Commit 8dcf322e authored by Sam Muirhead's avatar Sam Muirhead

update ffmpeg document

parent a35f8e26
......@@ -14,10 +14,12 @@ Not all of these projects fulfill all criteria, and the list is at a very, very
['Scaling the Citizen Sector' whitepaper](
[Open Building Institute](
[Embassy Network](
[Embassy Network](
[Open Architecture Collaborative](
### Art
[Ampliative Art](
[Ampliative Art](
### Activism
[Tactical Technology Collective](
[Rise Up](
......@@ -41,6 +43,7 @@ Not all of these projects fulfill all criteria, and the list is at a very, very
[Blender Open Movies](
[Apertus Cinema Camera Ecosystem](
[Female Filmmakers Initiative](
[Members' Media](
### Circular economy
[Open Source Circular Economy days]( _*full disclosure, I'm part of the team behind this one :)_
......@@ -116,6 +119,7 @@ Not all of these projects fulfill all criteria, and the list is at a very, very
[Robin Hood Coop](
### Money in politics (bad!)
......@@ -111,6 +111,12 @@ For maximum flexibility I find it useful to export animations from Synfig as PNG
ffmpeg -i inputImage.%04d.png -c:v libvpx -b:v 3M ouputVideo.webm
ffmpeg -y -probesize 5000000 -f image2 -r 24 -force_fps -i inputImage.%04d.png -c:v prores_ks -profile:v 3 -qscale:v 10 -vendor ap10 -pix_fmt yuv422p10le -s 1920x1080 -r 24
('-vendor ap10' makes video decoders think that this file was created by the expected Apple Quicktime program)
here the formulation %04d refers to an incrementation of file numbers. Synfig renders PNG sequences following this pattern - say I choose 'Animation.png' as the filename to export, Synfig will export each frame of my animation as:
......@@ -127,6 +133,24 @@ So when I tell FFmpeg to use **Animation.%04d.png** as an input, I am saying "lo
This assumes that the sequence starts at 0 - that means that you will need to add "-start_number 0013" between 'ffmpeg' and '-i' if you want to start with frame 13, for example.
# Create GIF from image sequence
This one's a bit trickier because GIFs are an awkward, innefficient and ancient technology - but they're well supported so they'll be sticking around a while longer....
GIF color palettes are only 256 colors, so it's best to analyze your input frames first to work out which 256 colors are most suitable.
So there's a first pass which generates a 'palette.png' file:
ffmpeg -y -i Animation.%04d.png \
-vf scale=640:-1:flags=lanczos,palettegen palette.png
Then you can reference that palette to convert the input files into a GIF:
ffmpeg -i Animation.%04d.png -i palette.png -filter_complex \
"scale=320:-1:flags=lanczos[x];[x][1:v]paletteuse" output.gif
# Double the speed of a video
Note: this just throws away every second frame, it's not actually doing frame blending or anything fancy - try [slomovideo]( for that.
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