Chapter 12: Editing Image Sequences

There are several ways to change a sequence of image frames in RAYZ, depending on the type of changes you need to make.

You can use parameters in the Image In node to import a subset of the entire range of frames in the sequence and specify at which frame number in the shot the sequence should start. These parameters are explained in the section of the Image In node description on Frame Range to Import in chapter 14. To perform more complex editing tasks, however, you can use the Clip Editor view or the Retime Footage utility.

In This Chapter

Using the Clip Editor

Using the Retime Footage Utility

Choosing an Appropriate Method

The Clip Editor displays all source node imagery as film strips on a timeline. You can shrink, stretch, or time-shift a clip or split it into segments of any length, each of which can be modified individually.

You do not have to import a sequence into RAYZ to modify it in Retime Footage. This utility is used to shrink or stretch a clip by editing a curve that controls the redistribution of frame data.

The Cinespeed option, which is available only in Retime Footage, analyzes how the image changes from frame to frame and uses this data along with the specified curve shape to retime the clip.

Note:

 

To re-sequence a clip in a downstream node (the output of a composite node, for example) use the Sequence Node in chapter 21 instead.

Using the Clip Editor

The Clip Editor is used to re-sequence source imagery. The most basic, and most common, sequencing tasks can be done directly in the source node, without opening the Clip Editor. In the Clip Editor, however, you can view the sequence as a film roll and perform more complex edits.

In the Image In Node Panel, for example, you can specify the starting frame number to use for the sequence in the RAYZ network. You can also specify that only a subset of the total frames available on disk are imported. To split a sequence or add holds, on the other hand, you need to use the Clip Editor.

The Clip Editor view consists of a Clip Browser panel and a Timeline. All source nodes in the file are listed in the Clip Browser automatically. Only those clips you specify are displayed in the timeline, however.

Image showing the Clip Editor view with the clip list panel and the timeline.

Fig. 12.1 The Clip Browser panel (left) can be used to control which clips are displayed in the Timeline (right).

Thumbnail Display

To display thumbnail images for each frame in the Timeline strip, check the Thumbnails box in the control strip at the top of the Clip Editor.

The "Main Clip Edit Controls" strip is accessed from the Tools menu on the left side of the Clip Editor title bar.

Clip Browser

To display a clip in the timeline, check the associated box in the list of clips in the Clip Browser. All clips that have been enabled in the clip list appear in the timeline as frame strips. Each item in the clip list can be expanded to access the sequence parameters for that clip.

Sequence Parameters

Each sequence in the Clip Browser list can be expanded to access two rows of parameter fields:

Image showing the parameters in a clip list entry.

Fig. 12.2 Clip Browser entry for an Image In node named "Dove_Side."

Segment Parameters

When you split a clip in the Timeline, the clip list parameters for that clip are duplicated so that you can edit each segment individually.

Image showing the duplicate parameter groups created for each segment in a split clip.

Fig. 12.3 This clip has been split into two segments and an ease function applied to the second segment.

For example, you might split a clip and reassign the same range of source frames to both segments to create a loop. Or you could assign a single frame to a segment and set the segment length to however many frames you wanted to hold the frame.

Image showing an example of how split segments can be used to create loops and holds.

Fig. 12.4 Splitting a clip into segments enables you to create loops and holds for specific frames of the source image.

Timeline

The timeline in the Clip Editor is used to examine the frames visually and to re-sequence clips interactively. Any changes you make in the timeline are also reflected in the sequence parameters for that clip in the Clip Browser list.

As explained in the previous section on the Clip Browser, any clip that is checked in the clip list will appear in the timeline. The timeline displays each clip as a horizontal strip of frames and the clips are stacked vertically.

Like the Worksheet, you can move the timeline around in the view frame by dragging with the middle mouse button or scale it by holding down the Control key as you drag the scroll bar located at the bottom.

Current Frame Indicator

The blue bar that runs vertically through the timeline is the current frame indicator. Drag the blue bar to change the current frame. This updates the data displayed in the Image Viewer and Node Panel.

Image showing the frame indicator in the timeline.

Fig. 12.5 Current frame is 8, as indicated by blue bar.

Tip:

 

Press the Backspace key to snap the viewspace back to its default position with the first frame lined up on the left side of the timeline.

Thumbnail Display of Frame Images

To see thumbnail images of each frame, check the Thumbnails box in the control strip at the top of the Clip Editor.

