@eamon I guess ffprobe should help https://ffmpeg.org/ffprobe.html
@nicolaromano also, my poor old laptop shut itself down when I tried to do this because it overheated. I wish I knew how to, like, underclock a single process. Maybe renice it all the way down?
@nicolaromano thanks for pointing this out to me! If nothing else, I feel like easily extracting the bitrate will prove useful.
FWIW, I'm finding a lot of H.265 videos but my Roku's DLNA player can only decode H.264. Unless I find a better solution, I'll probably just target the same approximate bitrate and accept a minor loss in quality.