Conversely, sources can be created from them using and .įilters are configured within the closure of a function. * (unlabeled) : (default: None)įilters input and output are abstract values of type and. For instance: Ffmpeg filter: Add echoing to the audio. If enabled, the filters should appear as operators, prefixed with ffmpeg.filter. They are enabled in liquidsoap when compiled with the optional ffmpeg-avfilter. It's kind of like using /dev/null if you're familiar with that.FFmpeg filters provide audio and video filters that can be used to transform content using the ffmpeg library. If you have a filterchain that you want to temporarily omit then you can terminate it into a sink, such as anullsink. One use is to test complicated filtergraphs.

Example to output a video test pattern, 3 seconds, 1280x720: ffmpeg -f lavfi -i testsrc2=d=3:s=1280x720 output.mp4Ī sink is less useful for most users. These filters can generate video or audio by themselves with no input needed, so there are no input pads.

Source filter examples include testsrc2, color, and sine. This may make more sense if you've ever used software that uses node graph architecture such as Nuke or the unfortunately discontinued Apple Shake.Ī filter with no input pads is called a 'source', and a filter with no output pads is called a 'sink'. One copy is flipped, and then the hstack filter stacks them side-by-side to create the output.Įach filter is linked, and each link is connected to an input 'node' (pad) and an output 'node' (pad). In this example the split filter makes two identical copies of a video. This can be visually represented with the graph2dot tool: Replacing it with the word 'node' may make it more comprehendible. I never liked the term 'pad' when used in the context of filtering and I don't know why that term was used. The fleshy cushion-like underpart of the foot of a cat, dog, etc

Ffmpeg filter graph