EIA-608

Open main menu Wikipedia Search EditWatch this page EIA-608 Page issues EIA-608, also known as "line 21 captions" and "CEA-608",[1] used to be the standard for closed captioning for NTSC TV broadcasts in the United States, Canada and Mexico. It also specifies an "Extended Data Service", which is a means for including a VCR control service with a now/next EPG for NTSC transmissions that operates on the even line 21 field, similar to the TeleText based VPS that operates on line 16 which is used in PAL countries.

It was developed by the Electronic Industries Alliance and required by law to be implemented in most television receivers made in the United States.

EIA-608 captions are transmitted on either the odd or even fields of line 21 with an odd parity bit in the non-visible active video data area in NTSC broadcasts, and are also sometimes present in the picture user data in ATSC transmissions. It uses a fixed bandwidth of 480 bit/s per line 21 field for a maximum of 32 characters per line per caption (maximum four captions) for a 30 frame broadcast. The odd field captions relate to the primary audio track and the even field captions related to the SAP or secondary audio track which is generally a second language translation of the primary audio, such as a French or Spanish translation of an English-speaking TV show.

Raw EIA-608 caption byte pairs are becoming less prevalent as digital television replaces analog. ATSC broadcasts instead use the EIA-708 caption protocol to encapsulate both the EIA-608 caption pairs as well as a native EIA-708 stream. EIA-608 has had revisions with the addition of extended character sets to fully support the representation of the Spanish, French, German languages, and cross section of other Western European languages. EIA-608 was also extended to support two byte characters for the Korean and Japanese markets. The full version of EIA-708 has support for more character sets and better caption positioning options; however, because of existing EIA-608 hardware and revisions to the format, there has been little or no real world use of the format besides simple 608 to 708 inline conversions.

Channels

DVD GOP User Data Insertion

DVB Transport Insertion

SDI/MXF SMPTE 291M Insertion

Extended Data Service

Characters

Non-Western Norpak Character Sets

Control commands

References

External links

Last edited 24 days ago by an anonymous user RELATED ARTICLES Closed captioning CEA-708 Teletext television information retrieval service developed in the United Kingdom in the early 1970s Wikipedia

Content is available under CC BY-SA 3.0 unless otherwise noted. Terms of UsePrivacyDesktop Close Editing EIA-608 Next

EIA-608, also known as "line 21 captions" and "CEA-608",^[1] used to be the standard for closed captioning for NTSC TV broadcasts in the United States, Canada and Mexico. It also specifies an "Extended Data Service", which is a means for including a VCR control service with a now/next EPG for NTSC transmissions that operates on the even line 21 field, similar to the TeleText based VPS that operates on line 16 which is used in PAL countries.

It was developed by the Electronic Industries Alliance and required by law to be implemented in most television receivers made in the United States.

Channels

EIA-608 defines four channels of caption information, so that a program could, for example, have captions in four different languages. There are two channels, called 1 and 2 by the standard, in each of the two fields of a frame. However, the channels are often presented to users numbered simply as CC1-2 for the odd field and CC3-4 for the even field. However due to bandwidth limitations on either field, CC1 and CC3 are the only ones used, meaning that there has been little use for the second channel. Early Spanish SAP captioned broadcasts first used the second channel CC2 because the original caption decoders only read the first odd field, but later switched to using CC3 for bandwidth reasons. Due to the same bandwidth reasons XDS was never used by Spanish-speaking stations.

Within each channel, there are two streams of information which might be considered sub-channels: one carries "captions" and the other "text." The latter is not in common use due to the lack of hardware support and bandwidth available. Text is signaled by the use of text commands and can be used for a formatted URL string with a 16-bit checksum that designates a web site that the captions relate to or a local station communication channel.

