Ubuntu – How to add text to an animated .gif in gimp

ffmpeg 3.4.4 can do it directly on Ubuntu 18.04

You likely want to use something like:

sudo apt install ffmpeg
wget -O opengl-rotating-triangle.mp4 https://github.com/cirosantilli/media/blob/master/opengl-rotating-triangle.mp4?raw=true
ffmpeg \
  -i opengl-rotating-triangle.mp4 \
  -r 15 \
  -vf scale=512:-1 \
  -ss 00:00:03 -to 00:00:06 \
  opengl-rotating-triangle.gif

opengl-rotating-triangle.gif

Image info: 426kB, 45 frames, 512x512 apparent size, coalesced, conversion time on a Lenovo P51: 0.5s.

The above conversion also worked after a ulimit -Sv 1000000 (DRAM usage limited to 1GB), so it does "not consume huge amounts of memory" like previous attempts I did with Imagemagick which almost killed my machine. 500MB however failed because ffmpeg failed to load its shared libraries... time to upgrade your RAM ;-)?

Test data generation procedure described on this post.

The output has a visible dotting pattern, which is not as visible in "ffmpeg + convert" method below. We can try to improve the image quality with methods described at:

• https://superuser.com/questions/556029/how-do-i-convert-a-video-to-gif-using-ffmpeg-with-reasonable-quality
• https://stackoverflow.com/questions/42980663/ffmpeg-high-quality-animated-gif

E.g. using the palettegen filter:

ffmpeg \
  -i opengl-rotating-triangle.mp4 \
  -r 15 \
  -vf "scale=512:-1,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" \
  -ss 00:00:03 -to 00:00:06 \
  opengl-rotating-triangle-palettegen.gif

opengl-rotating-triangle-palettegen.gif

Image info: 979K, 45 frames, 512x512 apparent size, coalesced, conversion time on a Lenovo P51: 3.5s.

So we see that:

• the dotting pattern is much less visible now
• GIF size roughly doubled. TODO: why does simply choosing a palette increase the image size? Is it because now more colors so we need more bits per color? How to observe each palette?
• generation time was 7x slower, presumably because ffmpeg is first scanning through the entire video to determine an optimal palette

We could also play with documented palettegen parameters like palettegen=max_colors=16 to achieve different size quality trade-off points.

Argument breakdown

• -ss 00:00:03 -to 00:00:06: start and end time to cut the video from.

  No, GIFs are not the best way to pirate distribute videos online.

  See also: https://stackoverflow.com/questions/18444194/cutting-the-videos-based-on-start-and-end-time-using-ffmpeg

• -vf scale=512:-1: make the output 512 pixels in height, and adjust width to maintain the aspect ratio.

  This is a common use case for images for the web, which tend to have much smaller resolution than video.

  If you remove this option, the output GIF has the same height as the input video.

  The original video height can be found for example with ffprobe: https://superuser.com/questions/595177/how-to-retrieve-video-file-information-from-command-line-under-linux/1035178#1035178 and is 1024 x 1024 in our case.

• -r 15: sampling FPS.

  For example, the original video was 30 FPS, so -r 15 means that ffmpeg will pick one frame in every 2 (= 30 / 15).

  The perceived output FPS is adjusted to match the input however, so you won't notice a speedup, only greater granularity.

  The input FPS can be found with ffprobe, and the total number of input frames can be found with mediainfo as explained at: https://superuser.com/questions/84631/how-do-i-get-the-number-of-frames-in-a-video-on-the-linux-command-line/1044894#1044894

  I recommend this option because video formats usually have a higher framerate due to the larger resolution. With smaller GIFs, the lower framerate is less noticeable, and so we can skip some frames and make smaller GIFs.

Video camera footage example

If you want to see the result quality of a video camera video from Wikimedia Commons with a similar command:

wget https://upload.wikimedia.org/wikipedia/commons/f/f9/STS-132_Liftoff_Space_Shuttle_Atlantis.ogv
ffmpeg -i STS-132_Liftoff_Space_Shuttle_Atlantis.ogv -r 15 -vf scale=512:-1 \
  -ss 00:00:17 -to 00:00:22 STS-132_Liftoff_Space_Shuttle_Atlantis.gif

STS-132_Liftoff_Space_Shuttle_Atlantis.gif

Image info: 1.3MB, 75 frames, 512x288 apparent size, coalesced (has minimal effect however, because footage pans slightly from the start), conversion time on a Lenovo P51: 2.3s.

Here is a version with palettegen but only 2 seconds to fit the 2MiB upload limit:

Image info: 1.5MB, 30 frames, 512x288 apparent size, conversion time on a Lenovo P51: 43s.

