Hi Nathan!
We'll be happy to see the integration happen. Thank you for pursuing this with the JRiver team. The API and command line options (
http://tuneblade.com/Developer/TuneBlade%20Command%20Line%20Options.pdf) were primarily developed to enable such integration for a professional multi-room audio system vendor. Their system consist of a headless appliance which is basically a Windows PC running their software controlled by mobile apps. They run 8 TuneBlade instances in the background for supporting 8 zones. (Running multiple instances of TuneBlade is possible by the command line option 'isolate'). Each TuneBlade instance is controlled by a specified port number in the command line options. The audio is piped from their software through 8 Virtual cable pairs (one for each TuneBlade instance). They configure the audio capture settings (Virtual cable endpoint) of TuneBlade through the HTTP API, and then control the selection and volume of AirPlay receivers through this API. If needed, the JRiver team can feel free to ask any query to better understand the integration.
We think, having DLNA rendering capability within TuneBlade will not be inline with the functionality of TuneBlade, so we suggest using some other DLNA renderer (Kodi?), and TuneBlade can capture the audio on the specified audio endpoint where the rendered audio is played. In essence, Kodi + TuneBlade can be a DLNA to Multi-room AirPlay bridge, just like TuneAero+TuneBlade is an AirPlay to multi-room AirPlay bridge. For integration with other software, we recommend the audio endpoint method instead of using DLNA.
Thanks,
The TuneBlade Team