This layering is based on the OSI Protocol Reference Model:

CC Layers	OSI Layers	DVB/MXF Layers	Comments
	Application	Interpretation	Issuing commands and appending text to rows
	Presentation	Coding	Breaking up individual commands and characters
	Session	Channel	Channel Byte Stream
	--	Selection	CC channel assembly from CC byte pairs
Injection	Transport	Synchronization	CC byte pairs extracted/synchronized with/from video frames
	Network	unused	directly connected link
	Link	SMPTE 259M or H.222 or MXF	video frames or VBI data split from link format
SDI or DVD	Physical	ODFM or storage medium	link format demodulated/retrieved from transmission/source

DVD GOP User Data Insertion

The user data structure that follows a H.262 GOP header is as follows (the same would apply after an ISO/IEC 14496-2 GOP header):

Length	Name	Type	Default
32 bits	user_data_start_code	patterned bslbf	0x000001B2
16 bits	user_identifier	ASCII bslbf	CC
8 bits	user_data_type_code	uimsbf	1
8 bits	caption_block_size	inverted uimsbf	0xf8
1 bit	caption_odd_field_first	flag	1
1 bit	caption_filler	alignment	0
5 bits	caption_block_count	uimsbf	15
1 bit	caption_extra_field_added	flag	0
X*24 bits	caption_block	binary	free form

bslbf: bit string, left bit first ; uimsbf: unsigned integer, most significant bit first

Caption blocks are inserted after the sequence and GOP headers, so each block is for one second of video which would end up being one or two long lines or three to four short lines of text. Also that means if the caption_block_count is greater than 30 then the block contains both interleaved caption fields and one could devise the framing rate from the caption_block_count. However since the data is grouped together the framing rate will almost always be 30/1.001, unlike the ATSC method that inserts one byte pair for each field after the picture header making framing rates of 24/1.001 possible for HD content. Since when a decoder does a 3:2 pull-down for NTSC output the captions will remain in sync.

DVD Caption Block
Length	Name	Type	Default
7 bits	caption_filler	alignment	0x7f
1 bit	caption_odd_field	uimsbf	1 or 0
8 bits	caption_first_byte	odd parity uimsbf	0x80
8 bits	caption_second_byte	odd parity uimsbf	0x80

DVB Transport Insertion

The packet-ed structure that is inserted before the H.222 video packet is as follows for a frame of associated video:

Length	Name	Type	Default
32 bits	private_stream_1_start_code	patterned bslbf	0x000001BD
16 bits	PES_packet_length	uimsbf	176
2 bits	PES_version	uimsbf	2
1 bit	PES_priority	flag	0
2 bits	PES_scrambling_control	uimsbf	0
1 bit	data_alignment_indicator	flag	1
2 bits	copyright original	uimsbf	0
2 bits	PTS_DTS_flag	uimsbf	2
6 bits	various_PES_flags	uimsbf	0
8 bits	PES_header_data_length	uimsbf	36
40 bits	PTS	uimsbf	varies
248 bits	stuffing_bytes	uimsbf	255
8 bits	data_identifier	uimsbf	153
8 bits	data_unit_id	uimsbf	197
8 bits	data_unit_length	uimsbf	3
2 bits	reserved_future_use	uimsbf	3
1 bit	field_parity (CC1/2)	flag	0
5 bits	line_offset	uimsbf	21
16 bits	closed_captioning_data_block	uimsbf	608 caption
8 bits	data_unit_id	uimsbf	197
8 bits	data_unit_length	uimsbf	3
2 bits	reserved_future_use	uimsbf	3
1 bit	field_parity (CC3/4/XDS)	flag	1
5 bits	line_offset	uimsbf	21
16 bits	closed_captioning_data_block	uimsbf	608 caption
8 bits	data_unit_id	uimsbf	255
8 bits	data_unit_length	uimsbf	124
124*8 bits	stuffing_bytes	uimsbf	255

bslbf: bit string, left bit first ; uimsbf: unsigned integer, most significant bit first

This structure was designed for any digital VBI data and was optimized to carry three or more 43-byte Teletext packets. e.g. a page header and two associated lines. For Teletext subtitles, the data_unit_id is set to 3. In this form, captions have to be separated into byte pairs spread over frames in one second of video rather than grouped into one block as with the DVD structure. The same is true for Teletext subtitles with more than one line of text.

SDI/MXF SMPTE 291M Insertion

The packet-ed structure that is inserted before the SMPTE 259M active video frame or MXF essence video packet is coded as follows for a frame of associated video:

Length	Name	Type	Default
16 or 128 bits	ancillary_flag or ancillary_header	patterned bslbf or 7 uimsbf	0xFFFF or varies
8 bits	data_id	uimsbf	97
8 bits	secondary_data_id	uimsbf	2
8 bits	data_count	uimsbf	varies
X*24 bits	caption_data_block	binary	free form

bslbf: bit string, left bit first ; uimsbf: unsigned integer, most significant bit first

This structure was designed for any digital audio or metadata that is to be synchronized with a video frame. SDI transports every eight bits in a 10 bit aligned packet, unlike MXF which is byte aligned and the ancillary flag bytes are replaced by 128 bit header.

