Shake 4: Using Convert and Adaptive retiming with the existing field workflow

The Basics of Convert and Adaptive Retiming

In Shake 4, Adaptive retiming provides a high-quality interpolation of the elements in motion by means of motion-estimation retiming. The Convert tool provides high-quality format conversion using any combination of the following processes:

* Retiming through motion estimation
* Deinterlacing through motion estimation
* Reinterlacing
* Scaling using motion estimation

There are a couple of important things to know about how the Convert tool and Adaptive retiming work with the existing field workflow in Shake.
Using with Telecine material (3:2 pulldown)

* The Convert Tool
The interlacing and deinterlacing parameters in the new Convert tool assume regular video interlacing—not 3:2 pulldown. To remove or introduce 3:2 pulldown, you will need to use the traditional pulldown parameter in the Timing tab of the FileIn node. For example:

o To create a 30 fps (frames per second) clip with pulldown, choose Convert, then change the frame rate to 24 fps, non-interlaced, FileOut, FileIn, and set the "pulldown" parameter in the Timing tab of the new FileIn to "24-30."
o To convert material with existing pulldown, set the "pulldown" parameter in the Timing tab to "30 to 24," then use the Convert tool to convert the now 24 fps source to whatever you desire. The Convert tool will recognize a FileIn node that's set this way as being a solid 24 fps.

* Adaptive Retiming
Although the Shake 4.0 manual goes into depth about working with 3:2 pulldown, what we describe above is the basic 3:2 workflow in Shake, which includes Adaptive retiming.

Using with Field Rendering

* The Convert Tool
If you convert footage to an interlaced format with the Convert tool, you shouldn't field render it. If you need to field render a composite that contains footage that's been converted to an interlaced format, you have two options:

o The interlaced output of the Convert tool needs to use a FileOut node (not field rendered) and then used in a composite with the traditional deinterlace/field-render workflow.
o You can set the output of the Convert tool to "non-interlaced" and then field render the composite. However, the Convert tool has to include a frame rate change or source deinterlacing, so in some situations (a same format blowup, for example) you will have to use the FileOut/FileIn method. You can test if a Convert setup can be field rendered by turning off OutputFrameInterlaced and then stepping through by half frames. If the movement is continuous through the half frames, you can field render the clip along with the composite.

* Adaptive Retiming
You can field render adaptively retimed footage. The retiming occurs in half frame increments for this purpose.

Preprocessing is Recommended

Because of these issues, and because of the heavy processing required for high-quality conversions and heavy speed changes, it's probably best to think of conversion and Adaptive speed changing as something to preprocess rather than keep live in a compositing script.