Sec.  15.122   Closed caption decoder requirements for digital television receivers
and converter boxes.

   (a)(1) Effective July 1, 2002, all digital television receivers with picture
   screens in the 4:3 aspect ratio with picture screens measuring 13 inches or
   larger diagonally, all digital television receivers with picture screens in
   the 16:9 aspect ratio measuring 7.8 inches or larger vertically and all
   separately sold DTV tuners shipped in interstate commerce or manufactured in
   the United States shall comply with the provisions of this section.

   Note  to paragraph(a)(1): This paragraph places no restrictions on the
   shipping or sale of digital television receivers that were manufactured
   before July 1, 2002.

   (2)  Effective  July 1, 2002, DTV converter boxes that allow digitally
   transmitted television signals to be displayed on analog receivers shall
   pass available analog caption information to the attached receiver in a form
   recognizable by that receiver's built-in caption decoder circuitry.

   Note  to paragraph(a)(2): This paragraph places no restrictions on the
   shipping or sale of DTV converter boxes that were manufactured before July
   1, 2002.

   (b) Digital television receivers and tuners must be capable of decoding
   closed captioning information that is delivered pursuant to EIA–708–B:
   “Digital Television (DTV) Closed Captioning” (incorporated by reference, see
    Sec. 15.38).

   (c) Services. (1) Decoders must be capable of decoding and processing data
   for the six standard services, Caption Service #1 through Caption Service
   #6.

   (2) Decoders that rely on Program and System Information Protocol data to
   implement  closed captioning functions must be capable of decoding and
   processing the Caption Service Directory data. Such decoders must be capable
   of decoding all Caption Channel Block Headers consisting of Standard Service
   Headers, Extended Service Block Headers, and Null Block headers. However,
   decoding of the data is required only for Standard Service Blocks (Service
   IDs <-6), and then only if the characters for the corresponding language are
   supported. The decoders must be able to display the directory for services 1
   through 6.

   (d) Code space organization. (1) Decoders must support Code Space C0, G0,
   C1, and G1 in their entirety.
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   (2) The following characters within code space G2 must be supported:

   (i) Transparent space ([TSP]).

   (ii) Non-breaking transparent space ([NBTSP]).

   (iii) Solid block ( ).

   (iv) Trademark symbol (^TM ).

   (v) Latin-1 characters Š, Œ, š, œ, Ÿ.

   (3)  The substitutions in Table 2 are to be made if a decoder does not
   support the remaining G2 characters.

   Table 2—G2 Character Substitution Table
   G2 Character Substitute with
   Open single quote (‘), G2 char code 0×31 G0 single quote (`), char code 0×27
   Close single quote (’), G2 char code 0×32 G0 single quote ('), char code
   0×27
   Open double quote (“), G2 char code 0×33 G0 double quote (“), char code 0×22
   Close double quote (”), G2 char code 0×34 G0 double quote (”), char code
   0×22
   Bold bullet (•), G2 char code 0×35 G1 bullet (•), char code 0×B7
   Elipsis (. . .), G2 char code 0×25 G0 underscore (_), char code 0×5F
   One-eighth ( 1/8), G2 char code 0×76 G0 percent sign (%), char code 0×25
   Three-eighths ( 3/8), G2 char code 0×77 G0 percent sign (%), char code 0×25
   Five-eighths ( 5/8), G2 char code 0×78 G0 percent sign (%), char code 0×25
   Seven-eighths ( 7/8), G2 char code 0×79 G0 percent sign (%), char code 0×25
   Vertical border (|), G2 char code 0×7A G0 stroke (|), char code 0×7C
   Upper-right border (⌉), G2 char code 0×7B G0 dash (-), char code 0×2D
   Lower-left border (⌊), G2 char code 0×7C G0 dash (-), char code 0×2D
   Horizontal border (―), G2 char code 0×7D G0 dash (-), char code 0×2D
   Lower-right border (⌋), G2 char code 0×7E G0 dash (-), char code 0×2D
   Upper-left border (⌈), G2 char code 0×7F G0 dash (-), char code 0×2D

   (4) Support for code spaces C2, C3, and G3 is optional. All unsupported
   graphic symbols in the G3 code space are to be substituted with the G0
   underscore character (_), char code 0×5F.

   (e) Screen coordinates. Table 3 specifies the screen coordinate resolutions
   and limits for anchor point positioning in 4:3 and 16:9 display formats, and
   the number of characters per row.

