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I have 2 GIFs that are the same length.

I want to put the GIFs beside each other to have 1 GIF with both playing at the same time. I have tried to use the convert tool with: 

convert +append 1.gif1 2.gif output.gif

However, this seems to blend all the images together and changes the size to be extremely small.

I was thinking that I could append each image together and then create a GIF out of those already combined images. However it did not work when I tried:

convert -delay 15 -loop 0 1*.png 2*.png +append output.gif

I have a lot of images with long names and I do not want to have to go through individually and append each figure with new naming conventions.

Kurt Pfeifle
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BenT
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1 Answers1

29

I don't have 2 animated GIFs of the same length, so I'll just use two copies of this one:

enter image description here

Let's look at the frames in there, with this:

identify 1.gif
1.gif[0] GIF 500x339 500x339+0+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[1] GIF 449x339 500x339+51+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[2] GIF 449x339 500x339+51+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[3] GIF 449x339 500x339+51+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[4] GIF 448x339 500x339+52+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[5] GIF 449x339 500x339+51+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[6] GIF 448x339 500x339+52+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[7] GIF 448x339 500x339+52+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[8] GIF 448x339 500x339+52+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[9] GIF 448x339 500x339+52+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[10] GIF 448x339 500x339+52+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[11] GIF 500x339 500x339+0+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[12] GIF 500x339 500x339+0+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[13] GIF 500x339 500x339+0+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[14] GIF 500x339 500x339+0+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[15] GIF 448x339 500x339+52+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[16] GIF 500x339 500x339+0+0 8-bit sRGB 32c 508KB 0.000u 0:00.000
1.gif[17] GIF 500x339 500x339+0+0 8-bit sRGB 32c 508KB 0.000u 0:00.000

Mmmm, 18 frames with different sizes, that means we need to use -coalesce to rebuild partial frames into full ones.

Let's copy that and make 2.gif

cp 1.gif 2.gif

Now we can split the two gifs into their component frames, like this:

convert 1.gif -coalesce a-%04d.gif     # split frames of 1.gif into a-0001.gif, a-0002.gif etc
convert 2.gif -coalesce b-%04d.gif     # split frames of 2.gif into b-0001.gif, b-0002.gif etc

Now let's join the individual frames side-by-side:

for f in a-*.gif; do convert $f ${f/a/b} +append $f; done

Note that ${f/a/b} is a bash-ism meaning "take the value of f and replace the letter 'a' with 'b'".

And put them back together again:

convert -loop 0 -delay 20 a-*.gif result.gif

That looks longer, and harder, than it is because I tried to explain it all, but it looks like this really:

convert 1.gif -coalesce a-%04d.gif                         # separate frames of 1.gif
convert 2.gif -coalesce b-%04d.gif                         # separate frames of 2.gif
for f in a-*.gif; do convert $f ${f/a/b} +append $f; done  # append frames side-by-side
convert -loop 0 -delay 20 a-*.gif result.gif               # rejoin frames

enter image description here

Note that this conceptual code, not production quality. It doesn't remove the temporary files it creates, nor does it carry the inter-frame time forward from the original GIFs. If you want to get the original frame rate you could get them like this and save them into an array and feed the delays back into the re-animation command at the end:

identify -format "%f[%s] %T\n" 1.gif
1.gif[0] 8
1.gif[1] 8
1.gif[2] 8
1.gif[3] 8
1.gif[4] 8
1.gif[5] 8
1.gif[6] 8
1.gif[7] 8
1.gif[8] 8
1.gif[9] 8
1.gif[10] 11
1.gif[11] 11
1.gif[12] 11
1.gif[13] 11
1.gif[14] 11
1.gif[15] 11
1.gif[16] 11
1.gif[17] 26

Also, you may want a spacer between the two animations, say 10 pixels, which you can do by replacing the convert command inside the for loop with this one:

convert $f -size 10x xc:none ${f/a/b} +append $f

enter image description here

Mark Setchell
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  • I am using ImageMagic (v7.0.2) and all of the commands work great, except for the `for f in a-*.gif; do convert $f ${f/a/b} +append $f; done` According to the documentation on the FOR loop, I have changed this to: `FOR %f in (a-*.gif); DO convert %f %{f/a/b} +append %f; done`, but I'm still having trouble. Any suggestions? The documentation on FOR loops I am using is here (http://www.imagemagick.org/Usage/windows/#for_loops), and the command for appending I am using is: (http://www.imagemagick.org/discourse-server/viewtopic.php?t=11320) – AaronJPung Nov 03 '16 at 17:13
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    The `${f/a/b}` means *"take `f` and replace all instances of `a` within it by `b`"* and is specific to `bash` (in Linux). You will need to find the Windows-y way to do that. – Mark Setchell Nov 03 '16 at 17:21
  • Thanks for confirming that. Yeah, I'd noticed the syntax difference from the links I included. I think in Windows, $ --> %. I'll keep at it. – AaronJPung Nov 03 '16 at 19:32
  • @MarkSetchell is there a way to make this process suitable for multi images ? I guess giving a label like a and b for each image would be difficult in that case. Let's say I want to merge all gifs in my current directory side by side. What should I do for that ? images are same length and all frames are equal size – zwlayer Feb 12 '17 at 11:21
  • You're not on Windows, hopefully? – Mark Setchell Feb 12 '17 at 11:43
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    Almost three years into the future and this is still the best solution i've found. Thank you! For comparison just doing "montage -tile 2x1 ..." (with identical dimensioned and nframes) and the result looks like crap (why?) – Theophrastus May 14 '18 at 23:06
  • To fix the issue with transparent GIFs, add `-dispose 2` to the last `convert`. It should go before `a-*.gif`. – user Jun 28 '19 at 10:04