SDI/MXF Caption Block
Length	Name	Type	Default
1 bit	caption_odd_field (CC1/2 = 1; CC3/4 = 0)	flag	1
2 bits	caption_reserved	uimsbf	0
5 bits	caption_line_offset	uimsbf	15
8 bits	caption_first_byte	odd parity uimsbf	0x80
8 bits	caption_second_byte	odd parity uimsbf	0x80

Extended Data Service

The EIA-608 data stream format includes Extended Data Service (XDS), a variety of information about the transmission. It is all optional,:

program name
offensiveness rating (violence, sex, etc.)
program category (drama, game show, etc.)

Characters

There are three sets of characters that the EIA-608 stream can direct the receiver to display: basic characters, special characters, and extended characters. A single two-byte EIA-608 command (represented by a single VBI line) can specify two basic characters, one special character, or one extended character.

Extended characters are a later addition to the standard and their decoding is optional.

EIA-608 provides controls for the color of the foreground and background of the text, underlining, blinking, and italics. The default color scheme is white characters on a black background, all opaque.

The Transparent Space special character implies a transparent background even in the absence of any background control commands. As the foreground of this character is a blank space, it really means a gap in the close caption text.

Non-Caption Data

This is used to either pad out the field line when no captions are sent or for the eXtended Data Service.

          +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+              +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 null pad |P|0|0|0|0|0|0|0| |P|0|0|0|0|0|0|0| XDS metadata |P|0|0|0| CLASS | |P|0|0|0|  TYPE | 
          +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+              +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
          15             8   7             0               15             8   7             0

Basic North American character set

A command with bits 13 or 14 on directs the receiver to display two basic characters at the current cursor position for the current mode (closed caption or text). Each character is a code point (identifies the character to display), as follows.

                       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
  modified 7-bit ASCII |P|  CHARACTER1 | |P|  CHARACTER2 |
                       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
                       15             8   7             0

The code is almost identical to ASCII; the exceptions are shown in red.

Binary	Decimal	Hex	Glyph
0010 0000	32	20	(SP)
0010 0001	33	21	!
0010 0010	34	22	"
0010 0011	35	23	#
0010 0100	36	24	$
0010 0101	37	25	%
0010 0110	38	26	&
0010 0111	39	27	’
0010 1000	40	28	(
0010 1001	41	29	)
0010 1010	42	2A	á
0010 1011	43	2B	+
0010 1100	44	2C	,
0010 1101	45	2D	-
0010 1110	46	2E	.
0010 1111	47	2F	/
0011 0000	48	30	0
0011 0001	49	31	1
0011 0010	50	32	2
0011 0011	51	33	3
0011 0100	52	34	4
0011 0101	53	35	5
0011 0110	54	36	6
0011 0111	55	37	7
0011 1000	56	38	8
0011 1001	57	39	9
0011 1010	58	3A	:
0011 1011	59	3B	;
0011 1100	60	3C	<
0011 1101	61	3D	=
0011 1110	62	3E	>
0011 1111	63	3F	?

Binary	Decimal	Hex	Glyph
0100 0000	64	40	@
0100 0001	65	41	A
0100 0010	66	42	B
0100 0011	67	43	C
0100 0100	68	44	D
0100 0101	69	45	E
0100 0110	70	46	F
0100 0111	71	47	G
0100 1000	72	48	H
0100 1001	73	49	I
0100 1010	74	4A	J
0100 1011	75	4B	K
0100 1100	76	4C	L
0100 1101	77	4D	M
0100 1110	78	4E	N
0100 1111	79	4F	O
0101 0000	80	50	P
0101 0001	81	51	Q
0101 0010	82	52	R
0101 0011	83	53	S
0101 0100	84	54	T
0101 0101	85	55	U
0101 0110	86	56	V
0101 0111	87	57	W
0101 1000	88	58	X
0101 1001	89	59	Y
0101 1010	90	5A	Z
0101 1011	91	5B	[
0101 1100	92	5C	é
0101 1101	93	5D	]
0101 1110	94	5E	í
0101 1111	95	5F	ó

