Widescreen signaling

From Wikipedia, the free encyclopedia
Jump to: navigation, search

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 or other device to switch to the correct display mode.

PAL and SECAM Systems[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.

Group 1 (Aspect Ratio)[edit]

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 432
0 0 1 0 16:9 Letterbox top 432
1 0 1 1 >16:9 Letterbox deeper than 16:9 <432
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

Group 2 (Enhanced Services)[edit]

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

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 Systems[edit]

525 scan line systems (PAL-M and NTSC) put the WSS data in lines 20 and 283. A start code consisting of the bits "10" is used, followed by 14 bits of information.

Word 0[edit]

b0 Aspect Ratio
0 4:3
1 16:9
b1 Mode
0 Normal
1 Letterbox

b2-b5 all have the value "0".

Word 1[edit]

b6-b9 are reserved and all have the value "0".

Word 2[edit]

b10-b13 are reserved and all have the value "0".

See also[edit]

References[edit]

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

External links[edit]