Editing in the Timeline

The timeline is used to edit a clip by dragging the entire clip back and forth across the timeline to reposition it in time, or by dragging one end of the clip by the edit handle to change its length. Nonlinear interpolation functions can be applied to a clip, and the clip can be split into segments, each of which can be edited separately.

Tip:

 

Any edit you make in the timeline can be fine-tuned in the associated Sequence Parameters in the clip list.

Time-Shift

Drag the entire clip back and forth in the Clip Editor to time-shift it.

Time-Stretch/Shrink

Drag the edit handle (see Fig. 12.6 below) at either end of the clip or segment in the direction that will stretch or shrink it.

You have two options for stretching a segment:

Split

Ctrl-click between two frames or anywhere on the preceding frame to split a clip into two separate segments at that point. Edit handles will appear, separating the two frames, and new parameter group will be created for the segment in the clip list entry.

Image showing the edit handles that appear between two frames when you split a clip.

Fig. 12.6 Example of a clip split into separate segments between frames 3 and 4. Note the edit handles that appear between the split frames.

Single-Frame Segments

To split the first frame in a sequence from the rest of the frames (as when you want to add a hold), Ctrl-click on the frame. To split the last frame, Ctrl-click on the preceding frame. For a frame in the middle of a sequence, Ctrl-click on both sides of the frame.

Removing a Split

To delete a segment, drag its edit handle until the segment disappears, or set the Out Length value for the segment to 0 in the clip list.

Add Holds

To hold a frame, start by splitting it into a separate segment, as described above. Once the frame has been split, right-hold on the frame to access the popup function menu and select "Hold." Then you can drag the frame by its edit handle to stretch the hold, or edit the length field for the new segment in the clip list.

Apply Function

To apply a nonlinear interpolation such as an ease function, right-click and hold on any frame in the segment to access the popup menu, which includes the following functions:

The function you select from the menu will be applied to the clip (or to the current segment of the clip in the case of a split clip).

Using the Retime Footage Utility

The Retime Footage utility is a panel, accessed from within RAYZ, that is used to retime a sequence of image files stored on your local hard drive or on a shared storage device on your network.

Image showing the Retime Footage panel.

Fig. 12.7 The Retime Footage panel.

The retimed frames are written to disk in the location you specify, and you can then import the retimed footage into RAYZ for further modification and integration into a shot.

How Retime Footage Works

Retime Footage works by using a distribution curve to plot the rate of change from input to output. There are three retiming methods to choose from:

They all use the distribution curve to specify the retiming, but each uses a different method to calculate how the input image data is handled.

Frame Rounding

The fastest method is Frame Rounding, which duplicates the previous or next frame when lengthening a clip and throws away frames when shortening a clip. It chooses the frame to duplicate or discard based on its interpolation value in the retiming curve, which is rounded to the nearest whole number. If, for example, the value is 5.7, frame 6 will be duplicated; if the value is 5.2, however, frame 5 will be duplicated.

Frame Averaging

Frame Averaging, unlike Rounding, creates new frame images when necessary by averaging the pixels in the adjacent frames. The contribution of each adjacent frame is weighted based on the interpolation value in the retiming curve. If, as in the frame rounding example above, this value is 5.7, 70 percent of frame 6 and 30 percent of frame 5 will be used to generate the new frame.

Cinespeed

The Cinespeed option incorporates the Cinespeed algorithms used in the Cineon Time Warp utility. Cinespeed actually compares and analyzes the image data from frame to frame, creating vector/occlusion files that represent the areas and magnitude of change. This data is used, rather than simple averaging, to determine how frame images are blended.

These vector files can take a while to process, but they can be saved and reused if you need to fine-tune the shape of the distribution curve.

Note:

 

Unlike the other retiming operations, Cinespeed does not operate on four-channel images. You can specify RGBA image files for retiming with Cinespeed, but the alpha channel will not be processed and the retimed footage will be RGB only.

the Retime Footage Panel

To retime a sequence, open the Retime Footage panel and follow these steps:

  1. Specify the image sequence to be retimed in the Input parameters.
  2. Specify where the retimed footage should be saved, and in what format, in the Output parameters.
  3. Select the method to use from the Operation menu: Averaging, Rounding, or Cinespeed. (If you select Cinespeed, refer to the instructions below on setting Cinespeed options.)
  4. Adjust the retiming curve, as described in Adjusting the Retiming Curve.
  5. Set the Render Range to match the output.
  6. Press the Retime button, located at the bottom of the panel, to render the retimed footage.

Image showing the status information box.

