Relationship between data broadcast and subtitle, teletext, and close Caption

Answer in the Forum:
1. data Broadcast, I don't know what the data broadcast you're referring to, but the TTX and sub transmitted in the DVB-T and mheg standards are called data broadcast. in China, the TTX information in the analog channel is called text information, that is, data broadcast. It may be wrong. You can check it again.

2. teletext. it can be divided into digital TTX and analog TTX. the European role is digital TTX, but analog TTX is used in the UK. The TTX information in the UK is stored in mheg, which is a function of mheg. TTX is what we call text and text information in China, but the digital TTX is more complex. It is transmitted in a stream by a program, the interface corresponding to this program is provided by the supplier in the country and can be requested from the supplier. TTX is divided into magazine and page. there are a total of four magazine, which are selected by the four-color key. Each magazine contains many pages. the standard for DVB-T sets paga to a maximum of 2000. that is to say, you need to set aside 2000 pages in the temporary storage to make the TTX play normally. TTX has nothing to do with subtitle and CC. It is totally different. in particular, TTX only exists in the DVB information and analog
Channel.

3. both subtitle and CC are subtitle types. CC is a hidden subtitle. it is a standardized Coding Method for adding text to ntsc TV signals. the built-in decoder or independent decoder of the TV can display text. after 1993, more than 13 inch of TVs sold in the United States had a closed caption decoder. closed Captions can be used in DVDs, video bands, broadcast TVs, cable TVs, and so on. CC is also transmitted based on a specific code. The Code contained in American CC adopts a C-language-like code. subtitle is just a simple and linguistic subtitle.
The difference between the two is from the UI aspect. the subtitle is just a seed layer, which is displayed in the form of layer superposition. The processing method is the same as that of the UI Layer. CC is displayed on the same layer as the UI in a display function. It does not need to be superimposed when processing CC. in addition, CC has the following functions:
A. Modify the font, including the font size, color, and style.
B. Modify the background color.
C. CC display style, for example, flashing display style.
For CC, Sarnoff in the United States provides a series of test streams, including all CC functions. therefore, CC is a program that is written and received by our interface program and decoded according to the rules. It is a function, and subtitle is only a simple text file, it is displayed in the form of a stacked UI Layer.
I don't know whether it is clear or whether you are welcome to discuss anything wrong.