I have a file of resolution 3840x1632, but my TV stretches the picture vertically to fill up all 2160 pixels of height. Is it possible to use ffmpeg to add blank / black height, while preserving the video and audio quality?

Tried doing this, which seemed to work (took about 2 hours, the same length of the video), but greatly reduced the file size/video quality):

ffmpeg -i input.mkv -filter:v "pad=3840:2160:0:280" -c:a copy my_output_video.mkv

Is there a switch to say "keep everything else the same"?

Thank you!


You'll have to manually set encoding parameters.

ffmpeg -i input.mkv -filter:v "pad=3840:2160:0:280,setsar=1" -crf 18 -preset faster -c:a copy my_output_video.mkv

The CRF option sets the tradeoff for size/quality. Lower values produce better quality but larger files. The preset will increase speed, but for same quality, the file size will be larger.

The setsar filter has been added as a precaution in case your player reads the SAR stored in the file and stretches the video based on that value.

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