Goto Section: 17.118 | 17.120
FCC 17.119
Revised as of June 29, 2005
Goto Year:2004 |
2006
Sec. 15.119 Closed caption decoder requirements for analog television
receivers.
(a) Effective July 1, 1993, all TV broadcast receivers with picture
screens 33 cm (13 in) or larger in diameter shipped in interstate
commerce, manufactured, assembled, or imported from any foreign
country into the United States shall comply with the provisions of
this section.
Note: This paragraph places no restriction on the shipping or sale of
television receivers that were manufactured before July 1, 1993.
(b) Transmission format. Closed-caption information is transmitted on
line 21 of field 1 of the vertical blanking interval of television
signals, in accordance with Sec. 73.682(a)(22) of this chapter.
(c) Operating modes. The television receiver will employ
customer-selectable modes of operation for TV and Caption. A third
mode of operation, Text, may be included on an optional basis. The
Caption and Text Modes may contain data in either of two operating
channels, referred to in this document as C1 and C2. The television
receiver must decode both C1 and C2 captioning, and must display the
captioning for whichever channel the user selects. The TV Mode of
operation allows the video to be viewed in its original form. The
Caption and Text Modes define one or more areas (called "boxes") on
the screen within which caption or text characters are displayed.
Note: For more information regarding Text mode, see "Television
Captioning for the Deaf: Signal and Display Specifications",
Engineering Report No. E-7709-C, Public Broadcasting Service, dated
May 1980, and "TeleCaption II Decoder Module Performance
Specification", National Captioning Institute, Inc., dated November
1985. These documents are available, respectively, from the Public
Broadcasting Service, 1320 Braddock Place, Alexandria, VA 22314 and
from the National Captioning Institute, Inc., 5203 Leesburg Pike,
Falls Church, VA 22041.
(d) Screen format. The display area for captioning and text shall fall
approximately within the safe caption area as defined in paragraph
(n)(12) of this section. This display area will be further divided
into 15 character rows of equal height and 32 columns of equal width,
to provide accurate placement of text on the screen. Vertically, the
display area begins on line 43 and is 195 lines high, ending on line
237 on an interlaced display. All captioning and text shall fall
within these established columns and rows. The characters must be
displayed clearly separated from the video over which they are placed.
In addition, the user must have the capability to select a black
background over which the captioned letters are displaced.
(1) Caption mode. In the Caption Mode, text can appear on up to 4 rows
simultaneously anywhere on the screen within the defined display area.
In addition, a solid space equal to one column width may be placed
before the first character and after the last character of each row to
enhance legibility. The caption area will be transparent anywhere that
either:
(i) No standard space character or other character has been addressed
and no accompanying solid space is needed; or,
(ii) An accompanying solid space is used and a "transparent space"
special character has been addressed which does not immediately
precede or follow a displayed character.
(2) [Reserved]
(e) Presentation format. In analyzing the presentation of characters,
it is convenient to think in terms of a non-visible cursor which marks
the screen position at which the next event in a given mode and data
channel will occur. The receiver remembers the cursor position for
each mode even when data are received for a different address in an
alternate mode or data channel.
(1) Screen addressing. Two kinds of control codes are used to move the
cursor to specific screen locations. In Caption Mode, these addressing
codes will affect both row and column positioning. In Text Mode, the
codes affect only column positioning. In both modes, the addressing
codes are optional. Default positions are defined for each mode and
style when no addressing code is provided.
(i) The first type of addressing code is the Preamble Address Code
(PAC). It assigns a row number and one of eight "indent" figures. Each
successive indent moves the cursor four columns to the right (starting
from the left margin). Thus, an indent of 0 places the cursor at
Column 1, an indent of 4 sets it at Column 5, etc. The PAC indent is
non-destructive to displayable characters. It will not affect the
display to the left of the new cursor position on the indicated row.
Note that Preamble Address Codes also set initial attributes for the
displayable characters which follow. See paragraph (h) of this section
and the Preamble Address Code table.
(ii) The second type of addressing code is the Tab Offset, which is
one of three Miscellaneous Control Codes. Tab Offset will move the
cursor one, two, or three columns to the right. The character cells
skipped over will be unaffected; displayable characters in these
cells, if any, will remain intact while empty cells will remain empty,
in the same manner that a PAC indent is non-destructive.
