How can I add / mux cover art (JPEG, PNG..) to an OGM file. I have a series of these files which contain audio and video streams, and I would like to attach thumbnail photos. I have tried: 1) Appending an ID-3 tag. 2) mkvtoolnix to append the photo - but this alters the file format from OGG to Matroska. 3) Using the 'tagging' feature of foobar2000 - but foobar2000 states that the operation is not supported for the file type. 4) VirtualDubMod - I can open and save the OGM file but I cannot append an image. 5) VLC Player - I can edit metadata but I cannot commit the changes or even a picture. I have also Googled extensively. Help!