   Table 3—Screen Coordinate Resolutions and Limits
   Screen aspect ratio Maximum anchor position resolution Minimum anchor
   position resolution Maximum displayed rows Maximum characters per row
   4:3 75v×160h 15v×32h 4 32
   16:9 75v×210h 15v×42h 4 42
   Other 75v×(5×H) 15v×H* 4 ^1

   ^1H = 32 × (the width of the screen in relation to a 4:3 display). For
   example, the 16:9 format is 1/3 wider than a 4:3 display; thus, H = 32 * 4/3
   = 42.667, or 42.

   (1) This means that the minimum grid resolution for a 4:3 aspect ratio
   instrument is 15 vertical positions × 32 horizontal positions. This minimum
   grid resolution for 16:9 ratio instrument is 15 vertical positions × 42
   horizontal positions. These minimum grid sizes are to cover the entire
   safe-title area of the corresponding screen.

   (2)  The  minimum  coordinates  equate to a1/5reduction in the maximum
   horizontal and vertical grid resolution coordinates. Caption providers are
   to use the maximum coordinate system values when specifying anchor point
   positions. Decoders using the minimum resolution are to divide the provided
   horizontal and vertical screen coordinates by 5 to derive the equivalent
   minimum coordinates.

   (3) Any caption targeted for both 4:3 and 16:9 instruments is limited to 32
   contiguous characters per row. If a caption is received by a 4:3 instrument
   that is targeted for a 16:9 display only, or requires a window width greater
   than 32 characters, then the caption may be completely disregarded by the
   decoder. 16:9 instruments should be able to process and display captions
   intended for 4:3 displays, providing all other minimum recommendations are
   met.

   (4) If the resulting size of any window is larger than the safe title area
   for the corresponding display's aspect ratio, then this window will be
   completely disregarded.

   (f) Caption windows. (1) Decoders need to display no more than 4 rows of
   captions  on the screen at any given time, regardless of the number of
   windows displayed. This implies that no more than 4 windows can be displayed
   at any given time (with each having only one caption row). However, decoders
   should maintain storage to support a minimum total of 8 rows of captions.
   This storage is needed for the worst-case support of a displayed window with
   4 rows of captioning and a non-displayed window which is buffering the
   incoming rows for the next 4-row caption. As implied above, the maximum
   number of windows that may be displayed at any one time by a minimum decoder
   implementation is 4. If more than 4 windows are defined in the caption
   stream, the decoder may disregard the youngest and lowest priority window
   definition(s). Caption providers must be aware of this limitation, and
   either restrict the total number of windows used or accept that some windows
   will not be displayed.

   (2) Decoders do not need to support overlapped windows. If a window overlaps
   another window, the overlapped window need not be displayed by the decoder.

   (3)  At a minimum, decoders will assume that all windows have rows and
   columns  “locked”. This implies that if a decoder implements the SMALL
   pen-size, then word-“un”wrapping, when shrinking captions, need not be
   implemented. Also, if a decoder implements the LARGE pen size, then word
   wrapping (when enlarging captions) need not be implemented.

   (4) Whenever possible, the receiver should render embedded carriage returns
   as line breaks, since these carriage returns indicate an important aspect of
   the caption's formatting as determined by the service provider. However, it
   may sometimes be necessary for the receiver to ignore embedded line breaks.
   For example, if a caption is to appear in a larger font, and if its window's
   rows and/or columns are unlocked, the rows of text may need to become longer
   or shorter to fit within the allocated space. Such automatic reformatting of
   a caption is known as “word wrap.” If decoders support word-wrapping, it
   must be implemented as follows:

   (i)  The  receiver  should  follow  standard typographic practice when
   implementing word wrap. Potential breaking points (word-wrapping points) are
   indicated by the space character (20h) and by the hyphen character (2Dh).

   (ii) If a row is to be broken at a space, the receiver should remove the
   space from the caption display. If a row is to be broken after a hyphen, the
   hyphen should be retained.

   (iii) If an embedded return is to be removed, it should usually be replaced
   with a space. However, if the character to the left of the embedded return
   is a hyphen, the embedded return should be removed but NOT replaced with a
   space.

   (iv) This specification does not include optional hyphens, nor does it
   provide for any form of automatic hyphenation. No non-breaking hyphen is
   defined.  The  non-breaking  space  (A0h  in  the G1 code set) and the
   non-breaking  transparent space (21h in the G2 code set) should not be
   considered as potential line breaks.

