[FFmpeg-trac] #349(undetermined:open): MingW32 Cross Compile of FFMPEG Fails

FFmpeg trac at avcodec.org
Wed Jul 25 12:34:57 CEST 2012

#349: MingW32 Cross Compile of FFMPEG Fails
             Reporter:  jlsantiago0  |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:
              Version:  unspecified  |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0

Comment (by stump):

 I'm running into this problem too, on current git master.

 As an observation, libav switched to the `dlltool` line in
 [http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=ec10a9ab commit
 ec10a9ab] and ffmpeg later reverted that in
 [http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=85c9365d commit
 85c9365d], saying "this was requested by the windows experts / seems
 dlltool causes alot of problems".

 This makes me think that an import library output by `dlltool` will still
 be incompatible with MSVC. Last time I tried linking to a MinGW-generated
 implib with MSVC, bad things happened (I'm not currently in a position to

 To work around this, in the script from which I cross-build ffmpeg, I
 hackishly patch `library.mak` (will attach patch for reference) to ignore
 the error installing the `.lib` file, just as the failure to invoke
 `lib.exe` is already ignored during `make`. (I don't consider `make -k
 install` to be a satisfactory solution, as that could hide real problems.)
 It looks like the mechanism I'm modifying is intended to be more general,
 but it looks like it's not used for anything other than installing the
 MSVC-compatible implibs for a mingw32 build. I think that if this import
 library incompatibility still exists, the right thing to do is probably to
 just ignore the error during install (or condition installation on the
 file's pre-existence).

 (As another observation, if the binutils were indeed capable of making
 MSVC-compatible implibs, it would be possible to just pass `-Wl,--out-
 implib,foo.lib` while linking the DLLs and satisfy both MinGW and MSVC, as
 one of the expansions MinGW tries for `-lfoo` is `foo.lib`.)

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/349#comment:9>
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