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Converting Video into Animated Images Using FFmpeg

faraixyz

Farai Gandiya

Posted on June 11, 2021

Converting Video into Animated Images Using FFmpeg

Converting Video into Animated Images Using FFmpeg was first published on Farai's Codelab.

This post has been republished with new information.

This post will supplement an upcoming post on why you should stop using GIFs in favor of newer image and video formats. Here’s how to generate animated images in various media formats using FFmpeg.

Preparing The Source Clip For Further Conversion

First thing to do is convert it to an uncompressed y4m video, slicing it up and setting the framerate as necessary:

ffmpeg -ss <start_point> -t <duration_from_start> -i <source_media> -an -vf 'scale=<width>:<height>,setpts=<stretch_factor>*PTS,fps=<framerate>' -pix_fmt yuv420p <raw_input>.y4m
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What the option flags mean:

Option Description
-ss Marks the start position of the video stream as a time duration
-t Specifies the duration of the datastream from -ss (or 0) as a time duration. Use both -ss and -t before -i to limit the video input.
-an Removes audio
-vf The video filters
scale Sets the w idth and h eight of the video
setpts Sets the presentation timestamps (PTS) for the video. Used to speed up and slow down video
fps Specifies the framerate for the video.
pix_fmt Sets the color format. Necessary if you’re converting from GIFs.

Note, if you are going to set a framerate for a GIF, it has a delay between frames in hundreths of a second (fps=100/delay). So:

Delay Framerate
1 10pfs
2 50fps
3 33fps
4 25fps
5 20fps
6 15fps

Images

GIF 

ffmpeg -i <source_input>.y4m -filter_complex "[0:v] split [a][b];[a] palettegen [p];[b][p] paletteuse" -loop 0 <output>.gif
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Simply put the -filter_complex flag in this case generates a color palette to use in the GIF. See GIPHY’s Engineering blog on how to make GIFs to explain the flag.

-loop 0 makes it loop forever.

You can leave it out, resulting in a much smaller GIF (at the expense of quality).

WebP 

ffmpeg -i <raw_input>.y4m -loop 0 -q:v 100 -compression_level 6 <output>.webp
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q:v is the image quality, from 0 to 100. It’ll be much smaller, but WebP can get blocky if you push the quality too hard.

Like GIF, -loop 0 makes it loop forever.

Sequenced AVIF (Chrome For Now)

ffmpeg doesn’t support writing to AVIF containers when I wrote this, so you nee to use avifenc to do this.

avifenc <raw_input>.y4m <output>.avif
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Videos

From here on out, I won’t go over the options too much since there’s a lot to consider, most of which I don’t understand so I’ll link to the respective encoding guide if you want more options.

AVC/h.264 MP4 (widest support) 

ffmpeg -i <raw_input>.y4m -c:v libx264 -preset veryslow <output>.mp4
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The preset flag tries to find the best tradeoff between quality and compression at a given bitrate and file size.

H.264 Encoding Guide

HEVC/h.265 (WebKit) 

ffmpeg -i <raw_input>.y4m -c:v libx265 -preset veryslow -tag:v hvc1 <output>.mp4
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You need the -tag:v hvc1 for the video to play in Safari. Thanks Aaron!.

preset is the same as in AVC.

H.265 Encoding Guide

VP8/VP9 (Not WebKit)

Switch the vp8 for vp9 depending on which one you choose. vp9 is newer so better, although it doesn’t have the support of vp8 (although it’s reasonable).

ffmpeg -i <raw_input>.y4m -c:v vp9 <output>.webm
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VP8 Encoding Guide/VP9 Encoding Guide

AV1 Video (Chrome and Firefox)

Update 21 May 2021: When I initially wrote this post, my build of ffmpeg didn’t include different av1 encoders so I tried to encode AV1 videos using the encoders directly. As I was updating this post to add instructions on how them, I noticed that the alternatate encoders are now built in the standard build of ffmpeg.

Encoding AV1 will use a lot of CPU and it takes longer than the others.

ffmpeg -i <raw_input>.y4m -c:v libaom-av1 <output>.webm
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If you’re on an older version of ffmpeg, you need to add -strict -2. Note that you can also use rav1e and SVT-AV1 in FFmpeg to encode AV1 videos.

AV1 Encoding Guide.

aomenc (Reference Encoder)

You’ll either have to compile aomenc yourself or you can use aomenc’s Windows builds by Marco Sousa.

aomenc.exe -o <output_file>.webm <raw_input>.y4m
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rav1e (Fastest)

You can find rav1e’s builds on GitHub. Note that rav1e only generates the raw video stream (saved as an ivf file) which needs to be muxed into a webm container file.

rav1e.exe <raw_input>.y4m -o <intermediate>.ivf
ffmpeg -i <intermediate>.ivf-c:v copy <output>.webm -hide_banner -loglevel error
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SVT-AV1

While there are some SVT-AV1 builds on GitHub, the project is marked as archived and SVT-AV1’s Gitlab Repo doesn’t have any prebuilt binaries so you’ll have to compile it yourself. However you get the binary, like rav1e, you need to mux the raw video stream into a webm container file.

SvtAv1EncApp.exe -b <intermediate>.ivf -i <raw_input>.y4m
ffmpeg -i $destIvf -c:v copy <output>.webm
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faraixyz
Farai Gandiya

Posted on June 11, 2021

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