Binary	Decimal	Hex	Glyph
0110 0000	96	60	ú
0110 0001	97	61	a
0110 0010	98	62	b
0110 0011	99	63	c
0110 0100	100	64	d
0110 0101	101	65	e
0110 0110	102	66	f
0110 0111	103	67	g
0110 1000	104	68	h
0110 1001	105	69	i
0110 1010	106	6A	j
0110 1011	107	6B	k
0110 1100	108	6C	l
0110 1101	109	6D	m
0110 1110	110	6E	n
0110 1111	111	6F	o
0111 0000	112	70	p
0111 0001	113	71	q
0111 0010	114	72	r
0111 0011	115	73	s
0111 0100	116	74	t
0111 0101	117	75	u
0111 0110	118	76	v
0111 0111	119	77	w
0111 1000	120	78	x
0111 1001	121	79	y
0111 1010	122	7A	z
0111 1011	123	7B	ç
0111 1100	124	7C	÷
0111 1101	125	7D	Ñ
0111 1110	126	7E	ñ
0111 1111	127	7F	SB

In the table above, SB represents a solid block. The apostrophe (code 27), which may originally have been intended to be a neutral apostrophe as in ASCII, is now recommended to be rendered as a right single quotation mark (Unicode U+2019). For a neutral single quote/apostrophe, the plain single quote from the extended character set should be used.^[2]

Special North American character set

The only real use in North America of this set is the use of the Eighth note character to denote changes from spoken dialogue to singing or musical only scenes.

It is an acceptable broadcast engineering practice when translating EIA-608 to Teletext for PAL compatible countries to substitute this character for a number sign because of its similarity to a sharp.

A command to display a special character has a first byte of 0x11 or 0x19 (depending upon channel). The second byte is a code point in the range 0x30-0x3F as follows.

 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 |P|0|0|1|C|0|0|1| |P|0|1|1|  CHAR |
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 15             8   7             0
 P = odd parity ; C = second channel toggle

Binary	Decimal	Hex	Glyph
0011 0000	48	30	®
0011 0001	49	31	°
0011 0010	50	32	½
0011 0011	51	33	¿
0011 0100	52	34	™
0011 0101	53	35	¢
0011 0110	54	36	£
0011 0111	55	37	♪
0011 1000	56	38	à
0011 1001	57	39	TS
0011 1010	58	3A	è
0011 1011	59	3B	â
0011 1100	60	3C	ê
0011 1101	61	3D	î
0011 1110	62	3E	ô
0011 1111	63	3F	û

TM is short for unregistered trademark and should be represented in superscript (™). TS in the table above represents a "transparent space" or non-breaking space. Finally, the Eighth note (♪) is used to denote singing or background music in captions.

Extended Western European character set

 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 |P|0|0|1|C|0|1|S| |P|0|1|CHARACTER|
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 15             8   7             0
 P = odd parity ; C = second channel toggle ; S = char set toggle

These extended character sets are rarely used due to most European countries using the BBC Ceefax based Teletext system.

The Ceefax system is more prone to character errors due to the greater number of data bits (337 versus 16) encoded per VBI field, these errors occur either on noise prone analog transmissions or connections.

A command to display an extended Spanish/French or miscellaneous character has a first byte of 0x12 or 0x1A (depending upon channel).
A command to display an extended Portuguese/German/Danish character has a first byte of 0x13 or 0x1B (depending upon channel).

The second byte is a code point in the range 0x20-0x3F is as follows

Extended Spanish/Miscellaneous
Binary	Decimal	Hex	Glyph
0010 0000	32	20	Á
0010 0001	33	21	É
0010 0010	34	22	Ó
0010 0011	35	23	Ú
0010 0100	36	24	Ü
0010 0101	37	25	ü
0010 0110	38	26	´
0010 0111	39	27	¡
0010 1000	40	28	*
0010 1001	41	29	'
0010 1010	42	2A	-
0010 1011	43	2B	©
0010 1100	44	2C	SM
0010 1101	45	2D	·
0010 1110	46	2E	"
0010 1111	47	2F	"

Extended French
Binary	Decimal	Hex	Glyph
0011 0000	48	30	À
0011 0001	49	31	Â
0011 0010	50	32	Ç
0011 0011	51	33	È
0011 0100	52	34	Ê
0011 0101	53	35	Ë
0011 0110	54	36	ë
0011 0111	55	37	Î
0011 1000	56	38	Ï
0011 1001	57	39	ï
0011 1010	58	3A	Ô
0011 1011	59	3B	Ù
0011 1100	60	3C	ù
0011 1101	61	3D	Û
0011 1110	62	3E	«
0011 1111	63	3F	»

