PALplus

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PALplus was a broadcast standard compatible with PAL for analog color television . New features are included

  • the suppression of color artifacts at the transmitter ,
  • Ghosting suppression (optional)
  • a 16: 9 mode that contains more information than a normal 16: 9 film that is broadcast in PAL format (with the black stripes on top and bottom), as well
  • smaller auxiliary signals, e.g. B. Notes for the recipient,

When analog television broadcasting in PAL was switched off, PALplus also expired and is no longer used today.

16: 9 mode

In the 16: 9 mode, the 576 lines of the picture are used for picture information, which increases the sharpness in the vertical direction. The video bandwidth , ie the image sharpness in the horizontal direction, does not change for historical reasons: it remains at 5 MHz , which corresponds to approx. 560 pixels. If the bandwidth of the video signal were to be increased, the consequence would be that the video and audio signals would interfere with one another, ie the audio signal would be visible as a striped pattern and sharp edges would be audible as a rattle.

The improvement of the display boils down to two effects:

  • The lines are written more densely, in 16: 9 mode, like an anamorphic DVD, 576 lines are written at 9 ⁄ 16 instead of 12 ⁄ 16 of the picture height. This reduces banding and artifacts.
  • The vertical resolution for almost horizontal structures is increased by 33%. The vertical color resolution, which is significantly lower with PAL than with NTSC , and the horizontal resolution, which is already worse than the vertical resolution in normal PAL images, are not improved.

On the transmitter side, the 16: 9 picture is scaled down from 576 to 432 lines so that it can be displayed without distortion on a 4: 3 television set with a conventional PAL decoder . Such a television does not benefit from the increased image sharpness. The remaining lines in the upper and lower image area are kept at black level. The U color subcarrier - this is the color difference signal for blue in the YUV color model - of these lines is converted to receive an analog difference signal , which enables the full 576 lines for the brightness component to be restored. The color information for the image lines is not transmitted. This is expressed on normal PAL receivers in the typical faint dark blue and sometimes faint yellow streaks in the black upper and lower image areas. The blue color difference carrier U was chosen because the human eye is the least sensitive to blue and so the image artifacts are minimized on conventional 4: 3 receivers. The color information for these additionally inserted 144 image lines is not transmitted, but is obtained from the adjacent lines in the receiver by interpolation.

For the correct display of a PALplus picture, either a PALplus television or a normal 16: 9 television with an upstream, external PALplus decoder is required.

distribution

In Germany , some of the public television broadcasters used the standard frequently; They largely ignored the free-to-air private broadcasters. The pay TV broadcaster Premiere often broadcast its analogue programs in PALplus. With the decreasing importance of analog television reception in Germany and the expiry of EU funding, however, even the public broadcasters recently stopped purchasing new PALplus-compatible devices and replaced them with inexpensive, non-PALplus-compatible devices in the event of a defect.

The public television in Austria , ORF , distributed 16: 9 material in both national television programs for a number of years in analog form also in PALplus. After the feed to the broadcasting stations was switched to digital technology, the broadcast was back in PAL until the final switch to DVB-T .

In Switzerland , the German-language television station SF stopped broadcasting PALplus programs in mid-May 2005.

In Belgium , the Flemish public broadcaster VRT has a guideline according to which the majority of its self-produced programs are to be broadcast in PALplus. For example, the daily news is broadcast in PALplus, as are most of the weekly shows. Newer films are also broadcast in PALplus. The commercial television station VTM also broadcasts in PALplus, although not as often as VRT. At this station, too, the news is broadcast in PALplus, as are special shows and films. In Wallonia , the public broadcaster RTBF broadcasts purchased 16: 9 programs in PALplus, e.g. B. Films, but he prefers to produce his own programs in 4: 3 format. Wallonia's commercial TV station RTL TVI rarely broadcasts in PALplus and stays with the older 4: 3 format.

In the Netherlands , broadcasts in PALplus were rare. Sometimes special shows and series were also broadcast in PALplus. 16: 9 programs that were bought by other broadcasters were rarely converted to 4: 3, but instead broadcast in their original aspect ratio in PALplus.

In Portugal , the private broadcaster TVI broadcast films in PALplus from 1994 onwards. Later, only the public broadcaster RTP broadcast selected programs in this standard.

history

At the end of the 1980s, a European high-definition television standard was propagated in competition with the Japanese MUSE standard (1125 lines), HD-MAC with 1250 lines (see also HDTV ), i.e. twice the number of lines of PAL, and an aspect ratio of 16: 9. As an interim solution, D2-MAC compatible with HD-MAC was introduced, also in 16: 9 format, but only with the number of PAL lines. The permanent introduction of these analog TV standards (with digital multi-channel sound) has failed on the market because the digital HD format 1080i60 with MPEG-2 compression was already being developed in the USA. The successor PALplus was not able to assert itself decisively either.

criticism

The decoding of the 16: 9 mode requires the intermediate storage of the complete picture. At the time of the intended introduction, this was time-consuming. As a result, few high-priced TVs support this mode. PALplus television sets advertised as such were only available on the market for a short time. Nowadays (partial) PALplus capability is hidden behind performance features such as “automatic 16: 9/4: 3 changeover”.

See also

Web links

Individual evidence

  1. ↑ Better television - tips and tricks for widescreen television 16: 9 ( Memento of the original from November 17, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. PDF brochure of the NDR, accessed on July 12, 2010 @1@ 2Template: Webachiv / IABot / www1.ndr.de