Deliverables

File- and clip-based workflows
Managing near-set work can be an exacting task, encompassing verification, backup, sound sync, color correction, creation of dailies, archival, and many other critical production functions. Fortunately, the production of dailies from ARRI cameras is no more complicated in an ACES workflow than it would be in a traditional ARRI workflow. These pages will limit themselves to a discussion of dailies for delivery to editorial (or other distribution as per the needs of the production).

File-based ACES dailies workflows
ACES can be used in file-based workflows with ARRIRAW files arriving from the set, accompanied by any on-set color correction information (note that ARRI Look Files are not supported for use in ACES workflows). The illustration below shows a Codex Vault that processes Capture Drive cartridges arriving from the set, producing ARRIRAW files (.ari files). These .ari files would be converted to ACES by a near-set system (here, a Colorfront OSD system), the on-set color correction information — probably conveyed as an ASC CDL file — would be applied, and the result would be combined first with any show look, then with the standard ACES output transform. In this manner, the OSD system can create dailies for Editorial with the look and any on-set color corrections "baked in".

The OSD system also creates ACES images packaged in OpenEXR files for Visual Effects. These files are accompanied by "sidecar" files carrying any show look or on-set color correction, so that Visual Effects can preview their composites using the same transforms used by on-set or near-set creative staff.

Though this illustration has shown ARRIRAW being delivered as individual files to the OSD system, the workflow pertains equally well to ARRIRAW wrapped in MXF as produced by an ALEXA Mini.

The configuration given is illustrative; many others are possible, including direct production of deliverables from the Codex Vault, if that is the production’s preferred workflow.

Clip-based ACES dailies workflow
ACES can also be used in clip-based workflows where the scene was captured to a memory card in clip format, either as a ProRes or DNxHD clip from an ALEXA, or a ProRes clip from an AMIRA. The only constraint is that the content must have been captured using a Log C "gamma".

In this type of workflow, typically a single station is used to convert the captured Log C to ACES imagery, to apply any desired on-set grade and/or show look, and to apply that color correction and the ACES output transform to produce dailies for Editorial. For shots with visual effects, the station also makes ACES OpenEXR files for the Visual Effects artists. The artists are also provided with any on-set grading information and show look, so that any review of their material preserves the creative decisions made upstream.

Specific deliverable file types

Camera original ARRIRAW, ProRes and DNxHD
These should be cataloged and archived as would be done for a non-ACES show. Just as ARRIRAW processing has improved through the years, so similarly may the process of converting camera original content into ACES imagery and metadata; careful saving of the original files or clips can allow improved ACES processing in the future.

And if for any reason the production reverts to a more traditional ARRI workflow, it is the saved camera originals that will make that possible.

ACES container files (constrained OpenEXR)
ACES container files should be the primary deliverable for VFX work. An ACES container file is a 16-bit OpenEXR file containing not just the image but also the metadata that distinguishes an ACES-containing OpenEXR file from some other type of OpenEXR file.

ACES container files contain scene-referred data and should not incorporate any Look file effects.

Note that at the present time the ACES container specification only allows for uncompressed OpenEXR files to hold image data and metadata.

ProRes and DNxHD with "baked-in" color for Editorial
As few editorial departments can process the 16-bit OpenEXR images that will be used in the finishing suite, they will need to be provided with the same type of deliverables that they are accustomed to handling today — with the ACES output transform "baked-in".

If ASC CDL was used on-set or near-set on ACESproxy data as part of creative direction, then the effects of the ASC CDL should also be "baked-in" to the delivered dailies. Note that the ASC CDL is intended to work on ACESproxy or ACEScc data, not ACES data, so ACES dailies systems will briefly transform ACES data into ACESproxy or ACEScc, apply the CDL, and transform the result back to ACES.

It is also worth noting that much pain can be avoided at the end of the production if editorial monitors are calibrated according to the same standards used in visual effects and in digital finishing. By default, ARRI tools assume images they produce will be shown on monitors calibrated for Rec. 709 primaries, a Rec. 709 [D65] white point, and a 2.4 gamma response.

The variety of grades and looks

ACES does not mandate a particular workflow, but there is a fairly common ACES-based workflow that is flexible enough to meet most production needs. In this workflow, there are four points at which the color values in the captured scene can be changed for creative or for technical reasons: in a show look; in an on-set grade; in a VFX pre-grade; and in the final DI grade. Again, this is not a formal recommendation from the ACES development team, and even when adopted, each step is optional (though only live broadcast is likely to omit the final DI grade). If the workflow sounds familiar, it is because this type of workflow was established for high-end VFX-heavy productions long before ACES was developed.

