[FFmpeg-user] --extra-ldflags not working

[Aaron Boxer]

On Sun, Mar 27, 2016 at 2:46 PM, Reindl Harald <h.reindl at thelounge.net>
wrote:

>
>
> Am 27.03.2016 um 15:53 schrieb Aaron Boxer:
>
>> On Sun, Mar 27, 2016 at 9:33 AM, Reindl Harald <h.reindl at thelounge.net>
>> wrote:
>>
>>
>>>
>>> Am 27.03.2016 um 15:23 schrieb Aaron Boxer:
>>>
>>> Dear List,
>>>> I am still troubleshooting linking to a local build of openjpeg.
>>>>
>>>> This is a static build of openjpeg, and the library  libopenjp2.a
>>>> is placed in the /usr/local/lib folder.
>>>>
>>>> (I am on Ubuntu)
>>>>
>>>> My configure command is:
>>>>
>>>> . $ ./configure --enable-libopenjpeg
>>>> --extra_cflags="-DHAVE_OPEN_OPENJPEG_2_1_OPENJPEG_H"
>>>> --extra-ldflags="-L/usr/local/lib"
>>>>
>>>> But this fails with a "libopenjpeg not found" error
>>>>
>>>>
>>> .a files are for static linking
>>> .so files are for dynamic linking
>>>
>>
>> --enable-static --extra-cflags='-I/usr/local/x264'
>>> --extra-ldflags='-I/usr/local/x264 -L/usr/local/x264 -ldl'
>>>
>>> Thanks, but linking is not the problem. The problem is locating the .a
>> file.
>> I did try --enable static, but doesn't help
>>
>
> what about read the other parts of my reply?
>


Ahhh, sorry, missed that one.   That will really help me, because i would
rather link to the shared
version, rather than the static.

So, I tried adding  -ldl,
but when I look in config.log, I see

/usr/local/lib/libopenjp2.so Undefined reference to `dlopen`
/usr/local/lib/libopenjp2.so Undefined reference to `dlclose`


Now, my library uses the dlopen and dlclose system calls to load another
shared library.

So, it looks like I need to tell configure to link to the system library
that has the dlopen and dlclose symbols.

Aaron





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