Portuguese
Binary	Decimal	Hex	Glyph
0010 0000	32	20	Ã
0010 0001	33	21	ã
0010 0010	34	22	Í
0010 0011	35	23	Ì
0010 0100	36	24	ì
0010 0101	37	25	Ò
0010 0110	38	26	ò
0010 0111	39	27	Õ
0010 1000	40	28	õ
0010 1001	41	29	{
0010 1010	42	2A	}
0010 1011	43	2B	\
0010 1100	44	2C	^
0010 1101	45	2D	_
0010 1110	46	2E	\|
0010 1111	47	2F	~

German/Danish
Binary	Decimal	Hex	Glyph
0011 0000	48	30	Ä
0011 0001	49	31	ä
0011 0010	50	32	Ö
0011 0011	51	33	ö
0011 0100	52	34	ß
0011 0101	53	35	¥
0011 0110	54	36	¤
0011 0111	55	37	¦
0011 1000	56	38	Å
0011 1001	57	39	å
0011 1010	58	3A	Ø
0011 1011	59	3B	ø
0011 1100	60	3C	+
0011 1101	61	3D	+
0011 1110	62	3E	+
0011 1111	63	3F	+

SM is short for service mark and should be represented in superscript. The single quote mark is a curly left and double quote marks are curly left and right. The plus signs refer to top left, top right, lower left and lower right corners for box drawing.

Non-Western Norpak Character Sets

When used all standard and extended character sets are unused in favor of the following predefined sets, care must be taken to not emulate any control commands. This is an extension submitted to the CEC by Norpak who made a similar extension to the Teletext format for the Chinese market. The main use has been to provide double byte code point captioning to the Japanese, Taiwanese and South Korean markets. A command to switch character sets has a first byte of 0x17 or 0x1F (depending upon channel). The second byte is a character set reference in the range 0x24-0x2A as follows

 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 |P|0|0|1|C|1|1|1| |P|0|1|0|CHARSET|
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 15             8   7             0

Binary	Decimal	Hex	Set in Use
0010 0100	36	24	Standard
0010 0101	37	25	Standard Double Height
0010 0110	38	26	Decoder Specific 1
0010 0111	39	27	Decoder Specific 2
0010 1000	40	28	China's GB 2312 (1980)
0010 1001	41	29	Korea's KS C 5601 (1987)
0010 1010	42	2A	Loadable

Control commands

Bits 15 and 7 are always odd parity bits. Bit 11 is always the channel bit.

Preamble address code with masking bit 15,11 and 7 as already defined above can be interpreted from following table

bits	interpretation
14-13	always 0
12	always 1
10-8	row position indicator
6	always 1
5	row position indicator
4-1	text attribute indicator
0	underline indicator

Row Preamble Standard Address and Style
(Default Row 11 = 0,top rows 1-4 = 1-2,bottom rows 12-13 = 3)
                +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+                  +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 preamble style |P|0|0|1|C|0|ROW| |P|1|N|0|STYLE|U| preamble address |P|0|0|1|C|0|ROW| |P|1|N|1|CURSR|U|
                +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+                  +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
                15             8   7             0                   15             8   7             0
Row Preamble Extended Address and Style
(Bottom Rows 14-15 = 0,middle rows = 5-10 = 1-3)
                +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+                  +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 preamble style |P|0|0|1|C|1|ROW| |P|1|N|0|STYLE|U| preamble address |P|0|0|1|C|1|ROW| |P|1|N|1|CURSR|U|
                +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+                  +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
                15             8   7             0                   15             8   7             0
 P = odd parity ; C = second channel toggle
 U = underline toggle ; N = next row down toggle
 (if style or cursor position not set,
  defaults are regular white text with black background
  at cursor = 0, cursor - multiple of 4)
 text style enumerations:
  {white=0,green,blue,cyan,red,yellow,magenta,italic white}

The row bits specify which of the fifteen screen rows should contain the caption text: row 11 (0000), 1 (0010), 2 (0011), 3, 4, 12, 13, 14, 15, 5, 6, 7, 8, 9, or 10 (1111).

The attributes bits allow 16 possibilities, which are: white (0000), green, blue, cyan, red, yellow, magenta, italics, indent 0, indent 4, indent 8, indent 12, indent 16, indent 20, indent 24, indent 28 (1111).

