Create an Original Version IMF in Dolby Vision

Create an Original Version IMF in Dolby Vision

The purpose of this tutorial is to introduce you to the main steps of making an Original Version package in Dolby Vision according to Netflix specifications. For this tutorial, we will use existing Dolby Vision metadata.

For details on how to perform certain operations, please refer to MIST user manual or other articles of this Knowledge Base.

In this tutorial we have the following sources:
  1. -A video track in DPX 16 bits RGB UHD P3D65 24fps.
  2. -A stereo audio track in PCM 24bits 48kHz wave file.
  3. -A 5.1 audio track in PCM 24bits 48kHz wave file.
  4. -A Dolby Vision MDF XML file (Dolby Vision metadata file).
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. Create a new project

Click  NEW  from the MIST main menu to create a new project. This new project will be the Original Version of our IMF package for Netflix:

II. Import files

When the project is created, from the timeline, we can browse through the Windows file browser to drag and drop the media into the Quick Library.

If you are importing an image sequence that does not have a frame rate metadata, it must be set before importing the media into the Library. To do this, in Project Settings, go to the Media tab and change the Default Frame Rate:

III. Place the media on the timeline

When you have finished importing the media necessary for the project, you can access the Timeline module ( `F3` ) to place the elements on it. 

Depending on the settings you set for the audio configuration in the Project  ( `F1`) properties, an audio layout already exists in the timeline. If you want to change it, you can delete it by right clicking on it and then delete

In our case, the 5.1 is already present. We need to add an audio layout for our stereo tracks. To do this, click the A + button at the top left of the timeline and select Stereo:

Select your media from the Quick Library and drag them to the timeline to place them on the desired track. If you use the copy / paste function, remember that the media will move to the active track and at the playhead location:

If your audio layout is divided into individual tracks, select them in the desired order and hold down the left mouse button to drag them to the timeline and magnets to the mouse cursor. Right-click on the timeline to access the Composition Operations menu and select Replace Stacked at Cursor:

Once the media is in place, you have to define the duration of the composition. To do this, use the hotbox of the timeline with `Ctrl + right click`. From the Composition tab, select the desired method:

Do not forget to save your timeline regularly.

To check for sound on your audio tracks, you can still display the waveform audio via the Composition Operations menu ( `Alt+right click` ):

IV. Configure the composition settings

The composition setting corresponds to what will be our Composition Playlist in our future IMF package. It is very important to take the time to set it properly. 

To access the settings of the composition, right-click on the viewport then Settings:

General settings

In the General tab, name your composition. Unlike SDR versions, the use of HDR including Dolby Vision requires to be in Versioning mode:

Define the Active Area Aspect

The Active image area metadata is crucial and mandatory when using Dolby Vision technology.

You must set this setting in the OUTPUT tab and in the Active Area Aspect drop-down menu, select the active area of your image, taking care to exclude blankings.

If you are importing Dolby Vision metadata, make sure that your Active Area Aspect settings of your composition, match those used in your existing Dolby Vision MDF file.

For more information, please refer to the manual.

Color Management System

After setting the output settings in the OUTPUT tab, you must configure your color pipeline from the CMS tab. You can select NATIVE if you have PQ rec2020 or P3 sources:

Also, be sure that no LUT has been applied on your clip into the GRADE panel ( `F9`):

If MTCMS is selected, you need to define the working color space and the transfer curve of your composition. Then in the SOURCE tab for the clips (in GRADE mode), select the source parameters. For Dolby Vision, the Transfer Response Curve must be set as PQ. The working color space can be either Rec2020 or P3. Also you can setup the Luminance Levels for minimum and maximum brightness.

For more information on the operation of the CMS in MIST, please refer to the user manual.

Because our content is in P3D65, we will use the NATIVE color system.

Remember to enable Dolby Vision technology by selecting it from the Dynamic Mapping drop-down menu. Otherwise, you will not be able to read or perform operations related to Dolby Vision:

According to the Netflix specifications, it is essential to correctly fill in the Mastering Display information, also known as ST-2086.

To do this, in the MASTERING DISPLAY tab of the CMS, select an existing setting or customize your own monitor settings. These settings provide information on the monitoring conditions in which the mastering was performed:

The selected mastering display must match the one used in the Dolby Vision metadata file. You can read this metadata by opening the file with a text editor. 

V. Importing Dolby Vision metadata

Now that your composition is set and your media is placed, we can import Dolby Vision metadata. Do not trim your clip before importing the metadata. Otherwise, your clip will no longer match the time in the metadata, and you will not be able to import your metadata successfully.

