 2000 - and hence all the consoles and arcade games that played them - are rendered in a resolution around 320 pixels wide by 240 lines high, commonly referred as 240p. This video mode is actually a hack on top of the NTSC standard, but it works on all analogue displays.

The FCC forbade TV stations from broadcasting in this format, and it is not supported by NTSC or PAL broadcast equipment.

The trick used to achieve a progressive signal is to paint only even - or odd - lines instead of alternating between them. This is what causes the scanlines on a CRTs display; they are actually part of the image.

The 240p video mode is not considered by modern displays, since it is not part of the standard. Displays interpret it as 480i video, generating video artifacts and delay in the process.

Processing

In order to display a 240p signal in a progressive display without the delay to process 480i signals and without the artifacts introduced by incorrect processing, a video processor can be used. One such example is the XRGB, although there are many more options .

There is also a 240p test suite to evaluate how processors and TVs handle 240p video signals.

Support in modern consoles

More recent game systems tend to use only properly interlaced NTSC or PAL in addition to higher resolution modes, except when running games designed for older, compatible systems in their native resolutions. The PlayStation 2 generates 240p/288p if a PlayStation game calls for this mode, as do many Virtual Console emulated games on Wii. Nintendo's official software development kit documentation refers to 240p as 'non-interlaced mode' or 'double-strike'.

Shortly after the launch of the Wii Virtual Console service many users with component video cables experienced problems displaying some Virtual Console games due to certain TV models/manufacturers not supporting 240p over a component video connection. Nintendo's solution was to implement 'Wii Component Cable Interlace Mode' which forces the emulator to output 480i instead of 240p, however many games released prior have still not been updated.

The PS3 does accept the official Playstation RGB cable, but outputs 480i through it, instead if 240p when needed.

The Wii U does not output 240p though component.