Blend two video frames into each other.
The blend filter takes two input streams and outputs one
stream, the first input is the "top" layer and second input is
"bottom" layer. By default, the output terminates when the longest input terminates.
The tblend (time blend) filter takes two consecutive frames
from one single stream, and outputs the result obtained by blending
the new frame on top of the old frame.
A description of the accepted options follows.
- c0_mode, c1_mode, c2_mode, c3_mode, all_mode
-
Set blend mode for specific pixel component or all pixel components in case of all_mode. Default value is
normal.Available values for component modes are:
- addition
- grainmerge
- and
- average
- burn
- darken
- difference
- grainextract
- divide
- dodge
- freeze
- exclusion
- extremity
- glow
- hardlight
- hardmix
- heat
- lighten
- linearlight
- multiply
- multiply128
- negation
- normal
- or
- overlay
- phoenix
- pinlight
- reflect
- screen
- softlight
- subtract
- vividlight
- xor
- c0_opacity, c1_opacity, c2_opacity, c3_opacity, all_opacity
-
Set blend opacity for specific pixel component or all pixel components in case of all_opacity. Only used in combination with pixel component blend modes.
- c0_expr, c1_expr, c2_expr, c3_expr, all_expr
-
Set blend expression for specific pixel component or all pixel components in case of all_expr. Note that related mode options will be ignored if those are set.
The expressions can use the following variables:
- N
-
The sequential number of the filtered frame, starting from
0. - X, Y
-
the coordinates of the current sample
- W, H
-
the width and height of currently filtered plane
- SW, SH
-
Width and height scale depending on the currently filtered plane. It is the ratio between the corresponding luma plane number of pixels and the current plane ones. E.g. for YUV4:2:0 the values are
1,1for the luma plane, and0.5,0.5for chroma planes. - T
-
Time of the current frame, expressed in seconds.
- TOP, A
-
Value of pixel component at current location for first video frame (top layer).
- BOTTOM, B
-
Value of pixel component at current location for second video frame (bottom layer).
The blend filter also supports the framesync options.
Examples
-
Apply transition from bottom layer to top layer in first 10 seconds:
blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
-
Apply linear horizontal transition from top layer to bottom layer:
blend=all_expr='A*(X/W)+B*(1-X/W)'
-
Apply 1x1 checkerboard effect:
blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
-
Apply uncover left effect:
blend=all_expr='if(gte(N*SW+X,W),A,B)'
-
Apply uncover down effect:
blend=all_expr='if(gte(Y-N*SH,0),A,B)'
-
Apply uncover up-left effect:
blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
-
Split diagonally video and shows top and bottom layer on each side:
blend=all_expr='if(gt(X,Y*(W/H)),A,B)'
-
Display differences between the current and the previous frame:
tblend=all_mode=grainextract