Timing Considerations for Hmong Closed Captions

DCMP conventions for Broadcast closed captions
Character Set
Traditional video closed captions only support the basic and extended ASCII character sets.  

CTA 608 closed captions can only support standard ASCII letters, numbers, and punctuation  
(, . ? / : ; ” ‘ [  ] (  ) ! @ # $ % & ( ) < > – + =)  
and the following special diacritical and symbol characters
á é í ó ú à è ì ò ù ä ë ï ö ü â ê î ô û ç ã ñ õ å ¿ ¡ ¢ £ ¥ © ® ™ ° ß §.

CTA 708 closed captions can support additional non-Western languages.

CTA 608 / 708 closed captions do not support that the Romanized Popular Alphabet characters, which uses final consonant symbols as tone markers, for captioning Hmong dialogue.

Note: The main Hmong dialects spoken by Hmong Americans are Hmong Daw (also called White Miao or Hmong Der)
and Mong Leeg (also called Blue/Green Miao or Mong Leng.)
 
Sentence Breaks
A new closed caption begins after sentence-ending punctuation
. ? !
 
Line Limits
Captions are displayed in caption lines. A caption is limited to four 32 characters lines.  

We cannot split a word that would cause the line to exceed 32 characters. We must start that word on the next caption line.  
Ideally, a caption does not contain more than two lines for easy reading.

With Hmong containing an estimated 30% more words than a comparable English sentence, two lines might not be enough.
 
Character Limits
TV closed captions are limited to displaying 32 characters/line
with a maximum of 4 caption lines (128 characters) per caption.
 
Display Time
Ideally, an English caption is displayed for a minimum of 1.17 seconds to allow time for it to be read.  

Ideally, an English caption is displayed long enough to bring the WPM rate down to 300 WPM or less to allow time for it to be read. To meet this practice for English captions, we might start displaying a “wordy caption” a fraction of a second early or display it for a second or two after the dialogue ends to give an average reader time to read the caption.  

Some Hmong captions may need to be displayed at greater than 300 WMP to keep the caption text aligned with the dialogue.
 


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About Me

Hello there! My name is Vicki Kipp, and I am a closed caption maker. Making closed captions is time consuming and complicated, so this blog is a collection of all of the knowledge and experiences I have gained. I hope my collection of tips and tricks might help you with your closed caption work the way it has helped me!

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