(2) [Reserved]
(f) Caption Mode. There are three styles of presenting text in Caption
Mode: roll-up, pop-on, and paint-on. Character display varies
significantly with the style used, but certain rules of character
erasure are common to all styles. A character can be erased by
addressing another character to the same screen location or by
backspacing over the character from a subsequent location on the same
row. The entire displayed memory will be erased instantly by receipt
of an Erase Displayed Memory command. Both displayed memory and
non-displayed memory will be entirely erased simultaneously by either:
The user switching receiver channels or data channels (C1/C2) or
fields (F1/F2) in decoders so equipped; the loss of valid data (see
paragraph (j) of this section); or selecting non-captioning receiver
functions which use the display memory of the decoder. Receipt of an
End of Caption command will cause a displayed caption to become
non-displayed (and vice versa) without being erased from memory.
Changing the receiver to a non-captioning mode which does not require
use of the decoder's display memory will leave that memory intact, and
the decoder will continue to process data as if the caption display
were selected.
(1) Roll-up. Roll-up style captioning is initiated by receipt of one
of three Miscellaneous Control Codes that determine the maximum number
of rows displayed simultaneously, either 2, 3 or 4 contiguous rows.
These are the three Roll-Up Caption commands.
(i) The bottom row of the display is known as the "base row". The
cursor always remains on the base row. Rows of text roll upwards into
the contiguous rows immediately above the base row to create a
"window" 2 to 4 rows high.
(ii) The Roll-Up command, in normal practice, will be followed (not
necessarily immediately) by a Preamble Address Code indicating the
base row and the horizontal indent position. If no Preamble Address
Code is received, the base row will default to Row 15 or, if a roll-up
caption is currently displayed, to the same base row last received,
and the cursor will be placed at Column 1. If the Preamble Address
Code received contains a different base row than that of a currently
displayed caption, the entire window will move intact (and without
erasing) to the new base row immediately.
(iii) Each time a Carriage Return is received, the text in the top row
of the window is erased from memory and from the display or scrolled
off the top of the window. The remaining rows of text are each rolled
up into the next highest row in the window, leaving the base row blank
and ready to accept new text. This roll-up must appear smooth to the
user, and must take no more than 0.433 second to complete. The cursor
is automatically placed at Column 1 (pending receipt of a Preamble
Address Code).
(iv) Increasing or decreasing the number of roll-up rows instantly
changes the size of the active display window, appropriately turning
on or off the display of the top one or two rows. A row which is
turned off should also be erased from memory.
(v) Characters are always displayed immediately when received by the
receiver. Once the cursor reaches the 32nd column position on any row,
all subsequent characters received prior to a Carriage Return,
Preamble Address Code, or Backspace will be displayed in that column
replacing any previous character occupying that address.
(vi) The cursor moves automatically one column to the right after each
character or Mid-Row Code received. A Backspace will move the cursor
one column to the left, erasing the character or Mid-Row Code
occupying that location. (A Backspace received when the cursor is in
Column 1 will be ignored.)
(vii) The Delete to End of Row command will erase from memory any
characters or control codes starting at the current cursor location
and in all columns to its right on the same row. If no displayable
characters remain on the row after the Delete to End of Row is acted
upon, the solid space (if any) for that row should also be erased to
conform with the following provisions.
(viii) If a solid space is used for legibility, it should appear when
the first displayable character (not a transparent space) or Mid-Row
Code is received on a row, not when the Preamble Address Code, if any,
is given. A row on which there are no displayable characters or
Mid-Row Codes will not display a solid space, even when rolled up
between two rows which do display a solid space.
(ix) If the reception of data for a row is interrupted by data for the
alternate data channel or for Text Mode, the display of caption text
will resume from the same cursor position if a Roll-Up Caption command
is received and no Preamble Address Code is given which would move the
cursor.
(x) A roll-up caption remains displayed until one of the standard
caption erasure techniques is applied. Receipt of a Resume Caption
Loading command (for pop-on style) or a Resume Direct Captioning
command (for paint-on style) will not affect a roll-up display.
Receipt of a Roll-Up Caption command will cause any pop-on or paint-on
caption to be erased from displayed memory and non-displayed memory.
