Is there an app that integrates muxing, demuxing and editing?

[dstarfire]

Like the title says, are there any apps that combine a muxer, demuxer, and some basic editing tools (I'm most interested in working with subtitles) into a single package, so I can edit a file without having to manually demux and then remux the files?

I'm thinking something like the way winrar lets me open a file in a .zip archive, edit it, and have the archive be automatically updated with the changed file.

I'd really like a free app, but I suspect this level of functionality (if it exists at all) will likely only be found in an expensive software suite.

[Baldrick]

I think you can use subtitle edit to open mkv and mp4s and edit the subs. But not save as same format again.