public Event.stream_start (string stream_id)
Create a new STREAM_START event.
The stream start event can only travel downstream synchronized with the buffer flow. It is expected to be the first event that is sent for a new stream.
Source elements, demuxers and other elements that create new streams are supposed to send this event as the first event of a new stream. It should not be sent after a flushing seek or in similar situations and is used to mark the beginning of a new logical stream. Elements combining multiple streams must ensure that this event is only forwarded downstream once and not for every single input stream.
stream_id should be a unique string that consists of the upstream stream-id, / as separator and a unique stream-id for this
specific stream. A new stream-id should only be created for a stream if the upstream stream is split into (potentially) multiple new streams,
e.g. in a demuxer, but not for every single element in the pipeline.
create_stream_id or create_stream_id_printf can be used
to create a stream-id. There are no particular semantics for the stream-id, though it should be deterministic (to support stream matching) and
it might be used to order streams (besides any information conveyed by stream flags).
Identifier for this stream
the new STREAM_START event.