Digital Television (DTV) Closed Captioning: 3D Extensions
|Publication Date:||1 October 2012|
1 Scope This standard specifies signaling to allow CTA-708  caption services to be rendered with stereoscopic 3D program content. CTA-708.1 defines the syntax and semantics of the SetDepth command. SetDepth is a variable-length command1 delivered in the C3 code set2 as defined in CTA-708 .
The principle of stereoscopic 3D TV involves displaying different views of a scene to the left and right eyes. The difference in horizontal position of a given object between the right- and left-eye views is called the disparity. Negative values of disparity cause the object to be perceived in front of the plane of the screen. Positive values of disparity cause the object to be perceived behind the plane of the screen. Zero disparity causes the object to appear at the plane of the screen.
This standard specifies a standardized method for associating a disparity value, or a series of disparity values that change over time, with a given caption window within a given caption service. Disparity values are specified using a horizontal resolution of 1920 units. For HDTV signals delivered at a resolution of 1920 pixels horizontally, one unit of disparity corresponds to one pixel. For HDTV signals delivered at a resolution of 1280 pixels horizontally, one unit of disparity corresponds to 1920/1280 or 1.5 pixels.
Notation for binary and hexadecimal numbers and bitstream syntax notation follows the same conventions as are used in CTA-708 .
2 Code space organization is defined in CEA-708  Sec. 7.1