1.6 Telerack Overview


We are following on from our previous extended study material for the Level 1 PFClean training (1.5 Workbench Overview) where we looked briefly at some of the tools and functionality of the Workbench. In this tutorial we shall be looking at the Telerack. Telerack allows fast automatic cleanup of tape based formats. Each Telerack node processes clips of the same standard format, and applies a single set of restoration parameters to all clips in a node. So let’s start where we left off in the Workflow Manager.

If you haven’t completed the previous tutorial (1.5 Workbench Overview) I would suggest going back and starting from there as we will be using some of the material and profiles we generated.

NOTE: To follow along in this tutorial, you will need access to the clips provided for the class. If you don’t have them to hand, below you will find the link to download the footage again.

Tutorial Footage

The footage used in the training.

Footage: PFClean_Training_Material.zip


01. Connecting Telerack

In tutorial 1.4 we talked about the standards based workflow. When we connected the Telerack to the output of Media bin 1, its standard was automatically set to PAL 576. This is because after we connected the Workbench and filtered the Full Aperture 2K clips out the media bin only contained PAL clips.

Since the Telerack node applies a single set of parameters to all clips in the node, these clips need to be of a single standard. To ensure this constraint, a standard format has to be set for the node. If the Media Bin contained mixed standards clips, the standard to use would have to be be set manually and all controls in the node will be disabled until a standard format has been set.

NOTE: Telerack will only work with common broadcast standards from SD to HD.

02. The Telerack Interface

Double click on the Telerack node to enter the node. When you first open a Telerack node, you will see the panel at the bottom with the current Worklist containing all three clips in the node.

The first clip in the Worklist is automatically loaded into the Cinema and will be updated as we activate and modify the Telerack filters. If you want to review the results of the current Telerack parameters on a different clip, simply click on its thumbnail in the Worklist.

The panel on the left of the Cinema shows the fixed pipeline of restoration filters. You can scroll through Telerack’s restoration pipeline with the cursor up/down keys on your keyboard or by pointing the cursor over the filters and using the mouse scroll wheel.

03. Using Telerack Restoration Filters

Let’s play through the first clip video_001 to evaluate the defects we are dealing with. This clip suffers from video dropouts, luminance bands and video noise. We are now going to activate the appropriate filters to deal with these issues.

The topmost filter in the Telerack pipeline is Fix Bands. This filter tackles horizontal bands as are most visible in frame 33. Click the On/Off switch to enable the filter C_1_6_image3. The filter’s parameters are now available for editing. With its default parameters, we do not see any desirable effect on the image, as the filter is looking for light bands. Click Dark as the Luma Band Type to fix the dark bands in this clip.

Next we are going to address the dropouts in the clip. These exist over a number of frames starting from frame 32, these would be difficult to paint out manually especially when they are over movement. Let’s use a filter in Telerack that will remove them in just a few clicks.

Use the arrow keys or your mouse wheel to scroll to the Fix Streaks filter and enable it. The Fix Streaks filter has removed 90% of the dropouts but there are still a few remaining. Let’s increase the Luma Drop Level % on the left of the filter to 45% to catch the remaining dropouts, adjusting the settings can be done either by clicking and dragging the slider or typing in the percentage box and pressing enter.

The next issue we identified in the clip was video noise. Scroll all the way down the filters to the De-Noise filter and activate it. In order to increase the denoising, we are going to increase the Intensity setting to 4.0 for all channels. You can do this by adjusting the parameter for each channel individually, or enable the chainlink “gang” button first. With gang enabled, the three channels will be adjusted simultaneously when you modify any one of them.

Click the Playblast button C_1_6_image4 to review the effect of the Telerack pipeline on our clip in real time. You can use the A/B split for a detailed before and after comparison.

Let’s click on the final clip in the worklist, video_004. If you play through you will notice a large amount of luminance pulsing in the clip from around frames 9 to 32. To tackle this we are going to use the De-Flicker filter. Using the arrow keys or scrolling the mouse wheel we are going to find the De-Flicker filter and then activate it. To check if the default settings are working let’s use the playblast button again and then the A/B split. Okay it’s not quite fixed the problem so let’s change the settings in the De-Flicker filter to improve the results. Just below the intensity % setting there is a small link button.

What this button will do is link all three color channels together so that when we adjust one it will adjust all of them. Now let’s change the intensity to 40% either by using the slider tab on one of the colour channels or by entering the number into the box and pressing enter. Playing through once more we can see that the adjusted settings have fixed the clip.

NOTE: Telerack parameters are automatically applied to all clips in the node.

04. Storing Presets

A Telerack pipeline with all its filter’s settings can be stored in a preset by clicking the Store button in the Telerack presets panel. These presets can then be used in other Telerack nodes in the project, or exported to other projects. These are a powerful way to work if you are dealing with a lot of tapes with similar artefacts.

To apply the pipeline stored in a preset in the current Telerack node, select the preset in the Telerack presets panel and click Use.

05. Getting Help

On the top left of the PFClean window, you will find a button with this icon C_1_6_image1. This is the help button and will open PFClean’s documentation in your web browser. Other help buttons with the same icon are located throughout PFClean’s user interface and provide more context sensitive help.

You have now completed the level 1 PFClean training and are now ready to move onto level 2 training and extended studies where we will take a closer look at film restoration in the Workbench.

Book your seat for the Level 2: A Closer Look at Film Restoration and Workflows in PFClean here.

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