(2) Pop-on. Pop-on style captioning is initiated by receipt of a
Resume Caption Loading command. Subsequent data are loaded into a
non-displayed memory and held there until an End of Caption command is
received, at which point the non-displayed memory becomes the
displayed memory and vice versa. (This process is often referred to as
"flipping memories" and does not automatically erase memory.) An End
of Caption command forces the receiver into pop-on style if no Resume
Caption Loading command has been received which would do so. The
display will be capable of 4 full rows, not necessarily contiguous,
simultaneous anywhere on the screen.
(i) Preamble Address Codes can be used to move the cursor around the
screen in random order to place captions on Rows 1 to 15. Carriage
Returns have no effect on cursor location during caption loading.
(ii) The cursor moves automatically one column to the right after each
character or Mid-Row Code received. Receipt of a Backspace will move
the cursor one column to the left, erasing the character or Mid-Row
Code occupying that location. (A Backspace received when the cursor is
in Column 1 will be ignored.) Once the cursor reaches the 32nd column
position on any row, all subsequent characters received prior to a
Backspace, an End of Caption, or a Preamble Address Code, will replace
any previous character at that location.
(iii) The Delete to End of Row command will erase from memory any
characters or control codes starting at the current cursor location
and in all columns to its right on the same row. If no displayable
characters remain on a row after the Delete to End of Row is acted
upon, the solid space (if any) for that element should also be erased.
(iv) If data reception is interrupted during caption loading by data
for the alternate caption channel or for Text Mode, caption loading
will resume at the same cursor position if a Resume Caption Loading
command is received and no Preamble Address Code is given that would
move the cursor.
(v) Characters remain in non-displayed memory until an End of Caption
command flips memories. The caption will be erased without being
displayed upon receipt of an Erase Non-Displayed Memory command, a
Roll-Up Caption command, or if the user switches receiver channels,
data channels or fields, or upon the loss of valid data (see paragraph
(j) of this section).
(vi) A pop-on caption, once displayed, remains displayed until one of
the standard caption erasure techniques is applied or until a Roll-Up
Caption command is received. Characters within a displayed pop-on
caption will be replaced by receipt of the Resume Direct Captioning
command and paint-on style techniques (see below).
(3) Paint-on. Paint-on style captioning is initiated by receipt of a
Resume Direct Captioning command. Subsequent data are addressed
immediately to displayed memory without need for an End of Caption
command.
(i) Preamble Address Codes can be used to move the cursor around the
screen in random order to display captions on Rows 1 to 15. Carriage
Returns have no affect on cursor location during direct captioning.
The cursor moves automatically one column to the right after each
character or Mid-Row Code is received. Receipt of a Backspace will
move the cursor one column to the left, erasing the character or
Mid-Row Code occupying that location. (A Backspace received when the
cursor is in Column 1 will be ignored.) Once the cursor reaches the
32nd column position on any row, all subsequent characters received
prior to a Preamble Address Code or Backspace will be displayed in
that column replacing any previous character occupying that location.
(ii) The Delete to End of Row command will erase from memory any
characters or control codes starting at the current cursor location
and in all columns to its right on the same row. If no displayable
characters remain on the row after the Delete to End of Row is acted
upon, the solid space (if any) for that element should also be erased.
(iii) If the reception of data is interrupted during the direct
captioning by data for the alternate caption channel or for Text Mode,
the display of caption text will resume at the same cursor position if
a Resume Direct Captioning command is received and no Preamble Address
Code is given which would move the cursor.
(iv) Characters remain displayed until one of the standard caption
erasure techniques is applied or until a Roll-Up Caption command is
received. An End of Caption command leaves a paint-on caption fully
intact in non-displayed memory. In other words, a paint-on style
caption behaves precisely like a pop-on style caption which has been
displayed.
(g) Character format. Characters are to be displayed on the screen
within a character "cell" which is the height and width of a single
row and column. The following codes define the displayable character
set. Television receivers manufactured prior to January 1, 1996 and
having a character resolution of 5×7 dots, or less, may display the
allowable alternate characters in the character table. A statement
must be in a prominent location on the box or other package in which
the receiver is to be marketed, and information must be in the owner's
manual, indicating the receiver displays closed captioning in upper
case only.
