FFmpeg filter graph by Ciro Santilli 37 Updated 2025-07-16
Filter graphs are a thing of great beauty. What an amazingly obscure domain-specific language, but which can produce striking results with very little!!!
ffplay -autoexit -nodisp -f lavfi -i '
sine=frequency=500[a];
sine=frequency=1000[b];
[a][b]amerge, atrim=end=2
'
which creates a graph:
                              +--------+
[sine=frequency=500]--->[a]-->|        |
                              | amerge |-->[atrim]-->[output]
[sine=frequency=1000]-->[b]-->|        |
                              +--------+
and plays 500 Hz on the left channel and 1000 Hz on the right channel for 2 seconds.
So we see the following syntax patterns:
  • sine, amerge and atrim are filters
  • sine=frequency=500: the first = says "araguments follow"
    • frequency=500 sets the frequency argument of the sine filter
    • for multiple arguments the syntax is to separate arguments with colons e.g. sine=frequency=500:duration=2
  • ;: separates statements
  • [a], [b]: sets the name of an edge
  • ,: creates unnamed edge between filters that have one input and one output
A list of all filters can be obtained ith:
ffmpeg -filters
and parameters for a single filter can be obtained with:
ffmpeg --help filter=sine
Related question: stackoverflow.com/questions/69251087/in-ffmpeg-command-line-how-to-show-all-filter-settings-and-their-parameters-bef
TODO dump graph to ASCII art? trac.ffmpeg.org/wiki/FilteringGuide#Visualizingfilters mentions a -dumpgraph option, but haven't managed to use it yet.
Bibliography:
ffplay by Ciro Santilli 37 Updated 2025-07-16
Awesome tool to view quick stuff quickly without generating files. Unfortunately it doesn't support all options that the ffmpeg CLI supports, e.g. ffplay multiple input files. One day, one day.
FFmpeg video synthesis by Ciro Santilli 37 Updated 2025-07-16
Video with a solid color:
Display count in seconds on the video:
Bibliography:
Display manager by Ciro Santilli 37 Updated 2025-07-16
Check which you you have:
systemctl status display-manager.service
Tested on Ubuntu 23.10 I see:
● gdm.service - GNOME Display Manager
     Loaded: loaded (/lib/systemd/system/gdm.service; static)
     Active: active (running) since Sun 2023-12-24 10:34:50 GMT; 23min ago
    Process: 1827 ExecStartPre=/usr/share/gdm/generate-config (code=exited, status=0/SUCCESS)
   Main PID: 1850 (gdm3)
      Tasks: 4 (limit: 71817)
     Memory: 6.8M
        CPU: 119ms
     CGroup: /system.slice/gdm.service
             └─1850 /usr/sbin/gdm3
which means I have GNOME Display Manager.
This is one of those idealistic W3C specifications with super messy implementations all over.

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