The latest build is up at:
http://files.jriver.com/mediacenter/channels/v21/latest/MediaCenter-21.0.39.deb (also in the latest apt repository)
21.0.39 (1/25/2016)
1. Fixed: Bug in calculating the offset from UTC.
2. Changed: MC linux will download the mp3 encoder instead of using the system mp3 encoder.
3. Fixed: Allocation of some files failed on linux when the filesystem didn't support fallocate(). Affected Thumbnails at the very least.
4. Fixed: ARM System Identification.
5. Changed: deb packaging and post-install to integrate MC more into Unity (and probably other desktops).
See the windows 21 log for general non-linux related changes.
21.0.37 (1/15/2016)
Changes from the main branch
21.0.28 (12/17/2015)
1. Fixed: Potential worker thread hang in CListener class, also a potential memory leak.
2. Fixed: Fixed potential hangs/crashes and memory leaks in networking code.
21.0.23 (11/23/2015)
1. Fixed: Memory leak bug introduced in 20.0.123. More apparent if there are lots of windows (from any application) open at once.
2. New: The internal function that provides the OS information to MC is now functional. This fixed a bug in Noire where the window action buttons could have been windows 10 lookalikes.
3. Changed: Internal event handling.
21.0.16 (10/16/2015)
1. Fixed: Thumbnail creation for Videos would often crash JRWorker.
2. Fixed: The TVInfo Expression did not work.
3. Fixed: Change in eventing fixes maximize button on ARM, possibly other subtle changes.
21.0.7 (9/15/2015)
1. NEW: Support for external sidecar subtitles.
2. NEW: Automatic stream selection based on the preferred languages configured in Video -> Subtitles & Languages.
3. Changed: Improved font metrics handling of descents on letters like "g" or "j".
4. Fixed: Leaving fullscreen mode (ie when playing video fullscreen) returns MC to the state is was in before entering fullscreen mode.
5. Fixed: MC behavior with multiple monitors (xrandr) and fullscreen mode. Still needs a bit more work to fully support multiple monitors.
6: Changed: MC will print an error message (to stderr) when unable to open the X display instead of segfaulting.
7. Fixed: The cursor will be hidden in fullscreen mode.
8. Changed: The custom Data is used from the users MC resource area instead of from MC's app library area.
21.0.6 (9/4/2015)
1. Fixed: Issue with crashes when closing the tree during playback when the cover art is displaying in the action window. This could possibly help with other sizing issues.
2. Changed: Skins are copied into the users MC resource area from MC's app library area upon updating to this build and are used from there going forward so they can be modified without requiring root permissions.
21.0.5 (9/1/2015)
1. Changed: Added graphical confirmation of the license installation through the file association.
21.0.4 (8/14/2015)
1. Fixed: The "View Current Log" button on the logging dialog wasn't working.
2. Fixed: Exporting a playlist to HTML didn't open a browser to view the playlist properly.
3. Fixed: Viewing the html of a gallery in preview mode didn't open a browser properly to view the preview.
4. Changed: Internal, method of running an external command.
5. Fixed: Can purchase an upgrade via the usual method (install MC 20 license on MC 21 and follow the instructions).
21.0.3 (8/10/2015)
1. NEW: Improved font support.
2. Fixed: Trial period was broken.
21.0.2 (8/7/2015)
1. NEW: Subtitle Support during Video Playback.
2. Changed: Windows redraw better.
3. NEW: Image support. 2D viewing effects only at this time.