Looks
Looks are color changes that are applied uniformly across the captured frame, and commonly are applied to many if not all shots in a production. An example look might be one emulating a particular film stock as developed and printed by a particular lab. Looks are typically developed during pre-production by the cinematographer and DIT, with input from other creative staff -- for example, the final DI colorist is often involved in look development.

Technically speaking, looks are applied to data in the linear ACES color space. For looks analytically derived from physical measurements (as would be the case for the print film emulation mentioned above) this causes no difficulty, but a linear space is not particularly colorist-friendly. So looks developed interactively by colorists are often developed in a colorist-friendly color space like ACEScc, and wrapped transparently in ACES-to-ACEScc and ACEScc-to-ACES transformations.

On-set grades
On-set grading is, typically, the application of ASC CDL operations — slope, offset, power and saturation changes — uniformly across the frame to log-encoded ACESproxy data either on-set during the composition of a shot, or shortly after the shot is captured in near-set dailies production. (In this sense, on-set grading is something of a misnomer; it happens as much near-set as on-set.) On-set grades are applied before any look is applied.

VFX pre-grades
Pre-grades are for shot-specific overall changes, typically to deal with uncompensated changes in illuminant over long periods of time. More detail on pre-grading is available in the post-production section, though it is worth noting here that the artists using the pre-graded plates should be provided with the on-set grades as well.

DI grade
The final DI grade is the last opportunity for creative change to the look of the image prior to distribution. More detail on the final DI grade is available in the post-production section, though it is worth noting here that the final DI colorist should be provided with the on-set grade, where it may be used as a starting-point grade, or at least as a historical reference.

Metadata

ARRI camera output is metadata-rich. When converting ARRI camera output to ACES there are several options for preserving metadata.

ARRI ALEXA cameras
The ALEXA can produce three types of output: ARRIRAW files (or from the ALEXA Mini, ARRIRAW clips wrapped in MXF), ProRes or DNxHD clips, and/or an HD-SDI video signal.

For ARRIRAW-based workflows, the maximum amount of metadata is carried over to the ACES container file when ARRI’s two ARRIRAW conversion programs are used — either the ARRIRAW Converter (ARC) application, or the ARC_CMD command-line tool. These tools fill in from the ARRIRAW file all the required metadata to make the OpenEXR file a compliant ACES container, and embed much more optional ACES and ARRI-specific metadata as well. For details on what metadata is embedded, see the ARRI metadata documentation. For details on how to use the ARRIRAW Converter application, see the Tools section below.

Alternatively, for Codex-based ARRIRAW workflows, ACES-containing OpenEXR files can be generated from the downloaded Capture Drive at the same time as the ARRIRAW files themselves. The Tools tab of this section shows how to use the Codex Vault UI to generate OpenEXR files as well as ARRIRAW files. (The ARRIRAW files should always be produced and saved even in an ACES-based workflow, as they offer the highest-quality archiving of the captured imagery.)

Log C HD-SDI output can be captured and later converted to ACES OpenEXR files as desired, using a third-party tool such as Blackmagic Design’s Resolve or Colorfront’s OSD. ACESproxy HD-SDI output can not be converted to ACES OpenEXR files, however, nor can Rec. 709 HD-SDI output.

ARRI AMIRA camera
For the AMIRA, ProRes Log C or MXF/ARRIRAW clips can be brought into ACES. For on-set or near-set dailies creation, Log C clips can be converted to ProRes Rec709 or DNxHD Rec709 clips using tools such as those described above.


Tools

ARRIRAW Converter
ARRIRAW files are the highest-quality path to ACES imagery when capturing a scene with ARRI cameras. The reference conversion tool is ARRI’s freely-downloadable ARRIRAW converter. (Users not already having the ARRIRAW Converter can download it here.) Other portions of ARRI’s website describe its operation, but there are four key settings in the Render Settings "Format & Color Space" tab that must be correctly set to producing ACES files.

  • "OpenEXR" should be selected in the pull-down "File Format" menu
  • "Scene Lin" should be selected in the pull-down "Encoding" menu
  • "Uncompressed" should be selected in the pull-down "Compression" menu
  • "SceneLin. - ACES" should be selected in the pull-down "Color Space" menu

A Render Settings panel correctly configured for producing OpenEXR is shown below.

