Cavena Interfaces to external systems

Cavena subtitling systems supports a varity of interfaces to external systems.


Planning system interface

Cavena has two functions for planning system interfaces:

Program ID file name check. An optional text file interface where the Traffic system lists all existing Program IDs in a text file which is placed on the network so it can be read by SAM. This is used by SAM (Cavena Subtitle Archive and Management) to prevent subtitle files with wrong File IDs to be entered. A subtitle file with a File ID that is not a valid Program ID will not be accepted by SAM.


SQL capability in the SAM database. The SAM has a database that will allow SQL questions and this can be utilised by the Traffic system to search for available files or other subtitle data information.


Playlist interface

STC has a playlist interface where STC will read playlists from a directory on the network. The playlist is one text file per 24 hour period and there are several playlist formats to use. The fields used are Subtitle File ID / Time of Day / S.O.M. / Segment info / Subtitle Languages / PGM name. There is one format that uses an additional field with a Material ID. This is used in systems where the automation system uses a tape number ID different to the Program ID. To use this additional field it is necessary that the cross-reference between the Program ID and the Tape ID is established already in the playlist from the planning system or automation. The playlist is sorted according to time of day and the playlist will be displaying in the STC. Time of Day will however normally not trigger the start or stop of subtitles as this is performed by the Automation interface.


Automation interface

Cavena has interface to most automation systems. The interface is either serial interface RS 422/RS 232 or TCP/IP based. The following commands are used: STOP with channel ID. PREPARE with Program ID and Channel ID. START with channel ID. The Prepare command will select the event with requested name that is close in time to be executed. Should there not be an event with the correct name close in time but still somewhere in the total playlist then the system will start that event.


Automation can also build playlists in STC using the REQUEST command, query the SAM database for file availibility and also query the STC for each channel status, including timecode, transmission port and file errors.
Cavena is also ready to supply any automation manufacturer with Cavena protocol against a signed NDA should the customer choose to change to an automation system that we yet do not have an interface for.


Video signal inputs

The STU uses timecode as a reference to playout subtitles from files. This is either a composite or SDI/HD-SDI signal carrying VITC, ATC_VITC, LTC etc.


STU is also capable of extracting subtitles from an incoming signal carrying teletext or EIA-608 subtitles and transcode these into any output format.
STU also provides interfaces for live subtitling stations, for live typing of text into STU. Cavena can provide STU protocols against NDA, but STU also supports several live workstation manufacturers protocols.


In addition to this, STU can receive teleprompter input and reformat this as subtitles for transmission.


Encoder interfaces
Cavena has three types of proven interfaces to encoder/mux systems: RS422 (in use for early NDS systems). TCP/IP (in use by Tandberg and Thomson) and ASI (in use by the majority of systems).


Cavena also has interfaces to other encoder systems and will write interfaces for additional manufacturer that the customer chooses as supplier.