Create a Supplemental IMF in Dolby Vision - Frame replacement

Create a Supplemental IMF in Dolby Vision - Frame replacement

The purpose of this tutorial is to explain you how to replace image frames in a packaged IMF in Dolby Vision, without requiring an update of the Dolby Vision metadata. This method creates a supplemental version.

For details on how to perform certain operations, please refer to MIST user manual.

In this tutorial we have the following sources:
  1. An Original Version IMF in Dolby Vision (Meridian)
  2. A TIFF sequence in UHD P3D65 PQ 16 bit 23,976fps.
The files used for this example are not exhaustive. Source material must be of a quality that is equal to or greater than the one required by Netflix. In case of doubts about the quality of your sources, please refer to the technical specifications of Netflix in force.

I. Start with importing the original version IMF

When importing an IMF Package, MIST will automatically create a new project. Start by importing the original version IMF :




You can then inspect the package:




Then process to a validation, either using MIST validation tests or Photon.

In this case our source is an Application 2e with Netflix specifications. for this reason wee can see warnings regarding the other applications:





When clicking on OK, MIST creates a new timeline with the package's assets.




One video track and a 5.1 soundfield are packaged in one segment. 




We can also see the presence of Dolby Vision metadata thanks to the white bar on the clip. This bar tells us that the clip is read-only. If we look in the CMS tab into the COMPOSITION SETTINGS, we can see that MIST has detected Dolby Vision technology:





II. Performing frame replacement

In this tutorial, we seek to replace a fixed frames clip written in English by the same clip but written in Japanese. This manipulation does not require any new updates to Dolby Vision metadata. We will take those of the clip in English and apply them on the Japanese version.

First, we need to import our insert into the project's Library. 
In our case, this is a 16 bit UHD P3D65 PQ TIFF image sequence. TIFF files do not have metadata indicating their frame rate. It is therefore necessary to specify it BEFORE importing it into the Library.

To do this, go to the PROJECT ( `F1` ) module then in the MEDIA tab and change the Default Frame Rate:




MIST will now be able to know how to interpret the image sequence we provide it with.

We now can browse through the Windows file browser to drag and drop the media into our Quick Library.

The Dolby Vision metadata present in the package are in read-only mode. To be able to copy the one we need to apply to our insert, we first need to make them editable.

That's why we're going to apply the cut function on a duplicated track of our IMF. To duplicate, right-click on the layer and choose Duplicate:





You can rename your track by double clicking on it if necessary. In our case we will name it V2.

Then, apply the cut function on track V2 by right clicking on the clip and then Cut ... in the menu DOLBY VISION METADATA:




Create a new video track by clicking on the V+ button and then click on the name of the track to make it active. We will enjoy this time to also name the track V3

From the Quick Library, select your insert and place it to the desired location:




Now we need to copy the DoVi metadata: to do this, open the QuickStore ( `Q` ), click on the source clip in V2 and store the metadata ( `M` ). Click on your V3 insert and paste the metadata ( `B`):




Once the metadata copy is completed, we can delete the V2 and go to the IMF export tool.

Remember to verify your composition settings before accessing the export tool. Check if the active area aspect and the mastering display settings are matching the one used by the Dolby Vision metadata file imported.

III. The IMF export module

To access the IMF export module, click the IMF button at the bottom left of the timeline.

In the IMF Export Tool, in the GENERAL tab, name your IMF and select the Netflix HDR Dolby Vision template from the drop-down menu:




On the ESSENCE and VIDEO tab, make sure that the Dolby Vision check box is checked and prefer the GPU engine to the CPU one in the drop-down menu on your right:




In the AUDIO tab, make sure that both 5.1 and stereo audio configurations are present. Name them, change the language if necessary and check the mapping of the audio channels:




Then copy and paste the composition name into the packing list annotation:




In the Naming tab, we can use some tags to name the assets and find them easily. Here we want that each asset takes the name of the composition.
For that, we need to use the $PackageName$ tag:




In the OUTPUT tab, choose the destination of your package and select Differential as the package type:




You can check the summary of the export on your left, and verify the settings of your package. As soon as you are ready, click on the MAKE IMF button.

IV. Import and Q.C of the supplemental version

As soon as your supplemental version has been exported, you can import it back into MIST to check that everything is correct.

From your current project you can import the new package version of your IMF from the Library ( `F2` ).

In the CONTENT tab, we can see all metadata of our package.
Track files written in red indicate the absence of media in the package. This is normal because it is an additional version containing only the new assets specific to the VF. The missing ones are those related to the OV. To control a VF, you must first import the related OV.




This will not be necessary in our example because the OV is already existing in our project.

We advise you to launch a validation test from the VALIDATION tab in order to check the integrity and the application used by your IMF. 

If your two IMF packages are in the same project, you can toggle between them using the composition drop-down menu into the timeline:






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