ARC_CMD
For scripted batch use, the reference conversion from ARRIRAW to ACES-containing OpenEXR is ARRI’s freely-downloadable ARC_CMD command-line tool. This tool is controlled by an XML file whose name is indicated in the command invocation. The key parameters and their values are:

  • colorspace — this parameter should have the value "ACES"
  • format — this parameter should have the value "exr"

Codex Production Suite

The Codex Production Suite allows for the creation of OpenEXR files that conform to the ACES Container Specification, and (given appropriate 3D LUTs) of dailies embodying the default ACES rendering. It also provides for taking upstream ASC CDL information and applying those ASC CDL operations in the ACES processing pipeline in the proper context, that is, in the ACEScc color space.

Producing ACES-containing OpenEXR files
First, make sure that there is an ACES OpenEXR target deliverable defined in the Project > Deliverables section of the Codex Production Suite UI. It should be defined something like this:

Although the contents of "Roll transform" may be set to some production-specific value. Next, make sure that this deliverable is in the list of deliverables being produced by the VFS, as defined in Project > VFS:

... with the various pathnames and filters set appropriately for the production.

Producing dailies embodying the ACES output transform
Applying the ACES output transform to ARRI Log C data means transforming the image from Log C to ACES, then rendering the ACES image data for a particular display. This set of three transforms can be approximated with a 3D LUT.

The example below shows a deliverable configured to produce high-quality ProRes dailies by using a hypothetical 3D LUT that approximates taking V3 Log C data, turning it into ACES data, and running it through the Reference Rendering Transform (RRT) and an Output Device Transform (ODT) suitable for a "Rec 709" monitor.

As of the 4.0 release of the Codex Production Suite, the Add button next to the Lut field allows for one to add in ASC CDL processing with that processing applied (correctly) within the ACEScc color space. That button also allows for the application of a Look Modification Transform (LMT) immediately after the ASC CDL application.

Resolve 12
Resolve 12 can be used to quickly process ACES OpenEXR sequences, ARRIRAW sequences or ProRes or DNxHD clips (assuming the clips were created with Log C "REC processing") into dailies deliverables, as follows:

  • Create a new project in Resolve and in the Project Settings’ "Master Project Settings" section, and after setting the appropriate values for image size, frame rate and so on, set "Color science" to "ACEScc" and set the ACES version to "ACES 1.0."

In the Project Settings’ "Color Management" section, set "ACES IDT" to "Alexa". Be sure the ACES ODT is set to "Rec.709".

  • Browse and bring in ARRIRAW, or ProRes Log C, or MXF Log C media into your Resolve project
  • Create a timeline and drag the media onto it.
  • Skip the Color correction portion of Resolve’s UI entirely.
  • In the "Deliver" portion of the UI, set the "Video Format" to your desired output format (QuickTime, DNxHD, etc.) and set the "Codec" similarly. In the example below the Format is set to produce QuickTime dailies encoded with the Apple ProRes 422 HQ codec.
  • Browse to or create a location into which the OpenEXR files would be rendered.
  • Embody the current settings as a render job with "Add to Render Queue", and render the clips to produce dailies with "Start Render".

Resolve 12 can also be used to produce OpenEXR deliverables from captured ARRIRAW sequences, or from ProRes Log C or DNxHD Log C clips. To do so, one would proceed as follows:

  • Create a new project in Resolve and in the Project Settings’ "Master Project Settings" section, and after setting the appropriate values for image size, frame rate and so on, set "Color science" to "ACEScc" and set the ACES version to "ACES 1.0."

Note that these settings are identical to those used for dailies deliverables.

  • In the Project Settings’ "Color Management" section, set "ACES IDT" to "Alexa". Be sure the ACES ODT is set to "No ODT". 
  • Browse and bring in ARRIRAW, or ProRes Log C, or DNxHD Log C media into your Resolve project
  • Create a timeline and drag the media onto it.
  • Skip the Color correction portion of Resolve’s UI entirely.
  • In the "Deliver" portion of the UI, set the "Video Format" to "EXR", the "Codec" to "RGB half (no compression)"
  • Browse to or create a location into which the OpenEXR files would be rendered.
  • Embody the current settings as a render job with "Add to Render Queue", and render the clips to produce OpenEXR frames with "Start Render".

Colorfront OSD

Modern versions of Colorfront OSD provide templates that allow straightforward production of both dailies for Editorial and OpenEXR plates for visual effects. When an ACES-based project is created, ACES support should be specified as a creation parameter, as shown below.

The parameters of the resulting chain of processing nodes are preset for production of ACES dailies, as shown for the first "result" in the processing chain below (including ASC CDL application in the ACEScc space).

The second result, producing OpenEXR-containing ACES files, was manually added.