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Manual configuration

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ZXGuesser edited this page Jan 17, 2023 · 5 revisions

The VBIT2 binary generates a teletext packet stream in t42 format on stdout, to be piped to another program such as raspi-teletext.

Alternative output formats can be selected using the --format command line argument:

  • t42 – The default 42 byte format.
  • raw – As above but includes the three byte clock run-in and framing code. i.e. 45 byte packets.
  • PES – A Packetized Elementary Stream for multiplexing into an mpeg transport stream for DVB-TXT.

The pages in the teletext service are loaded from .tti page files in the directory given by the --dir argument on the command line.

Configuration settings for the service are read from vbit.conf in the page directory. VBIT2 also checks for a vbit.conf.override file which enables overriding individual settings without altering the main configuration file. (For example where a public service is retrieved from a version control system).

The vbit.conf file is a text based key=value format (ini style). An example is provided in the VBIT2 source.

The following keys are defined:

  • header_template – A 32 character string defining the teletext page header.
  • initial_teletext_page – Defines the initial page number (and optional subcode) sent in the Broadcast Service Data Packet. Defaults to 100:3F7F.
  • row_adaptive_mode – Controls whether VBIT2 should omit blank page rows. Defaults to false
  • network_identification_code and country_network_identification – Unique 16 bit hexadecimal codes assigned to television networks in ETSI TR 101 231. Default to 0000.
  • full_field – Non-multiplexed teletext transmission. Not currently implemented.
  • status_display – A 20 character string sent in the Broadcast Service Data Packet.
  • subtitle_repeats – Number of times a subtitle transmission is repeated when using the Newfor subtitle interface.
  • enable_command_port – Enable the network [Command interface]. Defaults to false.
  • command_port – TCP port number on which the command interface listens. Defaults to 5570.
  • lines_per_field – Specifies the number of VBI lines required per video field. This value must match the rate at which packets are consumed. Defaults to 16.
  • magazine_priority – Set the priority of each magazine where 1 is highest priority and 9 is lowest. These are the initial value of internal counters which are used to determine how often a magazine should generate a packet. The values correspond to magazine 8,1,2,3,4,5,6,7. Defaults to 9,3,3,6,3,3,5,6.

Magazine specific enhancement data (packet 29) can be configured using special page files.

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