ffmpeg:video:resize
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Table of Contents
ffmpeg - Video - Resize
-vf scale=width:height
-vf scale=1280:-2
NOTE:
- -1 for the width or height will keep it in ratio to the other specified dimension.
- -2 will keep it in ratio to the other specified dimension, but, to ensure it is divisible by 2 (a requirement for certain encodings such as yuv420p) the width or height will be adjusted if necessary.
Upscaling Video to 1080p
ffmpeg -i input.mp4 -vf scale=1920x1080:flags=lanczos -c:v libx264 -preset slow -crf 21 output_compress_1080p.mp4 # Using GPU. ffmpeg -vaapi_device /dev/dri/renderD128 -i "input.mkv" -vf 'hwupload,scale_vaapi=w=1920:h=1080:format=nv12' -map 0:v -metadata:s:v:0 language=eng -c:v hevc_vaapi -map 0:a -metadata:s:a:0 language=eng -map 0:s? -metadata:s:s:0 language=eng -rc_mode CQP -global_quality 25 -c:a copy -c:s copy -profile:v main -v verbose output_1080p.mkv
NOTE: Lanczos resampling involves a sinc filter as well.
- It is more computationally expensive but usually described as very high quality and can be used for up- and downsampling.
Upscaling Video to 4K
ffmpeg -i input.mp4 -vf scale=3840x2560:flags=lanczos -c:v libx264 -preset slow -crf 21 output_compress_4k.mp4
Faster
ffmpeg -i input.mp4 -vf scale=3840x2560:flags=lanczos -c:v libx264 -preset veryfast -crf 25 output.mp4
NOTE: To achieve a faster upscale use a fast preset like veryfast or superfast however these will give a poorer compression but will complete the upscaling faster.
- Using a CRF of 25 will also lower the output quality slightly (less bitrate = less size).
- Slower encoding means more quality is kept and the compression is superior.
Downscaling Video
ffmpeg -i input.mp4 -vf scale=640x480:flags=lanczos -c:v libx264 -preset slow -crf 21 output_compress_480p.mp4
Downscale or Downsize
ffmpeg -i input.mp4 -vf scale=1920:1080 -c:v libx264 smaller.mp4
References
ffmpeg/video/resize.1738188385.txt.gz · Last modified: 2025/01/29 22:06 by peter