I suspect it is embedded in the Onkyo Player's proprietary file index and not exportable. The Onkyo player app needs its' own file index so that your tracks and playlists can be played immediately after powering on. Otherwise, it would have to wait for the painfully slow Android system re-indexing of all media files on SD cards each time it powers on. I am an extreme case, but it take s a good 30-40 min for Android to index 10K files on my SD cards. You can also see how bad this is by loading an M3U playlist file in the Music directory. It takes a long time for the playlist to even display in the Onkyo player every time you power on the X1 because all the files have to be re-scanned before the M3U files get processed. Again this happens every time you power off/on. The work around to this is as follows:
1) Create M3U playlist files that match the directory structure of your SD card
2) Copy M3U file(s) to the SD card
3) Wait for the painfully long time for the playlist with all the tracks to show up in Onkyo player
4) Once it is fully scanned and available, play track 1
5) Got o view play queue
6) Save the entire queue (your M3U playlist) as a new playlist in the Onkyo app. do this for each M3U file.
7) Delete your M3U file(s) from the SD card
8) Now you can play the playlist immediately after power on instead of waiting forever