[x265] xp support

[Steve Borho]

On Tue, Mar 25, 2014 at 11:25 AM, Roger Pack <rogerdpack2 at gmail.com> wrote:
> Hello.  I noticed in a recent discussion that seemingly windows xp
> support had been "dropped" to clean up code:
>
> http://forum.videohelp.com/threads/357754-%5BHEVC%5D-x265-EXE-mingw-builds?goto=newpost

I would describe the situation more as we needed to use a
synchronization primitive (condition variable) in order to prevent
deadlocks and that primitive is not supported on XP.  This wasn't a
code cleanup, it was fixing a serious race hazard.

> This does make it a bit painful for distributors who want to
> distribute (for instance) ffmpeg with libx265 support, but also still
> want to distribute "one executable" for all our users (including XP
> users)...
>
> Just throwing this out there, but maybe x265 can use pthread style
> condition variables then it be compiled against win32-pthreads project
> or what not, when needed.  Or something like that.

Adding support for a second threading library on Windows just for XP
is a non-starter, but I would welcome a patch that adds an XP safe
ThreadSafeInteger class.  Option 3.3 from
http://www.cs.wustl.edu/~schmidt/win32-cv-1.html looks to be a viable
solution, but it will be some time before this makes it to the top of
my TODO list.

-- 
Steve Borho