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HDR Mastering using Dolby Vision

HDR Mastering using Dolby Vision

 

Integrated Content Mapping V2.9 and V4.0 - eCMU is no longer supported

 

Dolby Vision - License

Access to the Trim features in the Integrated CM versions requires a license from Dolby.  

The license file should be renamed to “DolbyCM_License.bin” and placed in the c:\xxxxx\License directory.

 

Any attempt at altering the license will invalidate it.

To purchase a DV Mastering license, please check this FAQ . To learn more about Best Practices, please check this FAQ .
 

 


Overview
 

A Dolby Vision delivery consists of a High Dynamic Range PQ master, graded on a mastering monitor of no less than 1000 nits. It also has an XML file containing scene-by-scene metadata to optimize playback on displays of different brightness.

It uses the ST2084 PQ curve but requires a display with Dolby Vision licensed firmware to play back correctly. LG, Sony, and Vizio currently offer Dolby Vision licensed consumer displays.

The workflow entails the grading of the master HDR version on the brightest display available, and then creating a scene-by-scene trim metadata for specific target monitors and projectors.

The mapping of the HDR content to the target display is based on analysis of the graded images and then mapping the HDR signal to a different brightness. At this point, the mapping can be refined by manually trimming the values using a specific set of tools and parameters that are provided by Dolby.

A monitor/projector capable of displaying material with the ST2084 PQ EOTF is required to grade Dolby Vision Master and deliverables.

Dolby does recommend using the highest quality displays available when creating Dolby Vision content. As a general guideline, Dolby recommends the following minimum image quality specifications for an HDR grading/mastering display:

  • 1,000-nit peak luminance
  • 200,000:1 contrast ratio
  • DCI-P3 Color Gamut
  • ST.2084 (PQ) EOTF
  • D65 Whitepoint

Here are some examples of monitors that match Dolby recommendations:
 

  • Dolby Pulsar 4000 nits - not commercially available, but can be provided by Dolby on request

  • Dolby Maui  2000 nits - not commercially available,  but can be provided by Dolby on request

  • Sony BVM X310 and HX310 1000 nits - available from Sony

  • EIZO Prominence CG3146

  • Flanders XM310K
  • Flanders XMP550
  • Flanders XM311K
  • TV Logic LUM-310

The output of a Dolby Vision session depends on the requirements. For a Dolby Vision delivery, there will be two parts. The first part is the HDR master sequence encoded and exported as 16 Bit Tiff or EXR files. The files are created with the PQ curve as part of the rendered images.

The other component is the Dolby Vision XML file that contains metadata about the project, image analysis, and trim data for every additional target display.

This XML is used to create different masters and also dynamically map the content on Dolby Vision enabled displays based on the additional target display trim data.

 


Approaches to Dolby Vision mastering

 

There are different ways to approach Dolby Vision mastering

 

  • Work on the original project with the graded timeline - complete the HDR grade, and turn on the Dolby content mapping option. Analyse and then do the SDR trim (Dolby Dual view is not required but can be useful).

  • Grade the HDR and the SDR version at the same time, analyzing and trimming as you go. Dolby Dual view is required in this case - there is a danger of changing the HDR grade and not re-analyzing the material afterward - this will cause unexpected results for the trims.

  • Dolby Vision trims are performed on a mixed-down master that is scene detected or cut up with an EDL - this workflow makes changes to the original HDR grade difficult if needed to enhance the SDR version.

 


Content mapping options

Nucoda and Phoenix have support for Dolby Vision, allowing for image analysis and metadata generation for trim passes, the export of Dolby Vision XML files, or rendering the trim pass results as a new master.

A Dolby license is required to unlock the trimming functions of the software content mapping option.

Dolby Vision analysis passes and mapping can be performed without a license, but you are unable to trim content.

Internal Content Mapping - Dolby Vision v2.9 and  v4.0

  • The  Internal Content Mapping option allows Dolby Vision mapping and trim functions to be applied and viewed using an integrated version of the content mapping algorithms. 

