ffmpeg

Get info only (encoding, etc)

ffmpeg -i input.avi

Convert to x264

ffmpeg -i input.mp4 -c:v libx264 output.mp4

Working convert for video/audio for Plex: MKV, x264, AAC, 8-bit

ffmpeg -i Andrei.avi -c:v libx264 -pix_fmt yuv420p -c:a aac -strict -2 Andrei.mkv

Convert .ass subtitles to .srt

ffmpeg -i subs.ass subs.srt

Adjust subtitle timing

(6.5 second adjustment)
ffmpeg -itsoffset 6.5 -i .\Fellowship.of.the.ring.srt -c copy .\Fellowship.of.the.ring.FIXED.srt