There are two ways to import Dolby Vision metadata to content. Each responding to a situation of its own.

If the In and Out points of your edit clips match those used when generating Dolby Vision metadata, you can import the MDF file via the IMPORT button at the bottom left of the timeline:

This saves you from having to import MDFs clip by clip.

However, if the composition has been exported in one block and you need to "split" this block using the Dolby Vision metadata, you need to import the metadata via the Clips operations menu:

In both cases, the duration of your content must match that of the Dolby Vision metadata you want to import.

For this tutorial, we will use the second method because of our single image sequence.

When the import window appears, select Dolby Vision MDF from the File Type drop-down menu and the XML you want to import and click OK:

VI. Inspecting Dolby Vision metadata

Before accessing the IMF export window, you can check the presence of metadata into the timeline. A color bar appears under each clip having metadata: 

If there is no bar (and the dynamic tone mapping is well selected), it means that your content has no metadata or that the values have been reset. 

it is essential that each clip has its Images Characteristics including black clips. If this information is missing on a clip, MIST will inform you of the non-validity of the metadata when exporting the IMF. No gap is allowed.
You will then have to either import the MDF file to the clip in question, or analyze the clip by clicking on it and then accessing the HDR analysis tool (F6). To see if the clip has been analyzed you can read the IC values that appear in the DMCVT Metadata Inspector ( `Shift + D` ):

When using the CMU, it is possible to toggle target displays from the Dolby Vision grade panel ( `F9`) in order to check their respectives metadata:

For more information regarding the DMCVT Metadata Inspector and the Dolby Vision grade panel, please refer to the MIST user manual.

VII. Exporting an IMF in Dolby Vision

As soon as your timeline is ready to be exported, you can access the IMF export module using the IMF button at the bottom left of the timeline:

Once the IMF export module is displayed, select the template that meets the Netflix specification called Netflix HDR Dolby Vision:

We strongly advise you to take the time to make a tour of the settings before export. Gray settings are inaccessible due to the choice of the template. 

In the ESSENCE tab then VIDEO, we can see that the Dolby Vision metadata are checked to be exported.

It is therefore not necessary to check the Mastering Display box because this information is already included in the Dolby Vision metadata. Note that Dolby Vision metadata is embedded in the file. No sidecar is generated.

In order to gain processing speed don't forget to choose GPU engine.

Don't forget to check that the language of your audio layouts and the mapping of the audio channels are correct. For clarity, you can also rename your audio layout by changing the name in Title:

In the OUTPUT tab, when all previous settings and adjustments have been made, click the BROWSE button to set an export path.

It is highly advised to check the Force Reels Bounds box before exporting:
This option will allow you to have a single MXF video file by creating a single video segment without keeping the clips cuts. If the option is not checked, MIST will export an MXF video file for each Dolby Vision metadata cut. Given the number of possible cuts in a Dolby Vision editing, the management of such a package could become laborious in terms of time and manageability.

Click MAKE IMF as soon as you are ready to export.

Because we are exporting an Original Version, no other type of package or other method is available.

VIII. QC of the IMF package

Once the IMF is exported, we advise you to open it at least once before sending it. To do this you can import the IMF package as a new project from the main menu of MIST or import it into the existing project via the Library.

From the library, right click and select Import IMF:

When the IMF import panel opens, click the BROWSE button at the top right to select your package. As a result, the metadata is displayed in the CONTENTS tab and allows you to check the properties of your package:

You can see the presence of Dolby Vision metadata in the PHDR Global Metadata containing the mastering display information and the targets displays used.

In the VALIDATION tab, it is possible to perform tests to determine the integrity of the package and the applications to which it refers. Click on SELECT ALL then EXECUTE.

In our case, the failed tests relate to applications that are not relevant to our package. It is therefore normal. In addition, tests displaying a warning do not affect the proper functioning of the IMF but draw your attention to certain points:

By clicking SAVE, you will be able to export a PDF version of this test with more details about the test performed.

Now click on the PHOTON tab. This is a tool used by NETFLIX to validate packages. 

As soon as you are ready, you can import the package by clicking OK.

Back in our timeline, because of  the Force Reels Bounds option has been checked, we see that our video track contains only one clip. The white bar indicates that the clip is read-only.

By using the DMCVT metadata inspector as explained earlier, you can inspect the metadata without any additional operations.

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