[FFmpeg-devel] [PATCH 1/2] libavutil/libavfilter: opencl wrapper based on comments on 20130401

[Michael Niedermayer]

On Thu, Apr 04, 2013 at 08:40:10PM +0800, Wei Gao wrote:
> 2013/4/4 James Almer <jamrial at gmail.com>
> 
> > On 04/04/13 12:36 AM, Wei Gao wrote:
> > > 2013/4/4 James Almer <jamrial at gmail.com>
> > >
> > >> On 02/04/13 6:46 AM, Michael Niedermayer wrote:
> > >>>> Since unlike in atomic.c we have init() and uninit() functions here,
> > >> there's no need
> > >>>> to have a statically allocated mutex. We could call
> > >> pthread_mutex_init() and
> > >>>
> > >>> the init and uninit themselfs must be thread safe, also register is
> > >>> called before init and must be thread safe
> > >>
> > >> As things are right now the code wont compile unless you use pthreads or
> > >> no threading
> > >> at all (See ticket #2422).
> > >>
> > >> So the code either needs to be changed to allocate the mutexes
> > dynamically
> > >> (Which will
> > >> let us use the wrappers), or we make configure abort when trying to
> > build
> > >> with OpenCL
> > >> support and w32threads or os2threads enabled.
> > >>
> > >> Ideally, the latter if implemented should be a temporary solution until
> > >> the former is
> > >> implemented instead.
> > >>
> > >> Regards.
> > >>
> > > Hi, I want to ask a question, does it mean that the OpenCL code can't be
> > > used  in w32threads or os2threads? Is there any solutions to solve that?
> > > Thanks
> > > Best regards
> >
> > Right now, it fails to compile with anything except pthreads or no
> > threading at
> > all: http://ffmpeg.org/trac/ffmpeg/ticket/2422
> >
> > And as for a solution, making the mutex dynamic instead of static should
> > allow
> > us to enable this with all threading types using the wrappers, but I'm not
> > sure how to properly implement that.
> >
> > thanks, can I add a function to init the mutex and note that it should be
> called in the main thread to init the mutex? I think codecs also has this
> problem. I saw that the init function is in pthreads.c, should I add a init
> thread function for opencl in it?

This may be difficult in some use cases
consider a libA and a libB that both use libavfilter
a user application using both libA and libB could call either libs
init function in either order (if they have init functions at all)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The greatest way to live with honor in this world is to be what we pretend
to be. -- Socrates
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