The SL NEO platform allows automatic generation and multiplexing of closed and open captions. Information is relevant for the 2.5.52 version and later. Closed captions require a special decoder for viewing, while open captions are inserted over the image.

In EU and Russia, the following technologies for captioning are used: Teletext, IP (DVB) and Open Captions.

Depending on a task, captions may be overlayed in different software modules:

• Overlaying in Program Channel – for captioning local broadcasting or at the moment of a regional insert.
• Overlaying in Playout – for local captioning of the passing signal with no inserts.
• Overlaying in IP Playout – for forming DVB captions.

The structure of naming captions files is the following: MediaID_N_LANG.ext, where:

• MediaID – MediaID of the video file,
• N – number of the caption track (optional),
• LANG – language code in the format ISO-639-2.
• ext – extensions of a file with captions (described in the table “Supported Input Formats”).

Example:

• Mr_Popper_Penguins.mp4 – video-clip,
• Mr_Popper_Penguins_rus.srt – captions in Russian,
• Mr_Popper_Penguins_eng.srt – captions in English.

 or 

• Mr_Popper_Penguins_1_rus.srt – captions in Russian, placed to the first track,
• Mr_Popper_Penguins_2_eng.srt – captions in English, placed to the second track.

Captions may be added to the file at the stage of import to the media database. Files with captions must be located in the folder with the video-clip at the moment of import.

Option	Description
Process Captions	Activates import of captions
Output Options – selecting the output technology
Output Protocol	Selecting the technology for saving captions to the database: SRT File – SRT files will be placed to the media database. CEA-608 – captions will be encoded to the VANC area. CEA-708 – captions will be encoded to the VANC area. CEA-708 with 608 Compatibility Bits – captions will be encoded to the VANC area.
Number Channels	The number of output caption tracks.
Caption Parameters – displaying settings for 608 and 708 captions
Display Mode	Displaying mode
Number of Lines	The number of simultaneously displayed lines.
Number of Columns
708 Anchor Position
708 Vertical Position
708 Horisontal Position
Output Stream N – settings of output tracks with captions
Input Source	The source of captions for the output track. Possible values: Caption Stream – from an SRT file CEA-XXX – from a VANC area of the video file with CEA-608/CEA-708 captions. Setting “Output Protocol=SRT File” during import for a file containing CEA-608/CEA-708 captions in VANC will lead to Caption Extraction: an srt file with captions will be created at the output.
Input Language	Selecting an output track with captions by language.
Input Stream #	Selecting an output track with captions by index. The option is available if Input Language=Any. (Possible values: None, 1-8)

This option may be used in cases, when captions are played via Program Channel. If displaying captions is implemented through the Playout service, you must use the dynamic load of captions.

If files with captions are loaded dynamically, they are placed in a file folder on the disk. For example: Z:\Subtitles. A path to the folder is specified in services settings:

To start configuring closed captions, activate generation of captions and select an output protocol in the configuration of Program Channel or Playout services.

If teletext was used as the output protocol, the Caption streams area will be available for adding/editing captions output tracks. One track equals one teletext page (one language).

The dialogue for adding a caption output track.

If the system of displaying captions in teletext is used autonomously (the channel doesn't have teletext), it is necessary to turn on output of service packets and generation of the 100th page in the window Administrator Control Panel→Manage→Video IO Boards→Playout_N→General→Teletext Options… or Administrator Control Panel→Manage→Program Channels→Program_N→General→Teletext Options….

Besides, you can define VBI Lines to be used to transmit teletext in Teletext Options of the Playout service. Number sof lines must be comma-separated. If the value is empty, the service will define lines automatically.

If teletext is displayed in the IP format (transcoding an SDI signal containing teletext or direct IP broadcasting), you must define settings of conversion to DVB Teletext in IP Playout service settings: Administrator Control Panel→Manage→Video IO Boards→Playout_N→MPEG2 TS Parameters→Teletext.

Parameter	Description
DVB Teletext	Activates encoding teletext to an IP stream.
Teletex PID	Identifier of the stream with teletext captions.
Subtitle Lang
Subtitle Page
Non-Subtitle Lang
Non-Subtitle Page

Configuring is described in the article: Configuring Generation of Closed Captions in DVB Transport Streams.

Creating and editing captions can be implemented by both third-party editing apps and client software NewsCut that includes all necessary instruments.

Control of Teletext closed captions in the SDI signal can be implemented by a TV oscilloscope (Tektronix WFM2300 was used as an example).

Control of Teletext packets in the ANC Data Inspector mode. Select the displaying mode: MEAS→Menu→Display Type→ANC Data Disp.→ANC Data Disp.

Visual control of Teletext is implemented in the window for image output (PICT).

Activate displaying closed captions in the window menu (PICT→Menu→CC/Teletext Sel.→Auto) and select the number of a Teletext page containing captions (PICT→Menu→TtxtB Page→Page number).

Viewing Teletext closed captions in server output signals may be implemented by the Multiscreen client application. Captions displaying settings are similar to the ones in the Airmanager app.

Displaying closed captions for SDI and IP streams is supported in multiscreen processors SL NEO 8000.

Viewing Teletext closed captions in IP streams is possible in the VLC player.

Select Teletext in “Menu→Subtitle→Sub Track”.

After this, you will see a panel to select a teletext page: enter 888.

Open captions can be managed by the Multiscreen client application. In the list of services, select the service that outputs open captions.

Open the IP stream in the VLC player. Select: ‘'VLC→Subtitle→Sub Track→DVB Subtitle- [language]. ==== Control of Subtitles for Database Clips ==== Airmanager and Media Connect applications allow ANC data control in File Monitor and Clip matherial Sheet windows, and viewing captions loaded to the media database, embedded to a video-file and connected via “External Captions Dir” of the media database service in the FileMonitor window. Managing captions in external SRT files of the media database is also implemented in the Clip Material Sheet→Caption Fields'' window.

Control of captions is also available in the playlist window: the Captions column displays available subtitle tracks.

• Test AVI-file with SRT-files of subtitles.
• free_tv_op_47_052018.pdf.
• free_tv_op_42_122012.pdf.
• GOST 50861-96 Teletext system. Basic parameters. Measuring methods.
• GOST R 57763-2017 – subtitles for the deaf or hard of hearing (SDH)