A filter is represented by a string of the form: [’) is encountered.
The name and arguments of the filter are optionally preceded and followed by a list of link labels.
For example in the filterchain the split filter instance has two output pads, and the overlay filter instance two input pads.
The first output pad of split is labelled "L1", the first input pad of overlay is labelled "L2", and the second output pad of split is linked to the second input pad of overlay, which are both unlabelled.
If the evaluation is non-zero, the filter will be enabled, otherwise the frame will be sent unchanged to the next filter in the filtergraph. The configure output will show the audio filters included in your build.
Below is a description of the currently available audio filters.
A first level escaping affects the content of each filter option value, which may contain the special character used by the filtergraph description.
Finally, when you specify a filtergraph on a shell commandline, you need to perform a third level escaping for the shell special characters contained within it.
The preceding labels , are associated to the output pads.
Filters in the same linear chain are separated by commas, and distinct linear chains of filters are separated by semicolons. The points where the linear chains join are labelled by names enclosed in square brackets.
In the example, the split filter generates two outputs that are associated to the labels filter in order to simulate a specific input file.
It is possible to specify swscale flags for those automatically inserted scalers by prepending Filtergraph description composition entails several levels of escaping.
See (ffmpeg-utils)the "Quoting and escaping" section in the ffmpeg-utils(1) manual for more information about the employed escaping procedure.
Each link has one input pad on one side connecting it to one filter from which it takes its input, and one output pad on the other side connecting it to one filter accepting its output.