Safe Area settings for Teletext and Closed Captions projects follow similar characteristics - the safe area is defined by the number of characters that can be displayed on any text line. Closed Captions projects provide several options which will be noted later on in this topic.
Teletext settings
One of the Teletext specifics is that teletext subtitles are always displayed by monospace fonts and all characters have the same width. This leaves the maximum number of characters per line as only real indication of the Safe Area:
By specifications, the max. number of characters cannot exceed 42, including any formatting or control code. Formatting codes are added for every color change (text and background) and for changing text's height from normal height to double height or vise-versa. Two additional "Start Box" control codes are inserted in the beginning of every subtitle too to ensure successful display of the text.
This, in essence, limits the usable character limit, without any control and formatting codes, to 37 or 38.
For CEA-608 closed captions the screen is divided in 32 columns which also means that there might be no more than 32 characters for each text line. Due to compatibility the Maximum characters per row is limited to 32 in EZTitles.
The very same applies for CEA-708 closed captions but for projects with 16:9 aspect ratio the screen is 42 columns wide instead so up to 42 characters can be entered. The Maximum characters per row setting will change accordingly when changing the project settings to CEA 708 mode and selecting 16:9 aspect ratio.
There some additional options too:
Use extended character set |
Enables the use of characters from the Line 21 extended character list set.These are basically vowels commonly used in the French, Spanish, Portuguese and Italian as well as some additional symbols (curly brackets, single quotes and etc.). |
Double control codes |
Control code characters are duplicated to ensure safe encoding during transmission. |
Use ENM control code at the beginning of pop-on captions |
Some closed captioning formats (CPC-715 .onl and Caption Inc .cin) require the ENM (Erase Non-Displayed Memory) control code to be present in the CC data for each caption but this adds a frame or two to the respective Time to process. The option can safely be switched off when importing or exporting any of the remaining closed captioning formats. |
Interleave CC data for 23.976fps to maintain 30/1.001 pairs per second |
The option is available for projects with 23.976fps frame rate and changes the captions encoding model in accordance with the "CEA-708-B" standard. By default the option is turned off which means that 2 pairs of CC data will be encoded for every video frame. When the option is turned on, 3 pairs of CC data will be encoded for every other frame. Or in other words, turning the option on enables 25% more text to be encoded over the same period of time which will also account for decreasing the "time to process" required for each caption. Note: Turning the "Interleave" option is recommended only when confirmed that the particular service provider acknowledges the "CEA-708-B" recommendations. Although the "CEA-708-B" standard was released in 1999 it appears it might not be fully adopted by every service provider which may result in rejections. |
Blank between pop-ons |
The blank between pop-ons option is used instead of Minimum Interval in Closed Captions, the default value for it is 2 frames. |