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This article serves to cover what a Netflix branded production may encounter when having their content tested for potentially harmful flashes. 

 

Netflix Branded Animated content is currently the only content type tested for potentially harmful flashes. 

 

Please refer to the Netflix Branded Delivery Specification for the most up-to-date requirements around what kind of content must be tested for potentially harmful flashes. This information can be found in the Source Material Requirements section at the beginning of the document.

Key Terms

Photosensitivity - a medical condition where flashing lights or quickly changing color patterns in video content can trigger (conditions to be added, such as migraines, pending literature from The Epilepsy Foundation). Viewers who do not experience epilepsy can still be susceptible to effects of photosensitivity. 

Photosensitive Epilepsy (PSE) - a medical condition where flashing lights or quickly changing color patterns in video content can trigger epileptic seizures in some viewers. 

Potentially Harmful Flash - a series or sequence of luminance changes at a certain rate that may trigger seizures in some users. Specifics of the flash can be found in ITU BT-1702 specification

PSE Test - Software based scan test that interpolates video content and detects harmful flashes. 

FPA v__ - FPA stands for Flash Pattern Analysis.

Harding - Researcher Graham Harding, who co-Authored the white paper on Photosensitive Epilepsy. His name is commonly used for the testing that occurs to find potentially harmful flashes. Full paper linked here.

Testing Method

Prior to or during the Netflix delivery process, your content may be tested for Potentially Harmful Flashes. This can be done prior to delivery at your post facility via an automated QC software platform listed on the table below. Please email any completed PSE test reports to pto-specialists@netflix.com once completed.

 

Please note, software testing tools can only currently support Rec709 color space files, in standard dynamic range. If your content is HDR, a trim passed version will be subjected to this test. Standards for high dynamic range and Dolby Vision content are still being researched.

 

PSE testing may also occur during the QC/delivery phase on your content. Any failures of this test will be noted in the Asset QC report. 

 

Each will take a video file of your content, scan the video content, and output a report based on parameters set in the ITU Specification for Photosensitive Epilepsy Testing. If one or multiple sequences of frames contains flashes that are above the thresholds for potential harm, your content will be marked as failed. 

Testing Tools

There are several tools that can provide testing to the 1702-1 Specification, there was a recent update so it would be valuable to ensure that your system is using the most up to date PSE Version, if the PSE version isn't here, the tool is not considered compliant.

 

Company

Product Version(s)

PSE Version

Cambridge Research Systems

FPA Desktop V3.5 or later

FPA V3.4

FPA Server V3.0.0 or later

FPA UK Digital V0110 or later

Tektronix

Cerify V7.8.0 or later

FPA V3.4

Aurora V3.6 or later with FPA option

FPA V3.4

Interra

Baton V7.4 or later

ITU-R BT.1702 2018 (V1.0)

Vidcheck

Vidapps-PSE V1.0 or later

Vidcheck PSE V5.1

Vidchecker V8.0 or later

Vidfixer V8.0 or later

Cel-Soft

PSE-Check V2.410 or later

Cel-soft PSE V2.0

Reel-Check Solo V1.410 or later

Reel-Check SE V3.410 or later

Venera

Pulsar V4.3 and higher

FPA V3.4

EditShare

QScan One

Quales V1.1.0



What Can I Do If My Content Fails a PSE Test?

When your content has failed a PSE test, you should receive a PDF report that may look like this:

Screen_Shot_2020-09-30_at_7.57.38_AM.png

This cover page will specify the number of failures and frames affected, along with pertinent metadata about the file tested. 

 

The following pages of the PDF report will contain a detailed breakdown of the frames affected.

 

Now that you have your failed report, please loop in your Netflix Post contacts (both Post Manager and PT&O Specialist) to confer on what the best course of action will be.

 

Or PSE Test failures may appear as a flag on an Asset QC Report:

 

During your review of the issues in the Fix Notes phase, please examine the section or sections flagged and give your best determination of whether you can fix the flashes or if they necessary to preserve the creative intent.

 

Common Location for Errors:

Animated Content, Visual effects, Special Effects, and fast edits are the most common locations that a harmful photosensitive pattern may be introduced. Elements of patterns are being manufactured for an intended appearance that does not typically happen in a natural manner. However, this does not suggest these elements do not occur naturally, elements such as the frequency in which light passes behind an object and re-emerge in a physical space can produce a harmful pattern. An example of how this could happen is a shot of the sun 

through a line of trees from a moving vehicle. The trees passing by due the car’s movement could trigger luminance changes that are potentially harmful flashes. 

 

Potential Courses of Action after a Failed PSE Test

After your content has been deemed to contain potentially harmful flashes, there are several courses of action a Post team can take.

 

  • Adjust the luminance of the flashes in the sequence that is affected. 
      1. In DI, use a power window to reduce the luminance of the sections of the screen that contain flashes. All changes in luminance in the flash should be below 20 nits of luminance change.
      2. A global luminance drop could be applied to the entire image, however, in many instances, this will affect the creative intent of the scene.

 

  • Adjust the rate at which flashes or rapid pattern changes occur 
      1. If possible, space out the failed sequences to occur at a rate of less than 3 times per second.

 

  • Take no action 
    1. Please confirm that a change to the content would impact creative intent.
    2. Inform your Netflix Post Production contacts that you will not be taking action.
    3. A warning may be added in the Netflix playback UI.

 

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