the default compression level should be 0, which results in ZSTD_CLEVEL_DEFAULT

Author: gfx

ext/zstdruby/zstdruby.c

@@ -19,7 +19,7 @@ static VALUE compress(int argc, VALUE *argv, VALUE self)
 
   int compression_level;
   if (NIL_P(compression_level_value)) {
-    compression_level = 1;
+    compression_level = 0; // The default. See ZSTD_CLEVEL_DEFAULT in zstd_compress.c
   } else {
     Check_Type(compression_level_value, RUBY_T_FIXNUM);
     compression_level = FIX2INT(compression_level_value);