Windows libs for ffmpeg don't link (visual studio)?

Question

So, I'm trying to get a project I'm writing to link against ffmpeg libraries but I keep getting linker errors:

1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "struct AVCodec * __cdecl avcodec_find_encoder(enum AVCodecID)" (?avcodec_find_encoder@@YAPEAUAVCodec@@W4AVCodecID@@@Z)
1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "int __cdecl av_dict_set(struct AVDictionary * *,char const *,char const *,int)" (?av_dict_set@@YAHPEAPEAUAVDictionary@@PEBD1H@Z)
1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "int __cdecl avcodec_encode_video(struct AVCodecContext *,unsigned char *,int,struct AVFrame const *)" (?avcodec_encode_video@@YAHPEAUAVCodecContext@@PEAEHPEBUAVFrame@@@Z)
1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "struct AVCodecContext * __cdecl avcodec_alloc_context3(struct AVCodec const *)" (?avcodec_alloc_context3@@YAPEAUAVCodecContext@@PEBUAVCodec@@@Z)
1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "struct AVFrame * __cdecl avcodec_alloc_frame(void)" (?avcodec_alloc_frame@@YAPEAUAVFrame@@XZ)
1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "void __cdecl av_free(void *)" (?av_free@@YAXPEAX@Z)
1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "int __cdecl avcodec_open2(struct AVCodecContext *,struct AVCodec const *,struct AVDictionary * *)" (?avcodec_open2@@YAHPEAUAVCodecContext@@PEBUAVCodec@@PEAPEAUAVDictionary@@@Z)
1>GLViewLASReader.obj : error LNK2001: unresolved external symbol "int __cdecl avcodec_close(struct AVCodecContext *)" (?avcodec_close@@YAHPEAUAVCodecContext@@@Z)
1>C:\STEAMiE\usr\modules\LASReader\win32\Release\LASReader.exe : fatal error LNK1120: 8 unresolved externals

I downloaded the dev package from:

http://ffmpeg.zeranoe.com/builds/

But when I link against the libs like I normally would, I get the linker errors. Is this package somehow different from every other library I've tried to use that I just need the .h/.libs for? Is there a reason why it has to be that way?

Answer 1

As there is no _ prefix at the function identifier in your linker error message, I suspect your forgot to put the ffmpeg include file you use in a ' extern "C" { }' section.