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Persian/Arabic Teletext


ahmad6687

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Thanks for the file. It's the first Persian DVB-T sample in my collection :) and I had a look at it with the TransEdit Analyzer:

 

The language designation in the teletext headers is ambiguous.It could be Greek, Rumanian or Arabic. And the broadcaster doesn't clarify it by providing additional language information in the PMT. So DVBViewer uses the Greek character set as default. However, this can be changed. Go to Settings -> Options -> EPG -> Teletext -> Character Set Preferences, tick the Arabic checkbox and click OK. The change will become visible as soon as the current teletext page is updated by the broadcaster.

 

The teletext specifications don't specify a Persian character set, and I don't know if the Persian characters are covered by the Arabic character set. Please let me know if it looks ok after the settings change.

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thanks a lot for quick reply

it works fine!

 

can you say me about language information in PMT?

and where is inserted?

 

Regards,

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can you say me about language information in PMT?

and where is inserted?

 

Usually it is part of the teletext descriptor within the Program Map Table (PMT), which is one of the broadcasted Service Information Tables (SI). There are teletext descriptors in your file - otherwise receivers would not recognize the streams as teletext - but they are empty. I think it is not so important because mostly people will use localized DVB-T receivers and TV sets that are selecting the correct character set by default. However, international software like DVBViewer needs the language information.

 

You can see it in the TransEdit Analyzer (download from the DVBViewer Members Area, please read the installation instructions in the ReadMe). The manual contains an introduction to SI tables.

 

The attached Analyzer screenshots show the PMT of a German DVB-T channel that contains a complete teletext descriptor including the ISO language code "deu", and for comparison the PMT of a Persian channel. The third screenshot shows a part of the Persian Event Information Table (EIT) containing EPG data. Here the language is correctly specified as "ira". However, since the Persian EPG uses Unicode character coding (UTF-8), the character set is no problem. DVBViewer would display the EPG correctly even without the ISO language code. Unfortunately teletext is a very old system and not designed for using UTF-8.

 

As a result of your report I will add the "ira" language code to the teletext language detection and map it to the Arabic character set. Maybe it will work out in future...

Zwischenablage01.png

Zwischenablage02.png

Zwischenablage03.png

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can you send that TS file? for more compare?

 

Sure. I have recorded 30 seconds of German DVB-T. In order to keep it small the file only contains the SI tables (PAT, PMT, SDT etc.), but no video, audio and teletext. Simply drag and drop the TS file on the TransEdit icon or into the TransEdit main window.

Terrestrial (EUR) 690.zip

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  • 2 months later...
hi


thanks a lot for previous answer


can i tell me, where iso language code is added in transmission chain? Teletext Generator or Encoder or ...?


you said: "However, since the Persian EPG uses Unicode character coding (UTF-8), the character set is no problem." and in DVBViewer is correct but EPG characters in some other softwares and set top boxes is shown wrong!

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can i tell me, where iso language code is added in transmission chain?

 

I don't know exactly. It depends on the broadcaster. It's added when the PMT (Program Map Table) for the service in question is created and added to the transport stream.

 

you said: "However, since the Persian EPG uses Unicode character coding (UTF-8), the character set is no problem." and in DVBViewer is correct but EPG characters in some other softwares and set top boxes is shown wrong!

 

Maybe because they don't support UTF-8 (8 bit Unicode) character coding. Unicode is very flexible. It covers almost all characters worldwide, even Chinese and such. For receiver manufacturers this may be a problem, because for fully supporting Unicode they must provide very large character tables and fonts, which is a cost factor. However, PC software should be able to handle it, since Windows provides all the required fonts.

 

The broadcaster can try to circumvent this problem by using a more limited character coding, e.g. the ISO/IEC 8859-6 Arabic character set. Read more about it in annex A of the DVB specifications for service information (SI):

 

http://www.etsi.org/deliver/etsi_en/300400_300499/300468/01.13.01_40/en_300468v011301o.pdf

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  • 4 years later...

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