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How do I resize a video to make it smaller with FFmpeg? (e.g. from 1024x576 to 720x480.)

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The most basic example is this:

ffmpeg -i input.avi -s 720x480 -c:a copy output.mkv

Using the scale filter will provide more flexibility:

ffmpeg -i input.avi -filter:v scale=720:-1 -c:a copy output.mkv

The -1 will tell ffmpeg to automatically choose the correct height in relation to the provided width to preserve the aspect ratio. -1 can also be used for width if you provide a given height.

One downside of scale when using libx264 is that this encoder requires even values and scale may automatically choose an odd value resulting in an error: width or height not divisible by 2. You can tell scale to choose an even value for a given height (720 in this example):

scale="trunc(oh*a/2)*2:720"

...or a given width (1280 in this example):

scale="1280:trunc(ow/a/2)*2"

Note that your ffmpeg build could complain about not recognizing -c or -filter options. It also may not support scale. In that case you should use a newer ffmpeg, which you can download as a static build, or compile yourself.

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    I tried ffmpeg -i output.mkv -filter:v scale=720:-1 -acodec copy -threads 12 output_shrink.mkv (in ffmpeg version 0.8.6-6:0.8.6-0ubuntu0.12.10.1) but got the error Unrecognized option 'filter:v'
    – doug65536
    Apr 26, 2013 at 15:41
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    After digging through the man page for ffmpeg several times I found that instead of -filter:v, the option appears to have been changed to -vf.
    – doug65536
    Apr 26, 2013 at 15:51
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    @doug65536 -filter:v and -vf are both fine. The Ubuntu version you were using is broken and outdated—it's not really FFmpeg's ffmpeg, but the binary supplied by Libav (the FFmpeg fork) under the same name.
    – slhck
    Jul 26, 2013 at 6:41
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    '-c' is short for -codec, ':a' specifies audio stream(s), 'copy' specifies the copy codec, which copies the stream(s) (in this case audio) without reencoding. Basically the audio streams will pass through. This is common when you are only manipulating the video stream.
    – jimhark
    Feb 5, 2016 at 23:27
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    You can tell scale to provide even value by using scale=720:-2
    – Barafu Albino
    May 30, 2018 at 17:38
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I use following commands to do rescaling for videos and images. For fixed width and height -

ffmpeg -i input.avi -vf scale="720:480" output.avi

and if you want to retain aspect ratio just give height as -1 and it will automatically resize based on the width -

ffmpeg -i input.avi -vf scale="720:-1" output.avi

If you want to scale based on input size e.g. lets say reduce the width/height to half you can do -

ffmpeg -i input.avi -vf scale="iw/2:ih/2" output.avi

NOTE :

iw : input width
ih : input height

Static build can be downloaded from - https://johnvansickle.com/ffmpeg/

Documentation : https://ffmpeg.org/ffmpeg.html#filter_005foption

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  • Not working. Stuck at handler_name : Sound Handle
    – Rushi M Thakker
    Aug 29, 2019 at 5:17
  • I got a terrible video quality with this command. Much better if I create output.mp4, not avi. So extension matters.
    – sekrett
    Oct 4, 2019 at 20:12
  • lol it doesn't work because "width not divisible by 2"
    – Alexey Sh.
    Dec 22, 2022 at 20:03

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