ffmpeg -i input.mkv -vf "scale=1280:720" -c:v libx264 -crf 22 -preset medium -c:a aac -b:a 128k output_720p.mp4

Run:

ffmpeg -i cawd764engsub.mkv

Note: container, video codec (e.g., h264, hevc), audio codec, subtitle streams, resolution, frame rate, bitrates.

For many files, use a shell loop (bash):

for f in *.mkv; do
  ffmpeg -i "$f" -c:v libx264 -crf 22 -preset medium -c:a aac -b:a 128k "$f%.*.mp4"
done

Below is a detailed step-by-step guide to convert, compress, and produce an optimized MP4 with embedded English subtitles, suitable for web or mobile playback. Commands use ffmpeg (cross‑platform, free) and practical settings.