ffmpeg mingw compilation 8192 char limits

问题

I´m trying to compile ffmpeg shared with mingw64 on Windows 10. Here is the configure command:

./configure --arch=x86_64 --enable-shared --disable-static --prefix=/e/Downloads/ffmpeg-dyn/

Everything looks ok. Then I make:

mingw32-make.exe -j16

But I encounter this error:

LD      libswresample/swresample-3.dll
LD      libswscale/swscale-5.dll
dlltool -m i386:x86-64 -d libswresample/swresample-3.def -l libswresample/swresample.lib -D swresample-3.dll
dlltool -m i386:x86-64 -d libswscale/swscale-5.def -l libswscale/swscale.lib -D swscale-5.dll
STRIP   libavcodec/x86/vp9itxfm.o
GEN     libavcodec/libavcodec.ver
EXTERN_PREFIX="" AR="ar" NM="nm -g" ./compat/windows/makedef libavcodec/libavcodec.ver libavcodec/012v.o libavcodec/4xm.o libavcodec/8bps.o libavcodec/8svx.o libavcodec/a64multienc.o 
... // SKIP all .o files for stackoverflow
libavcodec/y41pdec.o libavcodec/y41penc.o libavcodec/ylc.o libavcodec/yop.o libavcodec/yuv4dec.o libavcodec/yuv4enc.o libavcodec/zerocodec.o libavcodec/zmbv.o libavcodec/zmbvenc.o > libavcodec/avcodec-58.def
Object does not exist: lib
mingw32-make: *** [ffbuild/library.mak:102: libavcodec/avcodec-58.dll] Error 1

As you can see Object does not exist: lib does not mean anything. After some investigations it looks like this is due to cmd.exe 8129 character limitation for parameters. I tried to set a different ComSpec value, without success. I also tried to do some changes in library.mak Using a file containing *.o files but I encounter many errors.

It looks like this is a known issue but nothing I tried works : https://trac.ffmpeg.org/ticket/6620

Any tips to fix it ?

回答1:

Thanks to Carl Eugen from ffmpeg-user mailing list.

I changed library.mak line 51

$(SUBDIR)$(SLIBNAME_WITH_MAJOR): $(OBJS) $(SLIBOBJS) $(SUBDIR)lib$(NAME).ver
EXTERN_PREFIX="$(EXTERN_PREFIX)" AR="$(AR_CMD)" NM="$(NM_CMD)" $(SRC_PATH)/compat/windows/makedef $(SUBDIR)lib$(NAME).ver $(SUBDIR)*.o > $$(@:$(SLIBSUF)=.def)
$$(LD) $(SHFLAGS) $(LDFLAGS) $(LDSOFLAGS) $$(LD_O) $$(filter %.o,$$^) $(FFEXTRALIBS)
$(SLIB_EXTRA_CMD)

And for each dll problems, use this :

$ mingw32-make.exe V=1 libavcodec/avcodec-58.dll

description: mingw32-make.exe V=1 subdirlib/libname.dll

Complete discussion with Carl Eugen available here : https://www.mail-archive.com/ffmpeg-user@ffmpeg.org/msg19801.html

来源：https://stackoverflow.com/questions/53852242/ffmpeg-mingw-compilation-8192-char-limits