I have figured things out - BubbleUPnP logs were helpful. I can now select (either from Id MC or JRemote) a zone like "there: living room (dlna)" and play music. This is in fact a Chromecast Audio (CCA) device, dlna instance created by BubbleUPnP on my Windows Server (always running). The reason it wasn't working initially was an audio format issue. I realized finally that settings for this were controlled by "Server Add or configure dlna servers". Mode was set to original, which tried to play my ALAC files which CCA doesn't support. Once I chose Mode to be Specified output format, and format = PCM 24 bit, music started playing. Bubble logs were showing file format as MP4 (my ALAC) initially, and WAV once I got it working.
Some things to note:
- I had some time ago created several DLNA server instances from previous experiments with 3rd party renderers. To solve my problem I deleted all of them so now just have generic dlna. With muitiple dlna server instances, it is not clear to me how you assign those to a renderer/zone. That is, if I have multple dlna servers, how do I know which one is feeding my "There: living room (dlna)" zone? Anyone?
- there is a transcoding option in Bubble, but I kept this turned off as I didn't want to introduce unnecessary transcoding. In fact on my windows server instance of Bubble, the ffmpeg transcoder isnt working (some error). In any case I am succeeding without that aspect of BubbleUPnP.
- I know specifying format under dlna settings have changed as of mc23. My server is mc21 still. One point of confusion is that format=pcm 24 bit I believe is actually calling for wav transcoding. For me, calling it wav might be more intuitive. I kept seeing pcm 24 and thinking it was only referring to bit depth - realize now that isnt the case. I think ...
- My windows server is a microsoft whs (I know this is ancient but for me it still serves a useful function, no pun intended) running mc21. I was not able to upgrade mc to 24. No errors just nothing after initial file unpacking. This might not be right place for question, but, what version stopped working with whs (windows 2003), or is this something that could be fixed?
- my motivation for using chromecast is finding that elusive perfectly synced whole house audio solution. I can say that when it works it is very good - I create a group in google home and then let bubbleUPnP create a dlna instance. Unfortunately, the other source in my group is an Onkyo AVR with chromecast built-in. I discovered that Onkyo's implemenation is lacking - it did not work with higher res riles - stuttering etc even with lan connection. I know from other experiments two cca devices (the purchased ones) work really well as a group.