A more direct:

sudo apt-get install ffmpeg
ffmpeg -i in.mp4 out.gif

also works, but the output GIF would be way larger than the input video, because video formats can compress more efficiently across frames with advanced algorithms, while GIF can only does a simple rectangular frame diff.

Before pre 18.04: ffmpeg + convert one-liner without intermediate files

ffmpeg could not handle GIF previously. The best I had was something along:

sudo apt-get install ffmpeg imagemagick
ffmpeg -i opengl-rotating-triangle.mp4 -r 15 -vf scale=512:-1 \
  -ss 00:00:03 -to 00:00:06 -f image2pipe -vcodec ppm - |
  convert -deconstruct -delay 5 -loop 0 - opengl-rotating-triangle-image-magick.gif

opengl-rotating-triangle-image-magick.gif

Image info: 995kB, 45 frames, 512x512 apparent size, coalesced.

For the Atlantis shuttle footage, and analogous:

ffmpeg -i STS-132_Liftoff_Space_Shuttle_Atlantis.ogv -r 15 -vf scale=512:-1 \
  -ss 00:00:17 -to 00:00:22 -f image2pipe -vcodec ppm - |
  convert -deconstruct -delay 5 -loop 0 - STS-132_Liftoff_Space_Shuttle_Atlantis_512x.gif

produced better looking output, but the final GIF was considerably larger at 6.2MB, so I can't upload it.

Explanation of some of the arguments:

• -loop 0: add the Netscape Gif extension Loop count field to the output. 0 means infinite loop as described at: http://www.vurdalakov.net/misc/gif/netscape-looping-application-extension eog, firefox and chromium all loop infinitely by default even without it, so I'm not sure how necessary it is anymore.

• -delay 5: time waited before showing the next frame, in hundreths of second, as described at: https://en.wikipedia.org/wiki/GIF#Animated_GIF byte 324. So 100 means 1 FPS, 5 means 1 / 0.5 == 20FPS.

• -deconstruct: compress across frames with rectangular diffs, see also: how can I resize an animated GIF file using ImageMagick?

Even if you reduce the height and framerate, the output GIF may still be larger than the video, since "real" non-GIF video formats compress across frames, while GIF only compresses individual frames.

A direct:

convert input.mp4 rpi2-bare-metal-blink.gif

worked, but almost killed my computer because of memory overflow, and produced an ouptput 100x larger for my 2s 1Mb input file. Maybe one day ImageMagick will catch up.

See also: https://superuser.com/questions/556029/how-do-i-convert-a-video-to-gif-using-ffmpeg-with-reasonable-quality

Tested on Ubuntu 17.10.

Gifski

https://gif.ski/

This is another option that was brought to my attention and which claims intelligent algorithms, so let's try it out.

First we need to convert the video to a sequence of images, and then feed that into gifsky, e.g.:

sudo snap install gifski
mkdir -p frames
ffmpeg \
  -i opengl-rotating-triangle.mp4 \
  -r 15 \
  -vf scale=512:-1 \
  -ss 00:00:03 -to 00:00:06 \
  frames/%04d.png
gifski -o opengl-rotating-triangle-gifski.gif frames/*.png

opengl-rotating-triangle-gifski.gif

Image info: 954K, 45 frames, 512x512 apparent size, not coalesced, conversion time on a Lenovo P51: 4.8s.

And the 2s STS:

Image info: 1.6M, 30 frames, 512x288 apparent size, not coalesced, conversion time on a Lenovo P51: 2.8s.

So for me, subjectively, this did not appear to offer significant benefit over ffmpeg's palettegen.

There are multiple ways to do this.

Option 1: Use a command line tool called gifsicle. It's available in default Ubuntu/Debian repositories.

It's fast and won't affect the quality, buy it only accepts frame numbers, not time, so if you need to cut exact time, you should figure out the frame number yourself. You can view the total number of frames and delay times between each frame with this command:

gifsicle --info YOURFILE.gif

Then you can divide the time you want to cut with the frame delay and it will give you the number of frames in this time, so you can figure out start frame and end frame.

Replace XXXX with the frame where you want your GIF to start, and YYYY with frame where you want your GIF to end.

gifsicle YOURFILE.gif '#XXXX-YYYYY' -O3 > cut.gif

Option 2: Using FFMPEG. It's also available in apt.

FFMPEG accepts time directly, so it's very straightforward, but it may worsen the quality of output gif and increase file size in some cases.

ffmpeg -i YOURFILE.gif -ss 00:00:04 -t 00:00:08 -async 1 cut.gif

Option 3: if you're ok with online tools and your GIF does not exceed 20MB, this online tool can cut GIFs by frame number or by time and won't affect the quality.