I have a bunch of .mkv files with diverse content, so I don't know about their audio, subtitle, chapter and attachment contents. Common denominator: They all have one video track.
I want to batch replace the video track only with a reencoded version of it, keeping the rest of the file with audio, subs, chapters and attachments intact. What is the easiest way to do this? Earlier questions always made assumptions about the other content of the file, so not really applicable - also, batch mode desired.
x264, ffmpeg or avconv can all be used if one of these is better for the job than the other.