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:
Read more about Widescreen Signaling: B00 To B03 - Aspect Ratio, B04 To B07 - Enhanced Services, B08 To B10 - Subtitles, B11 To B13 - Others