Fig. 12.8 Status information updates during the render.

While the retimed footage is being rendered, a status box pops up to display the current frame being rendered and the estimated time remaining.

When Cinespeed is used, it also indicates the phase being executed: Analysis, when the vector files are created, and Retime, when the retimed footage is being rendered.

Setting Cinespeed Analysis Options

If Cinespeed is the selected operation, use the Vector Files parameter in the Cinespeed Analysis group to specify where the vector files generated by this method should be saved. Optionally, you can also set the Breaking, Smoothness, and High Quality parameters.

Vector files are given the name "vector.$F$.dat" by default. Whatever name you use, be sure to include the ".dat" extension.

Use the Render Range, when applicable, to specify a subset of the total frame range for retiming to avoid processing unnecessary frames.

Image showing the Cinespeed Analysis parameters.

Fig. 12.9 Cinespeed Analysis parameters in the Retime Footage panel.

Overwrite Vectors

You can reprocess a clip after adjusting the retiming curve without rewriting the vector files by turning off the Overwrite Vectors option. However, if you need to change an analysis option, such as Breaking, you will have to overwrite the old vector files.

Breaking

Select an option from the Breaking menu to correspond to the amount of movement in the scene being retimed. The default Breaking option is Normal, however, you can also choose Harder, Soft, and Very Soft.

The busier the scene--the more moving objects it has--the "harder" the option should be. Be aware, however, that a harder option increases the time needed to process the sequence.

Smoothness

Use the Smoothness parameter to specify how important smoothness should be. The default value, 0, is effectively neutral. Setting a positive value indicates that smoothness is more important; a negative value, that it is less important.

Higher Quality (Slower)

By default, the combined luminance values of the RGB image are analyzed. To analyze the red, green, and blue channels individually, check the Higher Quality box. As the label states, this option will take much longer to analyze.

Setting Cinespeed Motion Blur Options

To add motion blur to the retimed footage, check the Motion Blur box.

Image showing the Cinespeed Motion Blur parameters.

Fig. 12.10 Cinespeed Motion Blur parameters in the Retime Footage panel.

Additional parameters, Aperture In and Out, will become active which can be used to adjust the default aperture angles for the motion blur.

Aperture In

Use the Aperture In parameter to specify the aperture angle of the input in a range of 0-170 degrees. This parameter value should be set to match the angle used when the footage was shot, if known; otherwise leave it at the default value of 0. For CG imagery, use 0.

Aperture Out

Use the Aperture Out parameter to specify the aperture of the motion blurred output in a range of 0-720 degrees.

Adjusting the Retiming Curve

You can manipulate the curve directly in the graph, or use the associated Keypoint Viewer to edit the curve values numerically.

You can add keypoints to the curve and specify different distribution functions for each curve segment:

Image showing the graph in the Retime Footage panel.

Fig. 12.11 Retime curve graph (left) and Keypoint Viewer (right). The vertical axis of the graph represents the input frame range; the horizontal axis, the retimed frame range.

You can save retiming curves, just as you would animation curves in the Curve Editor, and reuse them on different sequences. Right-hold in the graph, anywhere except on the curve, to access the popup menu used to save and load retiming curves.

The curve graph interface works like the one in the Curve Editor view. For detailed information about manipulating a curve, refer to Creating and Editing Keypoints in chapter 8, Controlling Interpolation of Curve Values in chapter 8, and Editing Keypoints Numerically in chapter 8.

Render Range Parameters

In most cases you will set the Render Range parameters to fit the range of the retimed output sequence. However, you can also specify a subset of the retimed output when applicable.

To adjust the Render Range parameters, simply type new values in the Start and End fields.

Tip:

 

To run a clip backward in time, enter the last frame in the Start field and the first frame in the End field.

Saving Retime Footage Settings

You can save the current panel settings to a file and reload them into the Retime Footage panel at any time by using the Save and Load buttons located at the bottom of the panel.

Press the Save button and a dialog box will appear in which you specify the name and location of the file, which should have a ".retime" file extension. RAYZ will append this extension by default when you save the retime settings file.

To load the saved settings, press the Load button and select a saved retime settings file in the dialog box, navigating to the appropriate directory if necessary.

Retiming Sequences from the Command Line

You can retime an image sequence from the command line, if the settings for the sequence were saved as a ".retime" file, by using the rayz_retime command. Specify the start and end frames of the retimed sequence and the name of the .retime file:

rayz_retime -start <number> -end <number> filename.retime