> -----Original Message-----
> From: ffmpeg-devel-boun...@ffmpeg.org [mailto:ffmpeg-devel-
> boun...@ffmpeg.org] On Behalf Of Dominik 'Rathann' Mierzejewski
> Sent: Friday, February 06, 2015 4:51 PM
> To: ffmpeg-devel@ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH 2/3] Use clew instead of cl.h for OpenCL
> 
> Hello, Maneesh.
> 
> On Friday, 06 February 2015 at 11:09, Gupta, Maneesh wrote:
> > Attached is the follow on patch that switches to using clew instead of
> > cl.h
> 
> What's the rationale to switch? cl.h is part of Khronos distribution while
> clew.h seems to be part of clcc with a couple of forks floating around the
> Internet. Is clew packaged in major distributions? It's definitely not in 
> Fedora
> or Debian.
> 
> Regards,
> Dominik

My intention of this entire patch was to allow most systems to compile ffmpeg 
with OpenCL enabled.
Couple of problems with this today is that the location of OpenCL headers and 
libraries is not a standard nor is it easy to figure out this location across 
various platforms. As a result we need to tell ffmpeg the location of the 
Khronos OpenCL headers and libraries using --extra-cflags and --extra-ldflags 
in addition to using --enable-opencl.
Clew, used by several open source projects such as LibreOffice and Blender, 
helps in this regards by not having to depend on the OpenCL static library. 
Additionally by adding it to the ffmpeg source tree, we can completely avoid 
having to pass any additional options for enabling OpenCL, thereby achieving my 
original intent.
If you can suggest any better approach to achieving the intended goal, I can 
work on the required patch for the same.
Also if it helps, below is a response from Martijn who is maintaining clew for 
Blender.
------
Sergey and me forked clew as it was un-maintained and we wanted it to do OpenCL 
1.2 at least. 
We host ours at https://github.com/OpenCLWrangler/clew and have the following 
plans for the future:

- Make more of the code auto generated from official Kronos headers
- Add OpenCL 2.0 support
- Keep it stable and help out where needed to enable our stakeholders ( 
maintainers of OSL / OpenSubDiv ) and users to have a seamless opencl enabled 
experience where possible.

We also have a similar library for Cuda's driver api and recently for loading 
SDL 2.

Since our use of OpenCL is currently mainly the compositor there has not been a 
lot of development in the passed year on the whole clew front.

I hope this helps you,

Martijn
------
Regards,
Maneesh
> --
> MPlayer http://mplayerhq.hu | RPM Fusion http://rpmfusion.org There
> should be a science of discontent. People need hard times and oppression to
> develop psychic muscles.
>       -- from "Collected Sayings of Muad'Dib" by the Princess Irulan
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