Character Set Table
Special Characters
These require two bytes for each symbol. Each hex code as shown will
be preceded by a 11h for data channel 1 or by a 19h for data channel
2. For example: 19h 37h will place a musical note in data channel 2.
------------------------------------------------------------------------
HEX Example Alternate Description
------------------------------------------------------------------------
30 ® See note\1\ Registered mark symbol
31 ° ............ Degree sign
32 \1/2\ ............ \1/2\
33 ¿ ............ Inverse query
34 TM See note\1\ Trademark symbol
35 ¢ ............ Cents sign
36 £ ............ Pounds Sterling sign
37 [sung] ............ Music note
38 à A Lower-case a with grave accent
39 ............ Transparent space
3A è E Lower-case e with grave accent
3B â A Lower-case a with circumflex
3C ê E Lower-case e with circumflex
3D î I Lower-case i with circumflex
3E ô O Lower-case o with circumflex
3F û U Lower-case u with circumflex
------------------------------------------------------------------------
\1\ Note: The registered and trademark symbols are used to satisfy
certain legal requirements. There are various legal ways in which
these symbols may be drawn or displayed. For example, the trademark
symbol may be drawn with the ``T'' next to the ``M'' or over the
``M''. It is preferred that the trademark symbol be superscripted,
i.e., XYZTM. It is left to each individual manufacturer to interpret
these symbols in any way that meets the legal needs of the user.
Standard characters
------------------------------------------------------------------------
HEX Example Alternate Description
------------------------------------------------------------------------
20 .......... Standard space
21 ! .......... Exclamation mark
22 `` .......... Quotation mark
23 # .......... Pounds (number) sign
24 $ .......... Dollar sign
25 % .......... Percentage sign
26 & .......... Ampersand
27 ' .......... Apostrophe
28 ( .......... Open parentheses
29 ) .......... Close parentheses
2A á A Lower-case a with acute accent
2B + .......... Plus sign
2C , .......... Comma
2D - .......... Minus (hyphen) sign
2E . .......... Period
2F / .......... Slash
30 0 .......... Zero
31 1 .......... One
32 2 .......... Two
33 3 .......... Three
34 4 .......... Four
35 5 .......... Five
36 6 .......... Six
37 7 .......... Seven
38 8 .......... Eight
39 9 .......... Nine
3A : .......... Colon
3B ; .......... Semi-colon
3C < .......... Less than sign
3D = .......... Equal sign
3E > .......... Greater than sign
3F ? .......... Question mark
40 @ .......... At sign
41 A .......... Upper-case A
42 B .......... Upper-case B
43 C .......... Upper-case C
44 D .......... Upper-case D
45 E .......... Upper-case E
46 F .......... Upper-case F
47 G .......... Upper-case G
48 H .......... Upper-case H
49 I .......... Upper-case I
4A J .......... Upper-case J
4B K .......... Upper-case K
4C L .......... Upper-case L
4D M .......... Upper-case M
4E N .......... Upper-case N
4F O .......... Upper-case O
50 P .......... Upper-case P
51 Q .......... Upper-case Q
52 R .......... Upper-case R
53 S .......... Upper-case S
54 T .......... Upper-case T
55 U .......... Upper-case U
56 V .......... Upper-case V
57 W .......... Upper-case W
58 X .......... Upper-case X
59 Y .......... Upper-case Y
5A Z .......... Upper-case Z
5B [ .......... Open bracket
5C é E Lower-case e with acute accent
5D ] .......... Close bracket
5E í I Lower-case i with acute accent
5F ó O Lower-case o with acute accent
60 ú U Lower-case u with acute accent
61 a A Lower-case a
62 b B Lower-case b
63 c C Lower-case c
64 d D Lower-case d
65 e E Lower-case e
66 f F Lower-case f
67 g G Lower-case g
68 h H Lower-case h
69 i I Lower-case i
6A j J Lower-case j
6B k K Lower-case k
6C l L Lower-case l
6D m M Lower-case m
6E n N Lower-case n
6F o O Lower-case o
70 p P Lower-case p
71 q Q Lower-case q
72 r R Lower-case r
73 s S Lower-case s
74 t T Lower-case t
75 u U Lower-case u
76 v V Lower-case v
77 w W Lower-case w
78 x X Lower-case x
79 y Y Lower-case y
7A z Z Lower-case z
7B ç C Lower-case c with cedilla
7C ÷ .......... Division sign
7D Ñ .......... Upper-case N with tilde
7E ñ Ñ Lower-case n with tilde
7F [squf] .......... Solid block
------------------------------------------------------------------------
(h) Character Attributes--(1) Transmission of Attributes. A character
may be transmitted with any or all of four attributes: Color, italics,
underline, and flash. All of these attributes are set by control codes
included in the received data. An attribute will remain in effect
until changed by another control code or until the end of the row is
reached. Each row begins with a control code which sets the color and
underline attributes. (White non-underlined is the default display
attribute if no Preamble Address Code is received before the first
character on an empty row.) Attributes are not affected by transparent
spaces within a row.