  • Dolby Dual view option (Kona 4/5 required, BMD cards will have the ability to do it in a future update) allows viewing the HDR and SDR version simultaneously to allow trims to the HDR version to improve mapping to SDR if required.

  • Trimmed deliverables can be exported directly from the timeline without the need for any other tools.

External Content Mapping unit (eCMU) - v2.9 only (Legacy)

  • The eCMU can be purchased only from Dolby. It is connected via SDI and it allows content mapping and trims to be displayed on the selected target display monitor, connected to the eCMU.

  • Deliverables are generated using the Dolby Vision XML and cm_offline tool available from Dolby.

  • Contact Dolby directly for information on how to obtain the hardware eCMU

 

Project settings

 

Full Range

  • SDI Output set to (0 - 1023)
  • 16-bit or Half (recommended) - 10-bit is possible but not recommended.

 

ACES Project

  • SDI Output set to (0-1023)
  • Add two identical output formats with the same PQ Output Transforms - typically P3D65 1000 nit depending on your mastering monitor
  • On the second output format turn on “Apply LUT” - required when using Internal Content Mapping to ensure correct analysis.
  • Dolby Vision content mapping can be enabled before or after the main grade is performed.

 

Choose between v2.9 or v4.0 - Make sure which is the correct version for your production

 

 

Once inside the project you will notice that the two Dolby buttons in the Library interface are active, this is where the mastering display is selected.

 

Library Buttons.PNG

 

On the timeline, you will see that every clip has a new layer added after the Master layer - this is the Dolby Content mapping layer.

Clips with a composite effect will not have this layer as they are seen as part of the clip they are composited over on the layer below. 

 

Monitoring and Video IO / Setup Menu- Dual Dolby Display

 

  • The link should be set to 1 for using Dolby Dual (3G-DL is required)

  • LevelB-DL

  • The SDI I/O Mode must be set to RGB 444 12-bit (no HFR frame rates) 

  • Ensure the Monitor format is set to 1080p for Dual Dolby with  UHD.

 

Dolby Dual output 

 

Using Dolby Dual mode for comparisons: The Compare mode is visible on both the HDR mastering and iCMU monitors

 

 

 


Setting up the Mastering display and Trim Target
 

Using the eCMU - only visible with  Dolby Vision 2.9 project - Legacy workflow, not recommended

 

Dolby - Configure Dolby CMU.png

 

      ...Config DolbyCM button in the Library

  • There is an option to turn on Integrated CM - for the hardware eCMU leave this turned off
     

  • In hardware mode with an eCMU connected, select the “Attached eCMUs”  button - this will show the name of all currently connected eCMUs - there is also the option to rediscover eCMUs.

    Choosing the Project eCMU button will show a list of eCMUs previously associated with that project. Any hardware eCMU that had been connected and later disconnected, will be remembered, along with the eCMU mastering settings.
     

  • The Master Display dropdown has a list of mastering monitors currently supported - options will change as the product is updated by Dolby.
     

  • Use this selection to select the mastering monitor for the HDR version. The mastering monitor must match the monitor that the HDR version was graded and the image color space to ensure correct analysis values.
     

  • Select a Target Display in the right column. This is to select the trim target monitor connected to the eCMU. The list includes displays that are commonly used. The target is linked to the Target display in the Dolby Mapping tool interface but must be updated in this menu for the hardware eCMU.
     

  • The target display list is dynamic - it is read from a and available targets will depend on the version of eCMU firmware.

  • Currently, supported firmware versions are 2.6.3 and 3.0.2

 


 

Set up Integrated Content Mapping v2.9   

 

 

 

     ...Config DolbyCM button in the Library

  • The Master Display dropdown has a list of mastering monitors currently supported - options will change as the product is updated by Dolby.
     

  • The version of the CM Config is shown in the interface - the current required version is 1.1 - the correct version is provided with the installer - the v1.0 shown is due to a bug in the current binary.
     

