[FFmpeg-devel] [PATCH] libx264: support for BUILD >= 63

[Aurelien Jacobs]

Stefano Sabatini wrote:

> On date Wednesday 2008-09-17 13:24:03 +0200, Frans de Boer encoded:
> > On Wed, 2008-09-17 at 13:01 +0200, Dominik 'Rathann' Mierzejewski wrote:
> > > On Wednesday, 17 September 2008 at 12:29, M?ns Rullg?rd wrote:
> > > > 
> > > > Stefano Sabatini wrote:
> > > > > On date Tuesday 2008-09-16 23:52:50 +0100, M?ns Rullg?rd encoded:
> > > > >> Stefano Sabatini <stefano.sabatini-lala at poste.it> writes:
> > > > >>
> > > > >> > On date Tuesday 2008-09-16 11:28:56 +0200, Stefano Sabatini encoded:
> > > > >> >> On date Tuesday 2008-09-16 09:24:40 +0100, M?ns Rullg?rd encoded:
> > > > >> >> > Stefano Sabatini <stefano.sabatini-lala at poste.it> writes:
> > > > >> > [...]
> > > > >> >> > It's always been expected that uses should have a recent version of
> > > > >> >> > libraries they build FFmpeg against.  Testing every little thing would
> > > > >> >> > become such a chore.
> > > > >> >>
> > > > >> >> We know which version we need, and a simple check in the configure
> > > > >> >> should ensure that the user is compiling against it.
> > > > >> >>
> > > > >> >> > > And while we're at it we could assert(X264_BUILD == x264_build()) in
> > > > >> >> > > the init code (assuming that function is implemented).
> > > > >> >> >
> > > > >> >> > It a little harsh with assert(), wouldn't you say?  In fact, this
> > > > >> >> > shouldn't be needed at all, assuming libx264 uses correct shared
> > > > >> >> > library versioning.
> > > > >> >>
> > > > >> >> See my other mail in response to Dark Shikari, but I have not a strong
> > > > >> >> opinion on this, the configure check may be sufficient.
> > > > >> >
> > > > >> > Attached there is a first experiment with check_version.
> > > > > [...]
> > > > >> Rejected.  It doesn't work if cross-compiling.  It may have other
> > > > >> faults too; I didn't check carefully.  Besides, I don't think this
> > > > >> check is necessary.
> > > > >
> > > > > Would be a solution using pkg-config acceptable?
> > > > 
> > > > No.  pkg-config only leads to misery.  Did you know that every time
> > > > someone uses pkg-config, a child in Africa dies?
> > > 
> > > Don't be ridiculous. I'm sure a solution using pkg-config with a fallback
> > > to some other method if pkg-config is not available is acceptable.

If we have a clean fallback to some other method, we don't need the
pkg-config method anymore...

> [...]
> The only alternative I can see for detecting the header version is to
> grep the 264.h header, which leads to a very ad-hoc solution, or not
> to support the version check at all, [...]

Maybe something as simple as doing a check_cpp on the following code:

#include <x264.h>
#if X264_BUILD < 63
#error "outdated x264"
#endif

IIRC, #error is not standard, but I guess any compiler which don't
support it will just error out because of the unknown token, and
thus, will also have the desired effect in this specific case.

Aurel