About a year ago I wrote a zsh script to analyse files in my collection and format/selectively re-encode them based on a set of rules. Basically, I wanted .mp4 files that the Roku Plex app could play back without having to do any kind of re-encoding (stream/container or otherwise).<p>That started me on a 2-week mission of understanding the command-line. Good God is it a nightmare! All my script was doing was reading the existing file, deciding on the "correct" video and audio track, creating an AC-3 if only a DTS existed, and adding a two-channel AAC track. It would also re-encode the video track if the bitrate was too high or the profile was greater than the Roku could handle.<p>Here's the thing that I discovered, as much as I swore at the command-line interface, I couldn't come up with a more elegant solution that would still allow the application to be controlled entirely from the CLI. Ffmpeg is capable of <i>so much</i> that figuring out a way to just "tell it what to do" from a CLI ends up with an interface that's ... that difficult to use. The program, very nearly, handles <i>everything</i>[0] as it relates to media files and simplifying the application to improve the CLI would necessarily involve eliminating features. It's one of those cases where a light-weight DSL would provide a superior interface (and to a certain extent, the command-line of ffmpeg nearly qualifies as a DSL).<p>[0] The "very nearly" was necessary because of the <i>one</i> feature I found that it didn't handle. It's not possible in the current version to convert subtitle tracks from DVDs to a format that is "legal" in an mp4 file because the DVD subtitles are images rather than text, whereas the only formats that are legal for the mp4 container are text. I found some utilities that can handle this, but didn't try any, opting instead to simply download them when I encountered a file with subtitles in this format.