[FFmpeg-user] ffplay not found

[Moritz Barsnick]

On Sat, Oct 11, 2014 at 07:01:35 +0000, Carl Eugen Hoyos wrote:
> Concerning "--enable-ffplay": I just like to add that 
> this should not be part of any sane configure line, it 
> does NOT do what most people expect, ffplay is built 
> if libsdl-devel is installed.

BTW, this is somewhat different from what I expect from my experience
with autoconf based configure scripts. Note that this is possibly a
matter of taste, and that autoconf based scripts may differ in their
behavior as well.

This is what seems logical to me:
- Say nothing about a feature. The configure script decides what is
  default, and what to do if something can't be fulfilled (like to omit
  a feature).
- --disable-feature: Whatever the default is, don't include this, and
  don't error out if its (unique) dependencies aren't fulfilled.
- --enable-feature: Whatever the default is, try to include this, and
  error out if it can't be fulfilled.

ffmpeg's configure behaves differently. "--enable-ffplay" will just
confirm the default behavior, but still silently not build ffplay.
Well, not so silently, as the missing of SDL is reported (and probably
the resulting missing of ffplay). But this gets lost in all the
messages, and configure still creates its Makefile(s).

The same with enabling e.g. the filters that require font libraries. I
believe if you figure out that you're missing drawtext, then rebuild
with "--enable-filter=drawtext", you still won't get it if you're
missing freetype-devel.

I realize this is or may be a design decision regarding configure. I
just want to point it out, as it seems a bit confusing to me. I have
explicitly tripped over both of these issues. ;-)

Cheers,
Moritz