[FFmpeg-devel] [PATCH] configure: support static libnpp [v2]

[Andreas Håkon]

Hi Hendrik,

I don't like that there is a separate configure option. We can link to
other libraries dynamically or statically depending on what is found,
without needing two configure options per library.

I understand. However, this is not really true for libnpp*.
Let me to explain about this special case:

If you like to compile FFmpeg statically you can do it. However, you link all or none.
And in the case of libnpp* if you link with regular shard objects, then you need to have all CUDA SDK libraries installed in your computer.
However, if you link to the static version of this library then you need to install only the NVidia driver.

The trick is the dynamic loading of the library "libcuda.so.1" in the source code of the "dynalink_loader.h".
Please, review my description about this special case at: http://trac.ffmpeg.org/ticket/6405

So, this patch simplifies a lot the use of the libnpp functions (like the 'scale_npp').
More or less, is similar to the use of "nvenc_*" in FFmpeg. By default it doesn't link dynamic with CUDA, as the "dynalink_loader.h" has the code to load the functions from the shared library provided by the DRIVER, not the CUDA lib (the shared object "libcuda.so.1" is provided by the DRIVER, and not by the SDK).
In fact, the CUDA shared library is a mere wrapper to load some functions. These functions can be in shared objects or in static libraries.
Then, if you like to compile a regular FFmpeg with shared objects and dependent to the NVidia DRIVER, but not with the CUDA SDK, you can use this patch.

I hope you agree this explanation. This patch is really useful.
Regards,
A.H.

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-------- Original Message --------
Subject: Re: [FFmpeg-devel] [PATCH] configure: support static libnpp [v2]
Local Time: June 2, 2017 11:04 AM
UTC Time: June 2, 2017 9:04 AM
From: h.leppkes at gmail.com
To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>

On Fri, Jun 2, 2017 at 10:56 AM, Andreas Håkon
<andreas.hakon at protonmail.com> wrote:
> Hi,
>
> This patch is based on the original work done by Timo Rothenpieler, and his patch for static linking with libnpp:
> [http://ffmpeg.org/pipermail/ffmpeg-devel/2016-June/195078.html](https://ffmpeg.org/pipermail/ffmpeg-devel/2016-June/195078.html)
>
> Based in my recomendations now it's possible to link directly to libnpp* libraries without linking to the CUDA SDK:
> [http://trac.ffmpeg.org/ticket/6405](https://trac.ffmpeg.org/ticket/6405)
> http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=2d978d1c721ae69a9007b530153067736d4ddc79
>
> Then I created an updated version of the patch.
>
> By default the linking is the regular dynamic link (aka "--disable-libnpp-static" config).
> However, if you like to compile statically with "libnpp*_static.a" then add these parameters:
> $ configure ... --enable-nonfree --enable-libnpp --enable-libnpp-static --enable-cuda --extra-cflags="-I/usr/local/cuda/include/" --extra-ldflags="-L/usr/local/cuda/lib64/"
>
> This assumes the CUDA SDK is installed in "/usr/local/cuda".

I don't like that there is a separate configure option. We can link to
other libraries dynamically or statically depending on what is found,
without needing two configure options per library.

- Hendrik
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