Astra is described as 'professional software to organize Digital Broadcasting Service for TV operators and broadcasters, internet service providers, hotels, etc. Astra acronym for "Advanced Streaming Application"' and is an app in the Video & Movies category. There are three alternatives to Astra for Linux and Self-Hosted solutions. The best alternative is Tvheadend, which is both free and Open Source. Other great apps like Astra are DVBlast (Free, Open Source) and DVBStreamer (Free, Open Source).
DVBStreamer is an console based application to stream DVB/ATSC service(s) over UDP or to a file. It is more that just an app to stream AV though and feature a simple plugin architecture to allow more features to be added.