====== Video encoding (ffmpeg) commands and explanations ======

===== Compress video stream =====

Compression without important video quality loss (tested with relatively low quality full HD source):\\
''$ ffmpeg -i input -vcodec libx265 -crf 24 output''\\
=> -crf is the compression factor. Lower is better, 24 is about as low as is useful for libx265\\
=> -map 0 to keep all streams (audio, subtitles, but also video)\\
=> Use -vf scale=-1:720 to resize to 720p (keeping aspect ratio with -1, resulting in calculation of width)\\

===== Select language streams =====

Do not re-encode streams, keep all subtitles and select English and French audio languages:\\
''$ ffmpeg -i input -map 0:v -map 0:s -map 0:m:language:eng -map 0:m:language:fre? -c copy output''\\
=> -c copy to avoid re-encoding streams\\
=> -map:0:v to keep all video streams\\
=> -map 0:s to keel all subtitle streams\\
=> -map 0:m:language:eng to keep streams with english metadata defined (all types of streams but impacting only audio (a) since we're keeping all subtitles in this case)\\
=> the ? at the end of -map instruction avoids failure if the matching input is missing\\

===== Script examples =====