  • Use this selection to select the mastering monitor for the HDR version. The mastering monitor must match the nit value and color space that the master version was graded on to ensure correct analysis values.
     

  • Select a Target Display in the right column. This is to select the trim target monitor connected. The list includes displays that are commonly used. The target is linked to the Target display in the Dolby Mapping tool interface.
     

  • The target display list is dynamic - they are read from the CM Config file and available targets will depend on the version of the software being run. The config file can be updated by the user but should only be done on instruction from Dolby.
     

     

    For 2.9  the mastering monitor color space will affect the analysis method, so it is important to match the content color space to the correct Master monitor setting.

     


 

  Integrated Content Mapping v4.0

 

  

 

 ...Config DolbyCM button in the Library

 

  • The Master Display dropdown has a list of mastering monitors currently supported - options will change as the product is updated by Dolby.

  • Use this selection to select the mastering monitor for the HDR version. The mastering monitor must match the monitor that the HDR version was graded in to ensure correct analysis values.

  • Select a Target Display in the right column. This is to select the trim target monitor. The list includes displays that are commonly used. The target is linked to the Target display in the Dolby Mapping tool interface.

  • The target display list is dynamic - they are read from the CM Config file and available targets will depend on the version of software being run. The config file can be updated by the user but should only be done on instruction from Dolby.

  • Custom Mastering and Target monitors can be created and stored when using v4.0 CM;  multiple Presets can be stored but only one custom monitor can ever be used at a time. During creation, it is recommended to cut and paste the required values. Invalid entries will show up as red in the interface.
     


 

Image Analysis

 

The analysis pass works by processing each frame of the content, using the project timeline to generate metadata for each shot. At this point, the metadata consists of just three numbers, a minimum, maximum, and average brightness for each shot. 

The analysis has to process every frame in the sequence and might take some time; HD is faster than UHD.

You can re-analyze single or multiple shots by selecting them on the timeline

Use single-frame analysis when there are sudden changes in the shot like headlights flashing to prevent the flash from affecting the rest of the clip.

Scene analysis is done once the analysis has been performed - select multiple clips and select scene analysis to get an analysis average for the scene.

 

 Things to keep in mind

  • Ensure that the Image Format setting matches the content being analyzed, the setting should match the picture content and exclude any black bars. It's possible to add new formats, please email support@filmworkz.com and we will help you out.

  • The image format setting will also be used to correctly mask the image when trimming, preventing the masked areas of the image from being processed.

  • Any composited images will be analyzed and the result displayed on the bottom layer.
     

Clips with the composite effect will not have the Dolby Trim effect, but the clip below it will, the analysis on the clip below will be the result of the composite. Please turn off tracks with titles or composites during the XML export.

Use Pg Up / Down to access the track below.

 

 
  • The analysis will be incorrect if the material does not have the PQ EOTF applied. 

  • If you are in an ACES project ensure the chosen output format has “Apply LUT” turned on in the project settings and that the Output Transform is a PQ transform.

  • For 2.9,  the mastering monitor color space will affect the analysis, so it is important to choose the correct Master monitor setting.

  • Clips that have not been analyzed will display purple above the clip in the timeline ribbon and will prevent an XML from being generated

 

By default the Analyze button is turned off - it is global, so turning it on turns it on for all clips

Once the HDR Master grade has been completed, the content must be prepared for the trim pass to create the other required deliverables. 

 

 

Concerning titles or overlays during the analysis and trim phase

  •  If titles are being added make sure they are mapped to PQ and that the levels are correct when viewed on a mastering monitor, 150 to 250 nits is a good start.
  • In-picture titles can affect the analysis, but normally it is so minimal as to not make a difference to the trims, 
  • If there are already titles applied you may consider analyzing a single frame on the clip that has no title showing.
  • For white-on-black titles, use a single frame analysis and apply it to all black and white title cards.

Trim controls

  • LGG controls are mapped to the rings and balls

  • Dynamics can be used to easily animate between different trim on the same clip

 
  • a 100-nit version is a requirement as a starting point to calculate other trim versions.

