[FFmpeg-devel] [PATCH] configure: autodetect OpenCL headers and ICD loader

[Gupta, Maneesh]

> -----Original Message-----
> From: ffmpeg-devel-bounces at ffmpeg.org [mailto:ffmpeg-devel-
> bounces at ffmpeg.org] On Behalf Of James Almer
> Sent: Thursday, May 28, 2015 10:06 AM
> To: FFmpeg development discussions and patches
> Subject: Re: [FFmpeg-devel] [PATCH] configure: autodetect OpenCL headers
> and ICD loader
> 
> On 28/05/15 12:28 AM, Gupta, Maneesh wrote:
> > Attached is a patch that enables configure to autodetect the presence of
> OpenCL headers and ICD loader. If the necessary headers are found, the
> OpenCL infrastructure compilation is enabled as well. Note that this does not
> modify the runtime behavior in any way. Execution of the OpenCL code path
> still requires the user to explicitly enable it.
> >
> > Please review the patch and share your comments on the same.
> >
> > - Maneesh
> 
> I personally don't agree OpenCL should be autodetected.
> 
> Currently, only the so called "system" libs are autodetected (zlib, iconv,
> pthreads, the like). Open*L, decoding/encoding libraries, and other
> miscellaneous libraries are enabled only if explicitly requested.
> If we enable one by default, then there's no argument against enabling
> every other as well ("Why this one but not that other one?"), and suddenly
> default builds become bloated and automated scripts get potentially broken
> until adapted.
> 
> Lets keep default builds as lightweight as possible, and allow people to
> explicitly enable the functionality they require.

[Gupta, Maneesh] Apologize for the delayed response. However grep'ing the string "autodetect" in the configure script throws up several "non-system" libs including D3D11VA, DXVA2, VAAPI, VDA, VDPAU, sdl. Why are they turned on by default? Several of these non-system libs enable use of hardware acceleration. OpenCL is similar in nature with a key difference that it is more platform/OS agnostic and can run on both CPU as well as GPU.