Likely audacity-2.0.5-2.fc20.i586.rpm doesn't exist in any public RPM repository. You might want to check out
http://audacity.sourceforge.net/ if you haven't already done so. Since later program versions in general tend to be more demanding and thus have more RPM dependency requirements, I suspect that your best choice is to go with the earliest version >= 1.3.12 that has ffmpeg support compiled in.
smart-config-1.3.1-66.el6.x86_64.rpm is the worse setback. Possibly the same place that you got smart-1.3.1-66.el6.x86_64.rpm from also has smart-config-1.3.1-66.el6.x86_64.rpm. When I was deciding which version of smart to use on my SUSE 10.3 linux, I also had similar trouble with smart-1.2.X and ultimately went with smart-0.51-56.