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To take a static screenshot of a selected part of my screen, I often use scrot with -s shot.png. This is great for adding illustrations to StackExchange posts. I even found this script to automatically upload such a screenshot to Imgur.com and put a link in my X clipboard!

Let's turn this up to twelve: How do I similarly create a GIF screencast?

There are programs like recordmydesktop, byzanz & co as discussed on Ask Ubuntu that aim to be "user friendly", but in my experience are buggy, inefficient, mostly unscriptable and unsuited for little one-off things like this.

I just want to select an area and record a GIF, with a console command I can understand, not some arcane unscriptable GUI monstrosity.

How can I do this?

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1  
Related: How to create animated GIF images of a screencast? from Ask Ubuntu. –  Cristian Ciupitu Oct 20 at 12:36

2 Answers 2

up vote 24 down vote accepted

OK then

GIF vimcast!

I started ffcast, did vim, quit ffcast, then converted .avi.gif.

I ran the recording commands in another terminal. Polished script for your $PATH at the end of this answer.

What happened?

Capturing

FFcast helps the user interactively select a screen region and hands over the geometry to an external command, such as FFmpeg, for screen recording.

ffcast is the glorious product of some hacking at the Arch Linux community (mainly lolilolicon). You can find it on github (or in the AUR for Archers). Its dependency list is just bash and ffmpeg, though you'll want xrectsel (AUR link) for interactive rectangle selection.

You can also append ffmpeg flags right after the command. I set -r 15 to capture at 15 frames per second and -codec:v huffyuv for lossless recording. (Play with these to tweak the size/quality tradeoff.)

GIFfing

ImageMagick can read .avi videos and has some GIF optimisation tricks that drastically reduce file size while preserving quality: The -layers Optimize to convert invokes the general-purpose optimiser. The ImageMagick manual has a page on advanced optimisations too.

Final script

This is what I have in my $PATH. It records into a temporary file before converting.

#!/bin/bash
TMP_AVI=$(mktemp /tmp/outXXXXXXXXXX.avi)
ffcast -s % ffmpeg -y -f x11grab -show_region 1 -framerate 15 \
    -video_size %s -i %D+%c -codec:v huffyuv                  \
    -vf crop="iw-mod(iw\\,2):ih-mod(ih\\,2)" $TMP_AVI         \
&& convert -set delay 10 -layers Optimize $TMP_AVI out.gif

(Thanks to BenC for detective work in figuring out the correct command after the recent ffcast update.)

Wheeeeee!

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This is really cool. Thanks for sharing. –  WhiteHotLoveTiger Feb 5 at 18:35
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I've created a version who doesn't require bash, but who works on any POSIX compliant shell github.com/chilicuil/ffcast –  chilicuil Mar 22 at 4:31
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Looks like the command line syntax of ffcast has changed: github.com/lolilolicon/FFcast/issues/8 –  Jack O'Connor Sep 30 at 20:25
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The simplest way to do it is now ffcast -s rec [filename], though that doesn't give the exact settings you're using in your example. Unfortunately, to give exact settings, you now have to give the entire ffmpeg command. Your call about the best way to update this answer :) –  Jack O'Connor Oct 1 at 1:47
4  
Based on the comments on GH, ffcast -s % ffmpeg -f x11grab -show_region 1 -framerate 20 -video_size %s -i %D+%c -codec:v huffyuv -vf crop="iw-mod(iw\\,2):ih-mod(ih\\,2)" $TMP_AVI seems to do the trick. –  BenC Oct 1 at 10:35

For me, the answer was to use ffcast with ffmpeg like so:

ffcast -w % ffmpeg -f x11grab -show_region 1 -framerate 20 -video_size %s -i %D+%c -codec:v huffyuv -vf crop="iw-mod(iw\\,2):ih-mod(ih\\,2)" out.avi

I then used ffmpeg to do the conversion from avi to gif - it's very fast and it keeps the framerate intact:

ffmpeg -i out.avi -pix_fmt rgb24 out.gif

Lastly I used convert in the same way as @anko's answer to optimise the gif, but I set a limit on resource usage to stop convert exiting with a killed message, and I removed the delay as ffmpeg has already handled that:

convert -limit memory 1 -limit map 1 -layers Optimize out.gif out_optimised.gif
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