O_Retimer

O_Retimer is designed to retime footage so that it plays back faster or in slow-motion. O_Retimer uses upstream motion vectors generated by an O_VectorGenerator node to retime the footage. These motion vectors describe how each pixel moves from frame to frame (see O_VectorGenerator). With accurate motion vectors, it is possible to generate an output image at any point in sequence timeline by interpolating along the direction of the motion.

Inputs and Controls

Connection Type	Connection Name	Function
Input	Motion	If a vectors are supplied here, O_Retimer uses them and does not require motion in the Source input. This can be useful if, for example, your input sequence is very noisy, as too much noise interferes with the motion estimation. In that case, you should supply a smoothed version of the sequence and an O_VectorGenerator node here.
Source	A stereo pair of images. If motion vectors aren’t embedded in the images, you should use a O_VectorGenerator node to calculate them.

Connection Type

Connection Name

Function

Input

Motion

If a vectors are supplied here, O_Retimer uses them and does not require motion in the Source input. This can be useful if, for example, your input sequence is very noisy, as too much noise interferes with the motion estimation. In that case, you should supply a smoothed version of the sequence and an O_VectorGenerator node here.

Source

A stereo pair of images.

If motion vectors aren’t embedded in the images, you should use a O_VectorGenerator node to calculate them.

Control (UI)	Knob (Scripting)	Default Value	Function
O_Retimer Tab
Local GPU	gpuName	N/A	Displays the GPU used for rendering when Use GPU if available is enabled. Local GPU displays Not available when: • Use CPU is selected as the GPU Device in the Preferences. • no suitable GPU was found on your system. • it was not possible to create a context for processing on the selected GPU, such as when there is not enough free memory available on the GPU. You can select a different GPU Device, if available, by navigating to the Preferences and selecting an alternative from the GPU Device dropdown. Note: Selecting a different GPU requires you to restart Nuke before the change takes effect.
Use GPU if available	useGPUIfAvailable	enabled	When enabled, rendering occurs on the Local GPU specified, if available, rather than the CPU. Note: Enabling this option with no local GPU allows the script to run on the GPU whenever the script is opened on a machine that does have a GPU available. You should also select this if you wish to render from the command line with the --gpu option. See Nuke 15 Release Notes for more information on the GPUs Nuke supports.
Views to Use	viewPair	Dependent on Source	Sets the two views you want to use to retime the clip. These views will be mapped for the left and right eye.
Timing	timing	Speed	Sets how to control the new timing of the clip: • Speed - select this if you wish to describe the retiming in terms of overall duration: double speed will halve the duration of the clip or half speed will double the duration of the clip. • Source Frame - select this if you wish to describe the retiming in terms of ‘at frame 100 in the output clip, I want to see frame 50 of the source clip‘. You’ll need to set at least two keyframes for this to retime the clip.
Speed	speed	0.5	Defines the retiming in terms of speed of playback and total duration: double-speed halves the duration of the clip and half-speed doubles the duration of the clip. Note: When you are retiming footage using the Speed method, ensure that you set the keyframes on the input frames, as setting keyframes on the input frames alters the number of output frames.
Frame	frame	1	Defines the retiming in terms of specifying source frames at different output points in the Viewer timeline. You need to set a minimum of two keyframes to use the Source Frame method. For example, to slow down a 50 frame clip by half, set the Source Frame to 1 at frame 1 and the Source Frame to 50 at frame 100. The default expression will result in a half-speed retime.
Edges
Output edges to alpha	outputEdgesToAlpha	disabled	When enabled, output the edges to the alpha channel. Use the alpha channel as an overlay to determine where the edge correction is applied.
Adjust Edges	adjustEdges	0	Sets the size of the edge mask. To dilate the mask, use a positive value. You can use a negative value to erode the mask.
Feather	featherEdges	2	Controls how much feathering to apply to the edges. Increasing the Feather value softens the edges; decreasing the value, sharpens the edges.