Widescreen signaling

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In television technology, widescreen signaling (WSS) is a digital stream embedded in the analog TV signal describing qualities of the broadcast, in particular the intended aspect ratio of the image. This can be used by a widescreen TV or other device to switch to the correct display mode.

PAL and SECAM[edit]

For 625 scan line systems (PAL and SECAM), the signal is placed in line 23. It begins with a run-in code and start code followed by 14 bits of information.[1]

Group 1 (aspect ratio)[edit]

b00 b01 b02 b03 Aspect ratio Picture placement Active lines
0 0 0 0 - - -
0 0 0 1 4:3 Full 576
0 0 1 0 16:9 Letterbox top 432
0 0 1 1 - - -
0 1 0 0 14:9 Letterbox top 504
0 1 0 1 - - -
0 1 1 0 - - -
0 1 1 1 14:9 Full-height 4:3, framed to be "14:9-safe" 576
1 0 0 0 14:9 Letterbox centre 504
1 0 0 1 - - -
1 0 1 0 - - -
1 0 1 1 >16:9 Letterbox deeper than 16:9 <432
1 1 0 0 - - -
1 1 0 1 16:9 Letterbox centre 432
1 1 1 0 16:9 Full-height 16:9 (anamorphic) 576
1 1 1 1 - - -

Group 2 (enhanced services)[edit]

b04 Mode
0 Camera Mode (interlaced)
1 Movie Mode (progressive scan)
b05 Mode
0 PAL Standard
1 Colour Plus
b06 Mode
0 No Vertical helper
1 Vertical helper present

The above settings are related to PALplus.

b07 Ghost cancellation

Group 3 (subtitles)[edit]

b08 Mode
0 no subtitles
1 Teletext subtitles
b09 b10 Mode
0 0 No subtitles
1 0 Subtitles inside active image
0 1 Subtitles outside active image
1 1 Reserved

Group 4 (other)[edit]

b11 Mode
0 No surround sound information
1 Surround sound mode
b12 Mode
0 No copyright asserted or status unknown
1 Copyright asserted
b13 Mode
0 Copying not restricted
1 Copying restricted

NTSC[edit]

525 line systems made a provision using pulses for signalling wide screen and some other parameters in a similar manner to PAL and SECAM. Players output them and NTSC compatible TVs (including multiformat) recognise them.

See also[edit]

References[edit]

  • ETSI EN 300 294 "Television Systems: 625-Line Television Wide Screen Signaling (WSS)"

External links[edit]