(i) All Mid-Row Codes and the Flash On command are spacing attributes
which appear in the display just as if a standard space (20h) had been
received. Preamble Address Codes are non-spacing and will not alter
any attributes when used to position the cursor in the midst of a row
of characters.
(ii) The color attribute has the highest priority and can only be
changed by the Mid-Row Code of another color. Italics has the next
highest priority. If characters with both color and italics are
desired, the italics Mid-Row Code must follow the color assignment.
Any color Mid-Row Code will turn off italics. If the least significant
bit of a Preamble Address Code or of a color or italics Mid-Row Code
is a 1 (high), underlining is turned on. If that bit is a 0 (low),
underlining is off.
(iii) The flash attribute is transmitted as a Miscellaneous Control
Code. The Flash On command will not alter the status of the color,
italics, or underline attributes. However, any color or italics
Mid-Row Code will turn off flash.
(iv) Thus, for example, if a red, italicized, underlined, flashing
character is desired, the attributes must be received in the following
order: a red Mid-Row or Preamble Address Code, an italics Mid-Row Code
with underline bit, and the Flash On command. The character will then
be preceded by three spaces (two if red was assigned via a Preamble
Address Code).
(2) Display of attributes. The underline attribute will be displayed
by drawing a line beneath the character in the same color as the
character. The flash attribute will be displayed by causing the
character to blink from the display at least once per second. The
italic attribute must be capable of being displayed by either a
special italic font, or by the modification of the standard font by
slanting. The user may be given the option to select other methods of
italic display as well. The support of the color attributes is
optional. If the color attributes are supported, they will be
displayed in the color they have been assigned. If color attributes
are not supported, the display may be in color, but all color changes
will be ignored.
(i) Control codes. There are three different types of control codes
used to identify the format, location, attributes, and display of
characters: Preamble Address Codes, Mid-Row Codes, and Miscellaneous
Control Codes.
(1) Each control code consists of a pair of bytes which are always
transmitted together in a single field of line 21 and which are
normally transmitted twice in succession to help insure correct
reception of the control instructions. The first of the control code
bytes is a non-printing character in the range 10h to 1Fh. The second
byte is always a printing character in the range 20h to 7Fh. Any such
control code pair received which has not been assigned a function is
ignored. If the non-printing character in the pair is in the range 00h
to 0Fh, that character alone will be ignored and the second character
will be treated normally.
(2) If the second byte of a control code pair does not contain odd
parity (see paragraph (j) of this section), then the pair is ignored.
The redundant transmission of the pair will be the instruction upon
which the receiver acts.
(3) If the first byte of the first transmission of a control code pair
fails the parity check, then that byte is inserted into the currently
active memory as a solid block character (7Fh) followed by whatever
the second byte is. Again, the redundant transmission of the pair will
be the controlling instruction.
(4) If the first transmission of a control code pair passes parity, it
is acted upon within one video frame. If the next frame contains a
perfect repeat of the same pair, the redundant code is ignored. If,
however, the next frame contains a different but also valid control
code pair, this pair, too, will be acted upon (and the receiver will
expect a repeat of this second pair in the next frame). If the first
byte of the expected redundant control code pair fails the parity
check and the second byte is identical to the second byte in the
immediately preceding pair, then the expected redundant code is
ignored. If there are printing characters in place of the redundant
code, they will be processed normally.
(5) There is provision for decoding a second data channel. The second
data channel is encoded with the same control codes and procedures
already described. The first byte of every control code pair indicates
the data channel (C1/C2) to which the command applies. Control codes
which do not match the data channel selected by the user, and all
subsequent data related to that control code, are ignored by the
receiver.