  • Once you have created the 100-nit version you need to use the Interpolate function to create the 600-nit and 1000-nit versions., you can then refine those trims as needed.

Recalling, resetting, and bypassing trim values 

  • To recall trim values between clips, use the recall trim button on the tool screen on the Precision.
    Do not use the normal Recall button on the Precision or Tangent panels as this will recall the whole   Dolby Vision effect including analysis and trims

  • Use the Reset trims button to reset the trims - for 4.0 there are separate resets for LGG and Secondaries

  • Use bypass to bypass LGG and color tools - for 4.0 there is also a bypass for secondaries.

  • When recalling ensure that the Content Mapping layer is selected as the source

  • When using the Precision, you can also use the Turbine button to recall trims, and  a long press to reset trims

 
  • Please note: In 100-nit trims, the Tone Detail option cannot be edited

 

Precision Panel and GUI

All controls are available in the Tangent mapper for mapping to the Element and ARC panel

 

 Precision v2.9 trim menus

 

  GUI v2.9 trim menu - LGG and Colour trims 

 

 

 Precision v4.0 trim menus 

 

 GUI v4.0 trim menu 1/2 - LGG and Colour Trims - Contrast Bias and Highlight Clipping

 

 GUI v4.0 trim menu 2/2 - Secondaries - 6 Vector Hues and Saturation

 


Creating trim versions for other displays

 

Only once the HDR master grade is complete the timeline can be analyzed to allow content mapping.

After analysis, the colorist will take a view as to whether or not the resultant image is the best representation of the image on the Trim target monitor and will create shot-by-shot trims

 

Interpolate new trims

 
  • a 100-nit version is a requirement as a starting point to calculate other trim versions. Cinema trims can be also created, but they're completely separate. Please see this FAQ for more information.

  • Once you have created the 100-nit version you need to use the Interpolate function to create the 600-nit and 1000-nit versions., you can then refine those trims as needed.

  • Interpolation will only be possible if at least one other trim exists.

  • Select the required new trim target.

  • Select all the clips on the timeline

  • Press the Interpolate button - to calculate the new settings based on the currently available trims.

  • In some cases, a Trim with 0-values is needed to avoid results that can be brighter than the highest nit version. To quickly add 0 to trims, select the desired trim value and click on the "Add Zero Trim" button.

New " Add Zero Trim" button

Creating the Dolby Vision XML

 

...export Dolby CM button in the library 

 

  • Select a destination and name for the XML file that is being exported.
  • Select the XML version
  • Any trims or changes made to the master or the trim targets will require a re-export of the XML.
  • For any titles that were added on separate tracks please turn off the title tracks before exporting. Only active tracks will be included in the XML - overlapping clips are not supported, and the export will be a top-down mixdown.
  • During the export process, the XML will be validated - if there are any errors the user is notified with a popup dialog with information on the problem. Selecting an existing XML and pressing the Validate button will validate the XML
  • A file validation file is also written when the XML is exported. the file has the same name as the XML with _validation appended to the name. This file will contain the dialog information in case of a failure.
     

Exporting images of the current trim as SD or HDR  master

 

export-xml-trimmed.png

...export files button in the library
 

  • Ensure the Dolby CM button is selected - this option is not available in External eCMU mode.

  • Choose the export option for the trimmed master files and export.

  • Turning the Dolby CM button will export the HDR master.

