- _source – the sender
- _target – a single recipient or chatroom
- _time_publish_start – the time the transmission started
- _media_identification – an opaque value, currently not specified
- _nick — nickname of sender. optional.
Default psyctext template is "[_source] starting to transmit media at [_time_publish_start]."
uses the same variables and template as _message_audio. Merely the change in method name hints at the different type of media.