MP4 containers don't support all subtitle/codec combinations with HEVC.
MKV handles everything, so always output .mkv and remove the original
if it was a different format.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Resumable batch script that finds H.264 files, re-encodes to HEVC
(libx265 CRF 24), verifies duration, and replaces originals.
Tracks completed files in /var/lib/transcode-hevc/completed.log.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
