What Is Davinci Resolve Optical Flow + How To Use It In 2024

Utilize DaVinci Resolve's Optical Flow for smoother slow-motion effects and consistent frame rate conversions in your video projects. By analyzing pixel movement between frames, it generates in-between frames for a more natural playback, but always review the results to avoid potential artifacts.

February 9, 2024
What Is Davinci Resolve Optical Flow + How To Use It In 2024
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If you've ever used After Effects before, you'll know that there is a popular plugin called RSMB that lets you create realistic ultra slow-motion effects, even with footage as low as 24 FPS. Similarly, DaVinci Resolve boasts its own powerful feature known as Optical Flow.

What Does Optical Flow Do In Davinci Resolve?

Before you learn how to use the Optical Flow, here's what it actually is:

DaVinci Resolve's Optical Flow is a sophisticated technology used for motion estimation within video clips. In simpler terms, it's a tool that analyzes the motion between frames in a video and then generates new frames to create smoother transitions. This is especially useful when slowing down footage or converting frame rates, as it can produce smoother, more natural-looking results compared to traditional frame interpolation methods.

How Does It Work?

Optical Flow works by analyzing the pixel movement between consecutive frames in a video. By understanding this movement, it can then predict and generate the in-between frames that didn't exist in the original footage. For example, if you have a video shot at 30 frames per second (fps) and you want to slow it down, traditionally, this would result in a choppy playback because there aren't enough frames to fill the slowed-down time. With Optical Flow, DaVinci Resolve can generate the missing frames by analyzing the motion in the original frames, resulting in smoother slow-motion playback.

When to Use Optical Flow?

  1. Slow Motion: If you've shot footage at a standard frame rate (like 24fps or 30fps) and you want to slow it down for a slow-motion effect, Optical Flow can help make that slow motion look smoother and more cinematic.
  2. Frame Rate Conversion: If you're working with footage from different sources with varying frame rates, Optical Flow can be used to convert them to a consistent frame rate without the jittery or ghosting effects that can sometimes occur with traditional methods.
  3. Stabilization: While Optical Flow's primary use is for frame interpolation, its motion estimation capabilities can also aid in stabilizing shaky footage.

DaVinci Resolve Not Working?

While Optical Flow is a powerful tool, it's not always perfect. Depending on the complexity of the motion in the footage or the presence of rapid changes in lighting, it can sometimes produce artifacts or unnatural-looking results. It's always a good idea to review the results closely and use Optical Flow judiciously.

Davinci Resolve 18 Optical Flow Tutorial

Accessing Retime Controls in DaVinci Resolve

This part is always the most fun. It's where your vision starts to take shape. If you've been following along, you'll find that DaVinci Resolve offers a plethora of tools to refine your video. Let's dive into the Retime Controls.

  1. Highlighting Your Clip:
  2. Open DaVinci Resolve and import the footage you wish to work on.
  3. In the timeline, click on the clip you intend to edit. This action will highlight it, indicating it's ready for modifications.
  4. Navigating to Retime Controls:
  5. Right-click on the highlighted clip. A dropdown menu will appear.
  6. Look for the option labeled "Retime Controls" and select it. Alternatively, you can use the shortcut Control - R on your keyboard. This is where you'll be making the magic of slow motion happen.

Defining the Slow Motion Section

Guess what? Now that you've accessed the Retime Controls, it's time to define which part of your clip you want in slow motion.

  1. Setting the Speed:
  2. On your clip, you'll notice a percentage, typically set at 100%, indicating the playback speed.
  3. Click on this percentage, and a dropdown will appear. This dropdown allows you to set the speed of your clip. But before adjusting the speed, you need to define the section you want to slow down.
  4. Adding Speed Points:
  5. After deciding the starting point of your slow-motion section, click on the black arrow next to the 100%. A menu will pop up.
  6. Select "Add Speed Point". This action marks the beginning of your slow-motion section.
  7. Move further along your clip to where you want the slow motion to end and add another speed point. Think of these points as bookends; they're holding the section of the clip you want to modify.

Adjusting the Playback Speed

Now that you've defined the section, it's time to adjust its speed. Believe me, this step is simpler than it sounds.

  1. Changing the Speed:
  2. Click on the percentage within the section you've defined with speed points. A dropdown will appear.
  3. From this dropdown, you can select a new playback speed. For a slow-motion effect, you might want to choose something like 25%. This means your clip will play back at a quarter of its original speed within the defined section.

Fine-Tuning with Retime and Scaling

In a nutshell, the Retime and Scaling settings are where you refine the quality of your slow-motion effect. This is where you ensure the slowed-down section doesn't look jittery or unnatural.

  1. Accessing Retime and Scaling:
  2. With your clip still highlighted, look to the top right corner of your screen. You'll find the "Inspector" panel.
  3. Within the Inspector, locate and select the "Retime and Scaling" option. This is where you'll find settings specifically designed for playback adjustments.
  4. Optical Flow & Speed Warp:
  5. Under "Retime Process", select "Optical Flow". This tool analyzes your footage and creates new frames to make the slow motion smoother.
  6. For "Motion Estimation", choose "Speed Warp". This further refines the smoothness of your clip, ensuring the motion looks as natural as possible.

Rendering Your Adjustments

All in all, after making these adjustments, you need to render them to see the final result. Frankly, this step is crucial because it allows DaVinci Resolve to process all the changes you've made.

  1. Render in Place:
  2. Right-click on your clip in the timeline.
  3. From the dropdown menu, select "Render in Place". This action will process all the changes you've made, giving you a smooth slow-motion effect.