What is dleyna renderer?

I recently upgraded to 17.10 and today noticed a new process causing apport bugs to be filed. dleyna-renderer-service Google takes me to its Github page which "explains":

dleyna-renderer is a library for implementing services that allow clients to discover and manipulate Digital Media Renderers.

Huh? So I looked for a man page with apropos dleyna and found nothing. I then turned to Apt:

$ apt show dleyna-renderer
...
Description: DBus service to interact with DLNA Digital Media Renderers
 dleyna-renderer is a DBus user session service that allows clients to
 discover and manipulate DLNA Digital Media Renderers (DMR).
 .
 dLeyna is an umbrella project hosting a number of middleware components
 designed to make it easy for developers to integrate DLNA functionality into
 their applications.

This is a bit better —we've said DLNA which at least means something to me— but I'm still confused as to what this is actually supposed to do within my Ubuntu install. I can account for nearly every other process on my system. So...

• What does dleyna-renderer do in Ubuntu?
• How can I use it?
• Why do I want it?
• What are the security ramifications to it running?
• Is it safe to remove?

And layman's terms please, folks. Maybe not ELI5, but if you use a phrase like "Digital Media Renderers", explain what you're actually talking about.

What does it do?

The DLNA spec allows devices on a network to receive and send media (say, videos or music). You can play media on your system on other devices on your network, like an XBox, or a TV, or your Pi running Kodi or Plex, etc.

The spec is pretty widely supported. Several industry players back it, meaning it's more likely to be available on an average consumer device as time goes by.

A Digital Media Renderer is something that can play media received using DLNA. So, "discovering and manipulating Digital Media Renderers" essentially means that apps can use this library to see if there are DLNA-capable devices on the network, and send media to them (and then control playing that media, hence "manipulate"). Essentially, this library implements the DLNA spec's sending media part. (The dleyna-server library, OTOH, implements the receiving part - it's used to work with a DLNA server.)

How can I use it?

I'm not sure why it's installed on your system, but aptitude suggests one reason on 16.04:

$ aptitude why dleyna-renderer
i   plymouth     Suggests   desktop-base
p   desktop-base Suggests   gnome | kde-standard | xfce4 | wmaker
p   gnome        Depends    gnome-photos (>= 3.14)
p   gnome-photos Recommends dleyna-renderer

And, yes, GNOME Photos does support it (as of 3.14):

Status: Completed

With this, we want to turn GNOME Photos into a Digital Media Player (or DMP) that can browse DMSes (DLNA Media Server) on a local network. It will also extend existing DMC (DLNA Media Controller) capabilities. Currently it can push the local/cloud content to DMRs (DLNA Media Renderer). With it acting like a DMP now, content can be pushed from DMSes to DMRs.

In the hamburger menu (☰) should be an option saying "Display on"... I don't have any DLNA devices, so the popup that shows is empty for me.

Kodi and Plex also support it. I'm not sure what else on Ubuntu supports DLNA.

Why do I want it?

Unless you have something on the network to play to, or receive from ... you don't need it.

What are the security ramifications to it running?

Not sure, need to research more on that. The dleyna project is supported by Intel, though, so I'd expect good security support.

Is it safe to remove?

It should be. Even on 17.10, it's only a recommended dependency of gnome-photos. At any rate, it's nothing mission critical even on the desktop.