Differences

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--- ffmpeg:video_resize [2025/01/12 12:28] – peter
+++ ffmpeg:video_resize [2025/01/12 13:32] (current) – removed peter
@@ Line 1: / Line 1: @@
-====== ffmpeg - Video resize ======
-<code bash>
--vf scale=width:height
-</code>
-----
-<code bash>
--vf scale=1280:-2
-</code>
-<WRAP info>
-**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.
-</WRAP>
-----
-===== Upscaling Video to 1080p =====
-<code bash>
-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
-</code>
-<WRAP info>
-**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.
-</WRAP>
-----
-===== Upscaling Video to 4K =====
-<code bash>
-ffmpeg -i input.mp4 -vf scale=3840x2560:flags=lanczos -c:v libx264 -preset slow -crf 21 output_compress_4k.mp4
-</code>
-----
-===== Downscaling Video =====
-<code bash>
-ffmpeg -i input.mp4 -vf scale=640x480:flags=lanczos -c:v libx264 -preset slow -crf 21 output_compress_480p.mp4
-</code>
-----
-===== Downscale or Downsize =====
-<code bash>
-ffmpeg -i input.mp4 -vf scale=1920:1080 -c:v libx264 smaller.mp4
-</code>
-----
-===== References =====
-https://ffmpeg.org/ffmpeg-filters.html#scale
-https://write.corbpie.com/upscaling-and-downscaling-video-with-ffmpeg/
-https://trac.ffmpeg.org/wiki/Scaling
-https://write.corbpie.com/a-guide-to-upscaling-or-downscaling-video-with-ffmpeg/
-https://superuser.com/questions/547296/resizing-videos-with-ffmpeg-avconv-to-fit-into-static-sized-player/1136305#1136305
-https://en.wikipedia.org/wiki/Lanczos_resampling