eac3 -b:a 448k : Compresses the 5.1 surround sound environment into highly compatible Dolby Digital Plus. 2. AV1 Modern Archival Compress (4K / 1080p)

libopus -b:a 256k : Encodes the multichannel audio track via the Opus codec for transparent fidelity at lower bitrates.

ffmpeg -i The.Pitt.S01E14.mkv -map 0:s:0 -c copy subs.sup

for f in The.Pitt.S01E*.mkv; do ffmpeg -i "$f" -c:v libx265 -crf 22 -preset medium \ -c:a aac -b:a 128k \ "$f%.mkv.hevc.mp4" done