Widescreen signaling

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

The signal is placed in line 23 (PAL) and lines 20/283 (PAL-M and NTSC) and has 14 bits of information indicating:

B00 to B03 - Aspect Ratio

B00	B01	B02	B03	Aspect ratio	Picture placement	Active lines
0	0	0	1	4:3	Full	576
1	0	0	0	14:9	Letterbox Centre	504
0	1	0	0	14:9	Letterbox Top	504
1	1	0	1	16:9	Letterbox Centre	430
0	0	1	0	16:9	Letterbox Top	430
1	0	1	1	>16:9	Letterbox deeper than 16:9
0	1	1	1	14:9	Full-height 4:3, framed to be "14:9-safe"	576
1	1	1	0	16:9	Full-height 16:9 (anamorphic)	576

B04 to B07 - Enhanced Services

B04	Mode
0	Camera Mode
1	Movie Mode

B05	Mode
0	PAL Standard
1	Colour Plus

B06	Mode
0	No Vertical Helper
1	Vertical Helper Present

B07	Ghost Cancellation

B08 to B10 - Subtitles

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

B11 to B13 - Others

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

References

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

See also

• PALPlus
• Active Format Description (AFD)
• Widescreen

External links

• PDF of WSS standard