Mid-Row Codes
------------------------------------------------------------------------
Data Data
channel channel Attribute description
1 2
------------------------------------------------------------------------
11 20 19 20 White.
11 21 19 21 White Underline.
11 22 19 22 Green.
11 23 19 23 Green Underline.
11 24 19 24 Blue.
11 25 19 25 Blue Underline.
11 26 19 26 Cyan.
11 27 19 27 Cyan Underline.
11 28 19 28 Red.
11 29 19 29 Red Underline.
11 2A 19 2A Yellow.
11 2B 19 2B Yellow Underline.
11 2C 19 2C Magenta.
11 2D 19 2D Magenta Underline.
11 2E 19 2E Italics.
11 2F 19 2F Italics Underline.
------------------------------------------------------------------------
Miscellaneous Control Codes
------------------------------------------------------------------------
Data Data
channel channel Mne- monic Command description
1 2
------------------------------------------------------------------------
14 20 1C 20 RCL................. Resume caption loading.
14 21 1C 21 BS.................. Backspace.
14 22 1C 22 AOF................. Reserved (formerly Alarm Off).
14 23 1C 23 AON................. Reserved (formerly Alarm On).
14 24 1C 24 DER................. Delete to End of Row.
14 25 1C 25 RU2................. Roll-Up Captions-2 Rows.
14 26 1C 26 RU3................. Roll-Up Captions-3 Rows.
14 27 1C 27 RU4................. Roll-Up Captions-4 Rows.
14 28 1C 28 FON................. Flash On.
14 29 1C 29 RDC................. Resume Direct Captioning.
14 2A 1C 2A TR.................. Text Restart.
14 2B 1C 2B RTD................. Resume Text Display.
14 2C 1C 2C EDM................. Erase Displayed Memory.
14 2D 1C 2D CR.................. Carriage Return.
14 2E 1C 2E ENM................. Erase Non-Displayed Memory.
14 2F 1C 2F EOC................. End of Caption (Flip
Memories).
17 21 1F 21 TO1................. Tab Offset 1 Column.
17 22 1F 22 TO2................. Tab Offset 2 Columns.
17 23 1F 23 TO3................. Tab Offset 3 Columns.
------------------------------------------------------------------------
Preamble Address Codes
-------------------------------------------------------------------------------
---------------------------------
Row Row Row Row Row Row Row Row
Row Row Row Row Row Row Row
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15
-------------------------------------------------------------------------------
---------------------------------
First byte of code pair:
Data Channel 1................... 11 11 12 12 15 15 16 16
17 17 10 13 13 14 14
Data Channel 2................... 19 19 1A 1A 1D 1D 1E 1E
1F 1F 18 1B 1B 1C 1C
Second byte of code pair:
White............................ 40 60 40 60 40 60 40 60
40 60 40 40 60 40 60
White Underline.................. 41 61 41 61 41 61 41 61
41 61 41 41 61 41 61
Green............................ 42 62 42 62 42 62 42 62
42 62 42 42 62 42 62
Green Underline.................. 43 63 43 63 43 63 43 63
43 63 43 43 63 43 63
Blue............................. 44 64 44 64 44 64 44 64
44 64 44 44 64 44 64
Blue Underline................... 45 65 45 65 45 65 45 65
45 65 45 45 65 45 65
Cyan............................. 46 66 46 66 46 66 46 66
46 66 46 46 66 46 66
Cyan Underline................... 47 67 47 67 47 67 47 67
47 67 47 47 67 47 67
Red.............................. 48 68 48 68 48 68 48 68
48 68 48 48 68 48 68
Red Underline.................... 49 69 49 69 49 69 49 69
49 69 49 49 69 49 69
Yellow........................... 4A 6A 4A 6A 4A 6A 4A 6A
4A 6A 4A 4A 6A 4A 6A
Yellow Underline................. 4B 6B 4B 6B 4B 6B 4B 6B
4B 6B 4B 4B 68 4B 6B
Magenta.......................... 4C 6C 4C 6C 4C 6C 4C 6C
4C 6C 4C 4C 6C 4C 6C
Magenta Underline................ 4D 6D 4D 6D 4D 6D 4D 6D
4D 6D 4D 4D 6D 4D 6D
White Italics.................... 4E 6E 4E 6E 4E 6E 4E 6E
4E 6E 4E 4E 6E 4E 6E
White Italics Underline.......... 4F 6F 4F 6F 4F 6F 4F 6F
4F 6F 4F 4F 6F 4F 6F
Indent 0......................... 50 70 50 70 50 70 50 70
50 70 50 50 70 50 70
Indent 0 Underline............... 51 71 51 71 51 71 51 71
51 71 51 51 71 51 71
