I think you can do this:
- Create a BufferedWaveProvider.
- Pass this to waveOut.Init.
- In your MusicDeliveryCallback, use Marshal.Copy to copy from the native buffer into a managed byte array.
- Pass this managed byte array to AddSamples on your BufferedWaveProvider.
- In your GetAudioBufferStats callback, use bufferedWaveProvider.BufferedBytes / 2 for "samples" and leave "stutters" as 0.
I think that will work. It involves some unnecessary copying and doesn't accurately keep track of stutters, but it's a good starting point. I think it might be a better (more efficient and reliable) solution to implement IWaveProvider and manage the buffering yourself.
I wrote the ohLibSpotify wrapper-library, but I don't work for the same company anymore, so I'm not involved in its development anymore. You might be able to get more help from someone on this forum: http://forum.openhome.org/forumdisplay.php?fid=6 So far as music delivery goes, ohLibSpotify aims to have as little overhead as possible. It doesn't copy the music data at all, it just passes you the same native pointer that the libspotify library itself provided, so that you can copy it yourself to its final destination and avoid an unnecessary layer of copying. It does make it a bit clunky for simple usage, though.
Good luck!