"Could not locate MKV, AVI, MP4, WMV, FLAC or MP3 data in file"

*note: english is not my native lang, so it's problem to completly understand all tutorials and explain all details to you. don't judge me*
Hi there. I've been trying to convert .srs files into .flac or put it in .rar, I did all things in cmd, put all neccesary files in current folder, but some reason it doesn't worked. And always the same error: "Could not locate MKV, AVI, MP4, WMV, FLAC or MP3 data in file". I'll appreciate any help.