I'm not familiar with FFMPEG at all and would like to know how to convert MP4 to OGV format while still keeping the same video and audio quality?
Basic command is
ffmpeg -i input.mp4 -c:v libtheora -q:v 7 -c:a libvorbis -q:a 4 output.ogv
You'll have to fiddle with the q values for video and audio if the result's not acceptable. Lower values are better but produce bigger files.