Foobar2000 Talk:Oggpreview

I don't understand how the explanation of this option: Use Replaygain: use replaygain information to create the preview. For more information about replaygain, see here:[[ Does it use existing replaygain info from source files or does calculate replaygain of the newly created files (this seems more appropriate)? Approximately what impact does it have on speed? Thank you for this great source of information. :)