For a midrow code these are as follows: Bits 14, 13, 10, 9, 6 and 4 are always 0, bits 12, 8 and 5 are always 1. Bits 3, 2 and 1 form the color attribute 0001X10X(see the listing of attributes). Bit 0 indicates underline.

Mid Row Style Change
(style remains in effect until either next change or end of row signaled by a control or preamble)
           +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+              +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
  bg color |P|0|0|1|C|0|0|0| |P|0|1|0|COLOR|T| midrow style |P|0|0|1|C|0|0|1| |P|0|1|0|STYLE|U|
           +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+              +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
           15             8   7             0               15             8   7             0
       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+            +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 no bg |P|0|0|1|C|1|1|1| |P|0|1|0|1|1|0|1| black text |P|0|0|1|C|1|1|1| |P|0|1|0|1|1|1|U|
       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+            +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
       15             8   7             0             15             8   7             0
 P = odd parity ; C = second channel toggle
 T = partially transparent ; U = underline toggle
 bg color enumerations:
 {white=0,green,blue,cyan,red,yellow,magenta,black}

For other control codes these are as follows: Bits 14, 13, 9, 6 and 4 are always 0, bits 12, 10 and 5 are always 1. Bit 8 chooses between line 21 and 284. Bits 3, 2, 1 and 0 identify the particular action.

The command bits allow 16 possibilities, which are: resume caption loading (0000), backspace (0001), delete to end of row (0100), roll-up captions 2-rows, roll-up captions 3 rows, roll-up captions 4-rows, flash on (0.25 seconds once per second), resume direct captioning, text restart, resume text display, erase displayed memory, carriage return, erase nondisplayed memory, end of caption (1111).

For tabs these are as follows: Bits 14, 13, 6, 4, 3, 2 are always 0, bits 12, 10, 9, 8, 5 are always 1. Bits 1 and 0 determine the number of tab offsets.

Considering parity bit already ignored hex value have of 2 byte data is following command:

cc_data 0 (hex)	cc_data 0 (binary)	cc_data 1 (hex)	cc_data 1 (binary)	Command
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x20	00100000	resume caption loading (start buffered caption text)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x21	00100001	backspace (overwrite last char)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x22	00100010	alarm off (unused)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x23	00100011	alarm on (unused)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x24	00100100	delete to end of row (clear line)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x25	00100101	roll up 2 (scroll size)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x26	00100110	roll up 3 (scroll size)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x27	00100111	roll up 4 (scroll size)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x29	00101001	resume direct captioning (start caption text)
0x14 (TXT1) or 0x1c (TXT2) or 0x15 (TXT3) or 0x1D (TXT4)	0001C10F	0x2A	00101010	text restart (start non-caption text)
0x14 (TXT1) or 0x1c (TXT2) or 0x15 (TXT3) or 0x1D (TXT4)	0001C10F	0x2B	00101011	resume text display (resume non-caption text)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x2c	10101100	erase display memory (clear screen)
00x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x2D	00101101	carriage return (scroll lines up)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x2E	00101110	erase non displayed memory (clear buffer)
0x14 (CC1) or 0x1c (CC2) or 0x15 (CC3) or 0x1D (CC4)	0001C10F	0x2F	00101111	end of caption (display buffer)
0x17 (CC1/3) or 0x1F (CC2/4)	0001C111	0x21	00100001	tab offset 1 (add spacing)
0x17 (CC1/3) or 0x1F (CC2/4)	0001C111	0x22	00100010	tab offset 2 (add spacing)
0x17 (CC1/3) or 0x1F (CC2/4)	0001C111	0x23	00100011	tab offset 3 (add spacing)

References

↑ "SCTE 21 2012 - STANDARD FOR CARRIAGE OF VBI DATA IN CABLE DIGITAL TRANSPORT STREAMS" (PDF). Society of Cable Telecommunications Engineers. SCTE 21: 13. 2012. Retrieved 4 October 2012.
↑ CEA-608-E R-2014 standard

External links

Closed caption decoder requirements for analog television receivers – 47 C.F.R. 15.119 – From the F.C.C.
Index of requirements documents in text and PDF for 47 C.F.R. 15 – use the 119 link – From the F.C.C.
CEA-608-E R-2014 – Latest revision of the standard from the Consumer Electronics Association

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.