Indent 4......................... 52 72 52 72 52 72 52 72
52 72 52 52 72 52 72
Indent 4 Underline............... 53 73 53 73 53 73 53 73
53 73 53 53 73 53 73
Indent 8......................... 54 74 54 74 54 74 54 74
54 74 54 54 74 54 74
Indent 8 Underline............... 55 75 55 75 55 75 55 75
55 75 55 55 75 55 75
Indent 12........................ 56 76 56 76 56 76 56 76
56 76 56 56 76 56 76
Indent 12 Underline.............. 57 77 57 77 57 77 57 77
57 77 57 57 77 57 77
Indent 16........................ 58 78 58 78 58 78 58 78
58 78 58 58 78 58 78
Indent 16 Underline.............. 59 79 59 79 59 79 59 79
59 79 59 59 79 59 79
Indent 20........................ 5A 7A 5A 7A 5A 7A 5A 7A
5A 7A 5A 5A 7A 5A 7A
Indent 20 Underline.............. 5B 7B 5B 7B 5B 7B 5B 7B
5B 7B 5B 5B 7B 5B 7B
Indent 24........................ 5C 7C 5C 7C 5C 7C 5C 7C
5C 7C 5C 5C 7C 5C 7C
Indent 24 Underline.............. 5D 7D 5D 7D 5D 7D 5D 7D
5D 7D 5D 5D 7D 5D 7D
Indent 28........................ 5E 7E 5E 7E 5E 7E 5E 7E
5E 7E 5E 5E 7E 5E 7E
Indent 28 Underline.............. 5F 7F 5F 7F 5F 7F 5F 7F
5F 7F 5F 5F 7F 5F 7F
-------------------------------------------------------------------------------
---------------------------------
Note: All indent codes (second byte equals 50h-5fh, 70th-7fh) assign white as t
he color attribute.
(j) Data rejection. The receiver should provide an effective procedure
to verify data. A receiver will reject data if the data is invalid, or
if the data is directed to the data channel or field not selected by
the user. Invalid data is any data that fails to pass a check for odd
parity, or which, having passed the parity check, is assigned no
function.
(1) If a print character fails to pass a check for parity, a solid
block (7Fh) should be displayed in place of the failed character. In
addition, valid data can be corrupted in many ways and may not be
suitable for display. For example, repeated fields, skipped fields and
altered field sequences are all possible from consumer video equipment
and might present meaningless captions.
(2) The receiver will ignore data rejected due to being directed to a
deselected field or channel. However, this will not cause the display
to be disabled.
(k) Automatic display enable/disable. The receiver shall provide an
automatic enable/disable capability to prevent the display of invalid
or incomplete data, when the user selects the Caption Mode. The
display should automatically become enable after the receiver verifies
the data as described in paragraph (j) of this section. The display
will be automatically disabled when there is a sustained detection of
invalid data. The display will be re-enabled when the data
verification process has been satisfied once again.
(l) Compatibility with Cable Security Systems. Certain cable
television security techniques, such as signal encryption and copy
protection, can alter the television signal so that some methods of
finding line 21 will not work. In particular, counting of lines or
timing from the start of the vertical blanking interval may cause
problems. Caption decoding circuitry must function properly when
receiving signals from cable security systems that were designed and
marketed prior to April 5, 1991. Further information concerning such
systems is available from the National Cable Television Association,
Inc., Washington, DC, and from the Electronic Industries Association,
Washington, DC.
(m) Labelling and consumer information requirements. The box or other
package in which the individual television receiver is to be marketed
shall carry a statement in a prominent location, visible to the buyer
before purchase, which reads as follows:
This television receiver provides display of television closed
captioning in accordance with Sec. 15.119 of the FCC rules.
Receivers that do not support color attributes or text mode, as well
as receivers that display only upper-case characters pursuant to
paragraph (g) of this section, must include with the statement, and in
the owner's manual, language indicating that those features are not
supported.