   (v) If a single word exceeds the length of a row, the word should be placed
   at  the start of a new row, broken at the character following the last
   character that fits on the row, and continued with further breaks if needed.

   (g)  Window  text  painting. (1) All decoders should implement “left”,
   “right”, and “center” caption-text justification. Implementation of “full”
   justification is optional. If “full” justification is not implemented, fully
   justified captions should be treated as though they are “left” justified.

   (i) For “left” justification, decoders should display any portion of a
   received  row  of text when it is received. For “center”, “right”, and
   “full” justification, decoders may display any portion of a received row of
   text when it is received, or may delay display of a received row of text
   until reception of a row completion indicator. A row completion indicator is
   defined as receipt of a CR, ETX or any other command, except SetPenColor,
   SetPenAttributes, or SetPenLocation where the pen relocation is within the
   same row.

   (ii) Receipt of a character for a displayed row which already contains text
   with “center”, “right” or “full” justification will cause the row to be
   cleared  prior  to the display of the newly received character and any
   subsequent characters. Receipt of a justification command which changes the
   last received justification for a given window will cause the window to be
   cleared.

   (2) At a minimum, decoders must support LEFT_TO_RIGHT printing.

   (3) At a minimum, decoders must support BOTTOM_TO_TOP scrolling. For windows
   sharing the same horizontal scan lines on the display, scrolling may be
   disabled.

   (4) At a minimum, decoders must support the same recommended practices for
   scroll rate as is provided for NTSC closed-captioning.

   (5) At a minimum, decoders must support the same recommended practices for
   smooth scrolling as is provided for NTSC closed-captioning.

   (6) At a minimum, decoders must implement the “snap” window display effect.
   If  the window “fade” and “wipe” effects are not implemented, then the
   decoder will “snap” all windows when they are to be displayed, and the
   “effect speed” parameter is ignored.

   (h)  Window  colors and borders. At a minimum, decoders must implement
   borderless windows with solid, black backgrounds (i.e., border type = NONE,
   fill color = (0,0,0), fill opacity = SOLID), and borderless transparent
   windows (i.e., border type = NONE, fill opacity = TRANSPARENT).

   (i) Predefined window and pen styles. Predefined Window Style and Pen Style
   ID's may be provided in the DefineWindow command. At a minimum, decoders
   should implement Predefined Window Attribute Style 1 and Predefined Pen
   Attribute Style 1, as shown in Table 4 and Table 5, respectively.

   Table 4—Predefined Window Style ID's
   Style ID # Justify Print direction Scroll
   direction Word wrap Display
   effect Effect
   direction Effect
   speed Fill color Fill opacity Border type Border color Usage
   1 Left Left-to-right Bottom-to-top No Snap n/a n/a (0,0,0) Black Solid None
   n/a NTSC Style PopUp Captions
   2 Left Left-to-right Bottom-to-top No Snap n/a n/a n/a Transparent None n/a
   PopUp Captions w/o Black Background
   3 Cntr Left-to-right Bottom-to-top No Snap n/a n/a (0,0,0) Black Solid None
   n/a NTSC Style Centered PopUp Captions
   4 Left Left-to-right Bottom-to-top Yes Snap n/a n/a (0,0,0) Black Solid None
   n/a NTSC Style RollUp Captions
   5 Left Left-to-right Bottom-to-top Yes Snap n/a n/a n/a Transparent None n/a
   RollUp Captions w/o Black Background
   6 Cntr Left-to-right Bottom-to-top Yes Snap n/a n/a (0,0,0) Black Solid None
   n/a NTSC Style Centered RollUp Captions
   7 Left Top-to-bottom Right-to-left No Snap n/a n/a (0,0,0) Black Solid None
   n/a Ticker Tape

   Table 5—Predefined Pen Style ID's
   Predefined style ID Pen size Font style Offset Italics Underline Edge type
   Foregrnd color Foregrnd opacity Backgrnd color Backgrnd opacity Edge color
   Usage
   1 Stndr 0 Normal No No None (2,2,2) White Solid (0,0,0) Black Solid n/a
   Default NTSC Style*
   2 Stndr 1 Normal No No None (2,2,2) Solid (0,0,0) White Solid n/a NTSC
   Style* Mono w/Serif
   3 Stndr 2 Normal No No None (2,2,2) White Solid (0,0,0) Black Solid n/a NTSC
   Style* Prop w/ Serif
   4 Stndr 3 Normal No No None (2,2,2) White Solid (0,0,0) Black Solid n/a NTSC
   Style* Mono w/o Serif
   5 Stndr 4 Normal No No None (2,2,2) White Solid (0,0,0) Black Solid n/a NTSC
   Style* Prop w/o Serif
   6 Stndr 3 Normal No No Unifrm (2,2,2) White Solid n/a Transparent (0,0,0)
   Black Mono w/o Serif, Bordered Text, No BG
   7 Stndr 4 Normal No No Unifrm (2,2,2) White Solid n/a Transparent (0,0,0)
   Black Prop. w/o Serif, Bordered Text, No BG

