Mix several video input streams into one video stream.

A description of the accepted options follows.

nb_inputs

The number of inputs. If unspecified, it defaults to 2.

weights

Specify weight of each input video stream as sequence. Each weight is separated by space. If number of weights is smaller than number of frames last specified weight will be used for all remaining unset weights.

scale

Specify scale, if it is set it will be multiplied with sum of each weight multiplied with pixel values to give final destination pixel value. By default scale is auto scaled to sum of weights.

duration

Specify how end of stream is determined.

longest

The duration of the longest input. (default)

shortest

The duration of the shortest input.

first

The duration of the first input.