  • Export 16-Bit Tiff files for Dolby Vision delivery

 


Precision controls for Dolby Vision (from 2018.3)

 

A new mode has been added to the Precision Panel that will allow users to use the familiar Master Reset, Bypass All, Recall, and Append buttons on the panel while doing Dolby Trims.
In a Dolby project, press the Turbine button, this will place the layer focus on the Dolby Content Mapping effect and place the panel in Dolby group mode, in this mode the following buttons will have their functions changed as follows:

 

KeyCommand

MReset Reset trim values - LGG and Colour
Ctrl + MReset  Reset Secondaries (4.0)
Hold MReset Reset Analysis
Recall Recall trim values - LGG and Colour
Ctrl + Recall Recall Secondaries (4.0)
Hold Recall Recall Analysis
Append Analyse single frame
Ctrl + Append Analyse Scene Average (use after selecting multiple shots in a scene)
Bypass All   Bypass all trim values - LGG, Colour (2.9), and Secondaries (4.0)
Ctrl + Bypass Bypass Colour and LGG
Hold Bypass Bypass Secondaries (4.0)
P - Recall trim values Recall trim values - LGG and Colour
Hold P Reset Trim

 

We recommend you set the Layer focus on shot change to “Match between shots” when working in Dolby.Trim - It is available by right-clicking on the timeline and choosing Effect Focus -> Match Between Shots

Bypassing Dolby Vision mapping

  • Selecting this option will turn the content mapping on and off

  • Please note that this will affect the rendered output.    

 

Using comparison modes - applies to Integrated CM only

  • In Dual Dolby mode using the compare tool will not apply the content mapping to the comparison Source, meaning that you can compare a Rec.709 version of an original with the Dolby Vision trimmed Rec.709 master.
     

  • This does mean that you are currently unable to compare to the trimmed version
     (this will be addressed in a future update)

 


Connecting the eCMU (Legacy)

 

The eCMU is designed to be a “headless” box, meaning it is designed to sit on a rack in the server room and operate with minimum interaction.

It can be useful to connect a keyboard and monitor to set up initial networking options. 

 

  • Plug a USB keyboard into a USB slot. There is no need for a mouse, as there is no GUI

  • Connect a monitor to the VGA port. Do NOT connect the monitor to the graphics card on the eCMU

  • Please follow the eCMU setup instruction in the eCMU Manual

 

 eCMU - SDI and networking  (Kona 4/5 only)

 

 


SDI output from the AJA Kona

 

 

  • The SDI I/O Mode must be set to RGB 444 12-bit to operate the eCMU

  • Note: UHD -  12-bit is only available using the Quadrant mode, not 2Si

  • The SDI output should be connected to both the mastering monitor and the eCMU input, it is possible to use a looped output from the monitor to the eCMU.

  • Ensure that the Monitoring format is set to HD1080p or UHD depending on the eCMU model, and convert set to None or Fit. (see image above)

  • The eCMU supports 1080P and UHD formats depending on the model.

  • HD Connectivity with the eCMU is recommended to be 3G Level B-DL - 1 link.

  • The eCMU will automatically configure the output SDI interface to match the input SDI interface.

  • Since the workstation IP Address is encoded and sent to the eCMU via SDI, please ensure that there is an image on the screen or has a composition open to allow discovery of the eCMU. Please see the eCMU User Manual for setup instructions.

Ethernet connection between the workstation and the eCMU
   

  • The ethernet address of the Nucoda or Phoenix workstation is encoded in the SDI video stream to the eCMU and the eCMU then connects via the ethernet port.

  • You will have to add a Windows firewall exception for the port communicating with the eCMU or turn off the Windows firewall completely.

  • You can control and reset the eCMU by loading a web browser and entering the eCMU IP address in the browser.

  • Please add the workstation IP address to the general.prefs file here:

c:\xxxx\20xx_x\root\Users\All Users\general.prefs

  • The option is right at the bottom of the file:

ForceIPAddress "Nucoda/Phoenix workstation IP"

 

Most common reasons for not detecting the eCMU:
 

  1. Make sure you can ping the eCMU and connect via a web browser

  2. The Windows Firewall is on

  3. The video settings are not 12-bit 444

  4. The monitor format is set to Follow Project and not 1080p or UHD

  5. Inactive timeline - make sure there is video going to the monitor

  6. In the browser check that the input signal matches the output and is valid

  7. The Web interface, available for the eCMU via the browser and the eCMU IP address, is a very useful source of information.

  8. Remember to check the eCMU web interface for error messages if something does not seem to be working as expected

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