   *“NTSC Style”—White Text on Black Background

   (j) Pen size. (1) Decoders must support the standard, large, and small pen
   sizes and must allow the caption provider to choose a pen size and allow the
   viewer  to choose an alternative size. The STANDARD pen size should be
   implemented such that the height of the tallest character in any implemented
   font is no taller than1/15of the height of the safe-title area, and the
   width  of the widest character is no wider than1/32of the width of the
   safe-title area for 4:3 displays and1/42of the safe-title area width for
   16:9 displays.

   (2) The LARGE pen size should be implemented such that the width of the
   widest  character  in  any implemented font is no wider than1/32of the
   safe-title area for 16:9 displays. This recommendation allows for captions
   to grow to a LARGE pen size without having to reformat the caption since no
   caption will have more than 32 characters per row.

   (k) Font styles. (1) Decoders must support the eight fonts listed below.
   Caption providers may specify 1 of these 8 font styles to be used to write
   caption text. The styles specified in the “font style” parameter of the
   SetPenAttributes command are numbered from 0 through 7. The following is a
   list of the 8 required font styles. For information purposes only, each font
   style references one or more popular fonts which embody the characteristics
   of the style:

   (i) 0—Default (undefined)

   (ii) 1—Monospaced with serifs (similar to Courier)

   (iii) 2—Proportionally spaced with serifs (similar to Times New Roman)

   (iv) 3—Monospaced without serifs (similar to Helvetica Monospaced)

   (v) 4—Proportionally spaced without serifs (similar to Arial and Swiss)

   (vi) 5—Casual font type (similar to Dom and Impress)

   (vii) 6—Cursive font type (similar to Coronet and Marigold)

   (viii) 7—Small capitals (similar to Engravers Gothic)

   (2)  Font  styles may be implemented in any typeface which the decoder
   manufacturer deems to be a readable rendition of the font style, and need
   not be in the exact typefaces given in the example above. Decoders must
   include the ability for consumers to choose among the eight fonts. The
   decoder must display the font chosen by the caption provider unless the
   viewer chooses a different font.

   (l)  Character  offsetting.  Decoders need not implement the character
   offsetting ( i.e., subscript and superscript) pen attributes.

   (m) Pen styles. At a minimum, decoders must implement normal, italic, and
   underline pen styles.

   (n) Foreground color and opacity. (1) At a minimum, decoders must implement
   transparent, translucent, solid and flashing character foreground type
   attributes.

   (2) At a minimum, decoders must implement the following character foreground
   colors: white, black, red, green, blue, yellow, magenta and cyan.

   (3) Caption providers may specify the color/opacity. Decoders must include
   the ability for consumers to choose among the color/opacity options. The
   decoder must display the color/opacity chosen by the caption provider unless
   the viewer chooses otherwise.

   (o) Background color and opacity. (1) Decoders must implement the following
   background colors: white, black, red, green, blue, yellow, magenta and cyan.
   It is recommended that this background is extended beyond the character
   foreground to a degree that the foreground is separated from the underlying
   video by a sufficient number of background pixels to insure the foreground
   is separated from the background.

   (2) Decoders must implement transparent, translucent, solid and flashing
   background type attributes. Caption providers may specify the color/opacity.
   Decoders  must  include  the ability for consumers to choose among the
   color/opacity options. The decoder must display the color/opacity chosen by
   the caption provider unless the viewer chooses otherwise.

   (p) Character edges. Decoders must implement separate edge color and type
   attribute control.

   (q) Color representation. (1) At a minimum, decoders must support the 8
   colors listed in Table 6.

   Table 6—Minimum Color List Table
    Color  Red Green Blue
   Black     0     0    0
   White     2     2    2
   Red       2     0    0
   Green     0     2    0
   Blue      0     0    2
   Yellow    2     2    0
   Magenta   2     0    2
   Cyan      0     2    2

   (2)(i) When a decoder supporting this Minimum Color List receives an RGB
   value not in the list, it will map the received value to one of the values
   in the list via the following algorithm:

   (A) All one (1) values are to be changed to 0.

