There are two problems when debugging projects written in ffmpeg with vs2015:

Question 1:

“LNK2019 unresolved external symbol __imp____iob_func reference in function _ShowError”

Solution: add this sentence to the source code: extern “C” {file _iob_func [3] = {* stdin, * stdout, * stderr};}

Question 2:

“unesolved external symbol _imp_fprintf referenced in funciton _showerror”

Solution: right-click the item — properties — configuration — linker — input — additional dependencies to add the library legacy_stdio_definitions.lib