Measures phase of input audio, which is exported as metadata lavfi.aphasemeter.phase, representing mean phase of current audio frame. A video output can also be produced and is enabled by default. The audio is passed through as first output.

Audio will be rematrixed to stereo if it has a different channel layout. Phase value is in range [-1, 1] where -1 means left and right channels are completely out of phase and 1 means channels are in phase.

The filter accepts the following options, all related to its video output:

rate, r

Set the output frame rate. Default value is 25.

size, s

Set the video size for the output. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. Default value is 800x400.

rc, gc, bc

Specify the red, green, blue contrast. Default values are 2, 7 and 1. Allowed range is [0, 255].

mpc

Set color which will be used for drawing median phase. If color is none which is default, no median phase value will be drawn.

video

Enable video output. Default is enabled.