The VLC player [videolan[.]org] has for a very long time included capabilities that go beyond simply playing media files, but many of these features aren't the easiest to use, so they're not talked about all that much, & many people are not aware they exist. This is more-or-less a reminder that they're there, & are usually worth at least a quick look when you want to do something with media files but are unsure how best to do it. The ability to convert video files is an example.
In my case I just wanted to take the audio & video out of one kind of container & put it in another -- it did just what I wanted faster than the few alternative apps I found -- though VLC can do stuff like re-encode audio/video if you need it to. Just go to the Media Menu & click Convert / Save.
My story...
My wife works some evenings, which means she occasionally misses one or two of the TV series she likes to watch. Some are available on demand, some are online at either the network's site or Amazon, but one network delays it for a week unless you subscribe to their web service. It's also one of the main broadcast channels, meaning it has free, over the air digital broadcasts that aren't encrypted, & their programming is trivial to save if you have a TV tuner card or USB adapter. You just save [write to disk] the same file they broadcast [or stream if using cable].
I'm also lazy... I use Windows 7 Media Center to record the network's shows -- it's not a big deal to install an alternative app, but WMC is already right there & it works, albeit with a few minor problems. I can copy the recorded video file to the miniPC running 10, then use PowerDVD 16 Ultra for playback to the 4k TV, and it looks great.
Unfortunately PowerDVD does not display the embedded captioning, which for us is just an inconvenience, since it's her show, & I'm the one that needs CC or subs. SO I looked for a quick & easy way to get Captioning working -- since it's just an inconvenience, anything more than very quick & easy wouldn't be worth it to me.
CCExtractor can, as the name says, extract the embedded Captioning to a text file, which will work with PowerDVD [& many other players] but it won't touch .wtv files. The solution was to take the contents out of the .wtv container & put them in a standard video file format that CCExtractor would work with -- converters won't work because re-encoding abandons the CC embedded by the broadcast network. VLC did the job in just a couple of minutes, plus then a minute or so for CCExtractor to do it's thing. Works.
Saving a video to another type of container in VLC like this might also be useful with other videos in somewhat non-standard formats, e.g. Flash's .flv -- why spend the extra time & effort to re-encode if you don't have to?