If you would like to scale your video using FFMPEG you can do this by Just using `-2`

From the FFMPEG scale filter documentation:

If one of the values is

`-n`

with`n > 1`

, the scale filter will also use a value that maintains the aspect ratio of the input image, calculated from the other specified dimension. After that it will, however, make sure that the calculated dimension is divisible by`n`

and adjust the value if necessary.

# Examples

Set width to 1280, and height will automatically be calculated to preserve the aspect ratio, **and** the height will be divisible by 2:

`-vf scale=1280:-2`

Same as above, but with a declared height instead; leaving width to be dealt with by the filter:

`-vf scale=-2:720`

# “divisible by 2”

As required by x264, the “divisible by 2 for width and height” is needed for YUV 4:2:0 chroma subsampled outputs. 4:2:2 would need “divisible by 2 for width”, and 4:4:4 does not have these restrictions. However, most non-FFmpeg based players can only properly decode 4:2:0, so that is why you often see `ffmpeg`

commands with the `-pix_fmt yuv420p`

option when outputting H.264 video.

# Caveat

Unfortunately you can’t use `-2`

for both width **and** height, but if you already specified one dimension then using `-2`

is a simple solution.

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