Flat/merged file system for devices with memory card support

[mlt]

Currently external memory card appears as another directory (at least on my Sansa Clip+). It introduces some hassle when browsing and when dealing with playlists created elsewhere like from my collection on PC. I know that I can properly tag everything and just use database  But it just hides the issue.

I wonder if it worth investigation to "merge" filesystems on internal memory and external card, i.e. to show the content from internal memory overridden by the content from memory card. That is if I try to play some file from my playlist it should look for it on memory card first, then in internal storage. If I have same folders, then either to merge their contents recursively, or simply to completely override that folder from internal memory by the content from external card.

I'm not sure how to better implement it. I guess extra level of indirection would be an overkill. So if there are no devices with more than 1 extra memory slot, then maybe something simple like

Code: [Select]

if (found on <microSD1>) {play from <microSD1>}
else {play from main memory/}

would be enough while looking for song, and merged list while browsing.

[saratoga]

This is something we want:

http://www.rockbox.org/wiki/SummerOfCode2010#Make_multi_45volume_targets_look_like_a_single_volume_40like_unionfs_on_linux_41

http://www.rockbox.org/wiki/SummerOfCode2011#Make_multi_45volume_targets_look_like_a_single_volume_40like_unionfs_on_linux_41

Theres various ways it can be implemented.  Either as a special file system spread across two volumes, as a file tree mode where both volumes are merged (the open source media player XBMC has a fantastic implementation of this that works across multiple file system types), etc. 

The problem is mostly just that no one has taken the time to do it.

[mlt]

WoW! Sweet!

get rid of the ugly hack currently in use (which has its uses but also its drawbacks)

What is this about?

Are there any players with more than two volumes, i.e. 2 external card? I feel like it may be an overhead to maintain virtual filesystem on such low-resources devices. I understand that "if/else" is not an elegant solution, but maybe is it enough?