This module contains an element capable of sending EBU teletext data from a transport stream to the TV using the VBI resource provided by the Hardware Abstraction Layer (HAL) through the Hardware Abstraction Interface (HAI).
Module Name | Teletext VBI element |
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File Name | libteletextvbi.so |
Class Count | 1 |
DVB Teletext VBI Inserterr in typical pipeline.
The teletext VBI element fetches the teletext data from the PES stream. The element depends on the teletext page information being previously decoded from the teletext_descriptor of a DVB encoded stream (ETSI EN 300 468).
Name | Teletext VBI Descriptor |
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Version | 1 |
Interface Name | IElementDescriptor |
Binding | C++ |
Name | DVB Teletext VBI Inserter |
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Type | Intermediary |
Priority | 500 |
Input Formats | MPEG-2/Transport Stream/Multi Subtitle |
Output Formats | MPEG-2/Transport Stream/Multi Subtitle |
Key | Input | Output |
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_ActiveTeletextStream | Produced | Committed |
_TeletextStreamList | Required | Committed |
On ISink::Activate(), it opens the HAI VBI resource instance 0 (zero) in exclusive mode. The HAI resource is closed on ISink::Deactivate().
The element filters the stream based on the value of the _RequestTeletextStream blackboard parameter, which holds the id of the teletext stream selected by the user. If this parameter does not exist, the element chooses the first stream in the _TeletextStreamList as default. The _TeletextStreamList parameter is described in greater detail in the Complex Metadata section.
The element decodes all PES packets having the stream_id field set to private_stream_1 (0xbd). When a complete VBI field is fetched it is sent to the VBI resource.