work

c++

Asciinema, gifs

Recording typing

asciinema rec demo.cast

Press Ctrl + D when done recording.

asciinema upload demo.cast will return the address - that will show how to embed it on a webpage or download a gif.

Can add data-autoplay="true" data-loop="true" to the page.

Scripting

The asciinema-rec_script script can be used to record a script.

Remember to load the environment.

./asciinema-rec_script script_name.sh

Agg: from .cast to gif

Make sure to:

• comment out all echo commands in /etc/zshrc_Apple_Terminal
• remember to set PROMPT_EOL_MARK='' in .zshrc

agg --theme asciinema --font-size 50 --cols 132 --rows 22 --speed 2  ifarm.cast ifarm.gif

ffmpeg: from .mov gif

Here’s an example to convert a mov file to a gif. The two steps ensure optimal colors:

ffmpeg -i input.mov -vf "fps=15,scale=800:-1:flags=lanczos,palettegen" -y palette.png
ffmpeg -i input.mov -i palette.png -lavfi "fps=15,scale=800:-1:flags=lanczos[x];[x][1:v]paletteuse" -loop 0 output.gif

where:

• fps=15 → frame rate (lower for smaller file)
• scale=800:-1 → width 800 px, keep aspect ratio
• flags=lanczos → high-quality scaling filter
• -loop 0 → infinite loop

Additional gif goodies

To concatenate 3 gifs:

W=860
H=600
FPS=15

ffmpeg -i a.gif -i b.gif -i c.gif \
  -filter_complex "\
[0:v]fps=${FPS},scale=${W}:${H}:force_original_aspect_ratio=decrease,pad=${W}:${H}:(ow-iw)/2:(oh-ih)/2[v0]; \
[1:v]fps=${FPS},scale=${W}:${H}:force_original_aspect_ratio=decrease,pad=${W}:${H}:(ow-iw)/2:(oh-ih)/2[v1]; \
[2:v]fps=${FPS},scale=${W}:${H}:force_original_aspect_ratio=decrease,pad=${W}:${H}:(ow-iw)/2:(oh-ih)/2[v2]; \
[v0][v1][v2]concat=n=3:v=1:a=0,scale=${W}:${H},split[x][y]; \
[x]palettegen=reserve_transparent=1[p]; \
[y][p]paletteuse=dither=bayer" \
  -loop 0 out.gif

where:

• -loop 0 – tells the GIF encoder to loop forever (0 = infinite).
• [0:v], [1:v], [2:v] – take video stream from input #0 (a.gif).
• FPS=15 – re-sample to 15 frames per second

To make sure a gif loops forever:

ffmpeg -i in.gif \
  -filter_complex "fps=15,split[x][z];[x]palettegen[p];[z][p]paletteuse" \
  -loop 0 out.gif