>>106608751
in zstd\programs\fileio.c:
int FIO_compressFilename(FIO_ctx_t* const fCtx, FIO_prefs_t* const prefs, const char* dstFileName,
const char* srcFileName, const char* dictFileName,
int compressionLevel, ZSTD_compressionParameters comprParams)
and then:
int FIO_decompressFilename(FIO_ctx_t* const fCtx, FIO_prefs_t* const prefs,
const char* dstFileName, const char* srcFileName,
const char* dictFileName)
maybe compile and debug it with a breakpoint to see where it writes/reads compression level? seems like it's an int somewhere.