[FFmpeg-devel] [PATCH] libavcodec/makefile: prevent from installing disabled headers.

[Reimar Döffinger]

On 20.10.2014, at 10:40, Matt Oliver <protogonoi at gmail.com> wrote:
> FYI VDA and VDPAU etc. wont compile with mingw as the system headers
> (vdpau.h etc) are missing by default. Which is why these headers error on
> Windows as they include other headers that just are not available on that
> platform.

vdpau.h is not a system header (it is part of libvdpau), nor is it generally installed on Linux systems.
It probably wouldn't even be hard to hack e.g. libva-gl to instead use dxva and you'd have VDPAU on Windows.

> So disabling headers based on whether the config option is set is probably
> not the right way. But perhaps headers can be prevented from being
> installed on platforms that can just plain never use them.

None of the APIs I know of can't be made to work on other OSs if one had any reason to do so.

> Perhaps something like HEADERS-$(have_dxva_h) or based on the platform
> being compiled for.

Still leaves the question: what is the advantage?
In the end, and application wanting to use those headers has to test if they can be compiled regardless (as e.g. Linux might miss vdpau.h), so what is advantage of adding weird unpredictable special-cases to not install headers?