[FFmpeg-user] Mingw builds of ffmpeg DLLs - how are exports chosen?

Aleste aleste7 at gmail.com
Sat Oct 29 01:19:52 CEST 2011



I've been building ffmpeg on Windows using mingw, and I have a question.


I'm trying to understand the mechanism that causes gcc to generate exports
in the various DLLs generated when I run make.  I was looking for
__declspec(dllexport) markups, but I saw none of those.  I then looked for a
.def file, and didn't see one in the source code either.


While a def file is generated during the build for each DLL, but by that
time the export list has already been determined.  I.e. the gcc -shared
-Wl,--output-def,libavformat/avformat-53.def command appears to generate the
def file for e.g. libavforma, as well as the DLL, obviously.


Now, what I was hoping to find out is where the authority is for which
symbols get exported on Windows and which not.  I thought I understood how
this worked in mingw, and evidently I don't.  :-)



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