(n) Glossary of terms. The following terms are used to describe
caption decoder specifications:
(1) Base row: The bottom row of a roll-up display. The cursor always
remains on the base row. Rows of text roll upwards into the contiguous
rows immediately above the base row.
(2) Box: The area surrounding the active character display. In Text
Mode, the box is the entire screen area defined for display, whether
or not displayable characters appear. In Caption Mode, the box is
dynamically redefined by each caption and each element of displayable
characters within a caption. The box (or boxes, in the case of a
multiple-element caption) includes all the cells of the displayed
characters, the non-transparent spaces between them, and one cell at
the beginning and end of each row within a caption element in those
decoders that use a solid space to improve legibility.
(3) Caption window: The invisible rectangle which defines the top and
bottom limits of a roll-up caption. The window can be 2 to 4 rows
high. The lowest row of the window is called the base row.
(4) Cell: The discrete screen area in which each displayable character
or space may appear. A cell is one row high and one column wide.
(5) Column: One of 32 vertical divisions of the screen, each of equal
width, extending approximately across the full width of the safe
caption area as defined in paragraph (n)(12) of this section. Two
additional columns, one at the left of the screen and one at the
right, may be defined for the appearance of a box in those decoders
which use a solid space to improve legibility, but no displayable
characters may appear in those additional columns. For reference,
columns may be numbered 0 to 33, with columns 1 to 32 reserved for
displayable characters.
(6) Displayable character: Any letter, number or symbol which is
defined for on-screen display, plus the 20h space.
(7) Display disable: To turn off the display of captions or text (and
accompanying background) at the receiver, rather than through codes
transmitted on line 21 which unconditionally erase the display. The
receiver may disable the display because the user selects an alternate
mode, e.g., TV Mode, or because no valid line 21 data is present.
(8) Display enable: To allow the display of captions or text when they
are transmitted on line 21 and received as valid data. For display to
be enabled, the user must have selected Caption Mode or Text Mode, and
valid data for the selected mode must be present on line 21.
(9) Element: In a pop-on or paint-on style caption, each contiguous
area of cells containing displayable characters and non-transparent
spaces between those characters. A single caption may have multiple
elements. An element is not necessarily a perfect rectangle, but may
include rows of differing widths.
(10) Erase Display: In Caption Mode, to clear the screen of all
characters (and accompanying background) in response to codes
transmitted on line 21. (The caption service provider can accomplish
the erasure either by sending an Erase Displayed Memory command or by
sending an Erase Non-Displayed Memory command followed by an End of
Caption command, effectively making a blank caption "appear".) Display
can also be erased by the receiver when the caption memory erasure
conditions are met, such as the user changing TV channels.
(11) Row: One of 15 horizontal divisions of the screen, extending
across the full height of the safe caption area as defined in
paragraph (n)(12) of this section.
(12) Safe caption area: The area of the television picture within
which captioning and text shall be displayed to ensure visibility of
the information on the majority of home television receivers. The safe
caption area is specified as shown in the following figure:
[ec03jn91.009.gif]
View or download PDF
The dimensions of the above figure shall be as follows:
------------------------------------------------------------------------
Percent of
television
Label Dimensions picture
height
------------------------------------------------------------------------
A Television picture height....... 100.0
B Television picture width........ 133.33
C Height of safe caption area..... 80.0
D Width of safe caption area...... 106.67
E Vertical position of safe 10.0
caption area.
F Horizontal position of safe 13.33
caption area.
------------------------------------------------------------------------
(13) Special characters: Displayable characters (except for
"transparent space") which require a two-byte sequence of one
non-printing and one printing character. The non-printing byte varies
depending on the data channel. Regular characters require unique
one-byte codes which are the same in either data channel.
(14) Text: When written with an upper-case "T", refers to the Text
Mode. When written with a lower-case "t", refers to any combination of
displayable characters.
(15) Transparent space: Transmitted as a special character, it is a
one-column-wide space behind which program video is always visible
(except when a transparent space immediately precedes or follows a
displayable character and solid box is needed to make that character
legible).
[ 56 FR 27201 , June 13, 1991, as amended at 57 FR 19094 , May 4, 1992;
58 FR 44893 , Aug. 25, 1993]
Goto Section: 17.118 | 17.120
Goto Year: 2004 |
2006
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