   (B) All two (2) values are to remain unchanged.

   (C) All three (3) values are to be changed to 2.

   (ii) For example, the RGB value (1,2,3) will be mapped to (0,2,2), (3,3,3)
   will be mapped to (2,2,2) and (1,1,1) will be mapped to (0,0,0).

   (3) Table 7 is an alternative minimum color list table supporting 22 colors.

   Table 7—Alternative Minimum Color List Table
       Color      Red Green Blue
   Black            0     0    0
   Gray             1     1    1
   White            2     2    2
   Bright White     3     3    3
   Dark Red         1     0    0
   Red              2     0    0
   Bright Red       3     0    0
   Dark Green       0     1    0
   Green            0     2    0
   Bright Green     0     3    0
   Dark Blue        0     0    1
   Blue             0     0    2
   Bright Blue      0     0    3
   Dark Yellow      1     1    0
   Yellow           2     2    0
   Bright Yellow    3     3    0
   Dark Magenta     1     0    1
   Magenta          2     0    2
   Bright Magenta   3     0    3
   Dark Cyan        0     1    1
   Cyan             0     2    2
   Bright Cyan      0     3    3

   (i) When a decoder supporting the Alternative Minimum Color List in Table 7
   receives an RGB value not in the list (i.e., an RGB value whose non-zero
   elements are not the same value), it will map the received value to one of
   the values in the list via the following algorithm:

   (A) For RGB values with all elements non-zero and different—e.g., (1,2,3),
   (3,2,1), and (2,1,3), the 1 value will be changed to 0, the 2 value will
   remain unchanged, and the 3 value will be changed to 2.

   (B)  For  RGB  values  with  all elements non-zero and with two common
   elements—e.g. (3,1,3), (2,1,2), and (2,2,3), if the common elements are 3
   and the uncommon one is 1, then the 1 elements is changed to 0; e.g. (3,1,3)
   → (3,0,3). If the common elements are 1 and the uncommon element is 3, then
   the 1 elements are changed to 0, and the 3 element is changed to 2; e.g.
   (1,3,1) → (0,2,0). In all other cases, the uncommon element is changed to
   the common value; e.g., (2,2,3) → (2,2,2), (1,2,1) → (1,1,1), and (3,2,3)
   → (3,3,3).

   (ii) All decoders not supporting either one of the two color lists described
   above, must support the full 64 possible RGB color value combinations.

   (r) Character rendition considerations. In NTSC Closed Captioning, decoders
   were required to insert leading and trailing spaces on each caption row.
   There were two reasons for this requirement:

   (1) To provide a buffer so that the first and last characters of a caption
   row do not fall outside the safe title area, and

   (2)  To provide a black border on each side of a character so that the
   “white” leading pixels of the first character on a row and the trailing
   “white”  pixels  of  the last character on a row do not bleed into the
   underlying video.

   (i) Since caption windows are required to reside in the safe title area of
   the DTV screen, reason 1 (above) is not applicable to DTVCC captions.

   (ii) The attributes available in the SetPenAttributes command for character
   rendition (e.g., character background and edge attributes) provide unlimited
   flexibility to the caption provider when describing caption text in an ideal
   decoder implementation. However, manufacturers need not implement all pen
   attributes.  Thus  it  is recommended that no matter what the level of
   implementation,  decoder  manufacturers  should  take into account the
   readability of all caption text against a variety of all video backgrounds,
   and  should  implement  some  automatic character delineation when the
   individual control of character foreground, background and edge is not
   supported.

   (s) Service synchronization. Service Input Buffers must be at least 128
   bytes in size. Caption providers must keep this lower limit in mind when
   following Delay commands with other commands and window text. In other
   words,  no  more  than  128 bytes of DTVCC commands and text should be
   transmitted  (encoded) before a pending Delay command's delay interval
   expires.

   (t) Settings. Decoders must include an option that permits a viewer to
   choose a setting that will display captions as intended by the caption
   provider (a default). Decoders must also include an option that allows a
   viewer's chosen settings to remain until the viewer chooses to alter these
   settings, including periods when the television is turned off.

   [ 65 FR 58471 , Sept. 29, 2000, as amended at  69 FR 2849 , Jan. 21, 2004]