MPD is definitely much more sophisticated and bigger project.
MPD is primarily client-server music player with streaming support.
Audioserve is more about serving audio files over HTTP protocol with couple of utilities/enhancements like possible audio transcoding, support of playback position sharing, support for chapterized audio files (m4b) and couple more.
"bag of tricks to smooth out perceived latency and fault tolerance."
Agree - audioserve is now handling this with quite simple trick - just cache ahead couple of tracks/files from current folder (aka audiobook), so responsibility is move to client.
Surprisingly this simple trick did work for me for years (as I'm intensive user of audioserve). It kind of depends on file/chapter duration - but for most common cases - which are beetween 5 mins to say 90 mins it did work fine.
Historically only Android client was using this caching, but with new web client https://github.com/izderadicka/audioserve-web and broad Service Worker support in browsers it is also available in browser.
Concerning audiobookshelf, I see it other way around, because I think audiobookshelf came after - so it's contender to audioserve. But it is definitely nice app. I tried and did like some things (especially turning books into HLS streams), however I ran into couple of issues, when trying:
- audiobookshelf requires some rules for directory structure (which caused that some subfolders from my collections were not loaded), audioserve serves any directory structure
- bigger collections - for collections with 10k audiobooks audiobookshelf was just too slow it went on for couple of hours loading before I kill it. Audioserve is able to handle within collections scan in tens of minutes.
Adding not so common audio formats to audioserve will not be so different. We'll just need to add mime types (and extensions), that are recognized as audio.
Also we will need to enforce mandatory transcoding for such formats.
Anything, which is supported by ffmpeg can be considered.
Looks like Amazon is retiring Alexa?
Audioserve has generic web client - but not sure if it works on Alexa. If there are problems try with transcoding set to None.
No unless somebody will make plugin for it - audioserve has it own API. I though about implementing Subsonic API, but it's design is much different from how audioserve works, so it'll require too much "interface code", so I doubt I'll get to it.
Thanks for nice words, though I do suffer from above average affinity to beer (and Rust) I consider myself decent person.
As I'm using audioserve myself, I try to evolve it continuosly, however my view of good simple audiobooks streaming server might be quite optioned (prefer textual information to covers, strong preference of opus codec, etc.), but do not hesitate to share your experiences and ideas via issues on project.
Apple platforms has by default problem with Auddioserve - my choice of default audio codec is opus (in ogg container) and Apple support of opus is not very good, to put it mildly (I think one can make Safari on MacOS to support opus, but no chance on iPhone/iPad AFAIK). So for Apple you'll need to change the default configuration. First thing to try is to put transcoding to None on client. Thus formats supported by Apple like mp3 will work. Next task is to change transcoding on serve and use aac instead of opus. Recently I added possibility to choose transcoding based on User-Agent string (regex match).
