In the relatively new, ever-changing arena of High Dynamic Range (HDR) technologies, there are quite a few options to consider when it comes to creating video content with rich, beautiful, pronounced pictures with both brighter and darker colors. These include HDR10, HDR10+, HLG, HLG10, and Dolby Vision. This post focuses on the key benefits of Dolby Vision, and how to configure a Dolby Vision enabled stream using AWS Elemental Live encoders.

What is Dolby Vision?

Dolby Vision is an HDR technology built by Dolby Laboratories, Inc. Its key differentiator versus other HDR formats is the use of dynamic metadata. This metadata, present in every video frame, allows video displays that support Dolby Vision to map the video to the capabilities of the panel itself. This delivers an optimal result in terms of color accuracy, along with more accurate bright and dark area rendering on-screen. HDR10, for example, uses a static metadata implementation, which limits the contrast and color accuracy a viewer experiences compared to watching in Dolby Vision. Using a 10-bit color depth on AWS Elemental Live with Dolby Vision unlocks a possible 10 billion colors vs. the Rec 709 8-bit that uses only 16.7 million possible colors.

 

Singer: Dolby Vision vs SDR

Bird: Dolby Vision vs SDR

Why Dolby Vision?

Dolby Vision is being adopted by both content creators and producers alike. For example, Apple, one of the globe’s largest manufacturers of computers, tablets, and mobile phones announced in 2020 that their flagship models iPhone 12 and 12 Pro/Pro Max would be able to record and play content in Dolby Vision natively. In the world of over-the-top (OTT) streaming, especially for video on demand (VOD) services, quality is often one of the key benchmarks of a service. Viewers are growing accustomed to seeing HDR-enabled content on their screens – whether they are recording movies on their phones of their loved ones, or streaming this month’s binge-worthy new series.  Prime Video and Netflix, two of the industry leaders in video streaming, currently support HDR10 and Dolby Vision. Quality matters both for content producers looking to gain a differentiating edge, and consumers who have grown accustomed to outstanding video and audio experiences.

Through a software license on your AWS Elemental Live encoder, deploying this technology is simple. The functionality raises the bar of the viewership experience and removes the need to purchase extra hardware for Dolby Vision processing.

Configuring an event with Dolby Vision on AWS Elemental Live

AWS Elemental Live is a robust, feature-rich, on-premises appliance that performs advanced encoding, transcoding, and other stream conditioning functions, including Dolby Vision stream processing. At a high level, a Dolby Vision stream is composed of a base layer (BL), potentially an enhancement layer (EL), and reference processing unit (RPU) sub-streams, depending on whether single or dual PID transmission is being used.  For the purpose of this post, we focus on RPU as it is a part of HEVC header where Vision dynamic metadata is stored. AWS Elemental Live takes in any HDR input type and inserts RPUs to generate a Dolby Vision compatible output.

AWS Elemental Live supports Dolby Vision color space conversion for Profile 5 and Profile 8.1. Dolby Vision profiles consider a number of requirements that define the video characteristics and the playback capabilities.  Profile 5 is a single layer with Dolby Vision-only support and profile 8.1 is a single layer with HDR10 + Dolby Vision compatibility. The following tables provide an overview of both profiles’ characteristics.

 

Table 1: Dolby Vision bitstream profiles

Table 1: Dolby Vision bitstream profiles

 

Table 2: BL signal cross-compatibility ID

Table 2: BL signal cross-compatibility ID

 

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Table 3: Dolby Vision levels

For more information about Dolby Vision profiles, see Dolby Vision Profiles Specification.

The following configuration guide covers general prerequisites, requirements, and step-by-step instructions to set up an event with Dolby Vision enabled.  It also demonstrates how to verify that Dolby Vision stream conditioning is taking place through the messages.

Prerequisites:

  • AWS Elemental Live version 2.21.1 GA or later
  • HEVC license
  • Dolby Vision license

 System hardware requirements:

  • 1080p outputs: Any L800 series appliance
  • 4K HEVC outputs: L840s, L880, or L730 systems

Input requirements:

  • Minimum input: 1080p
  • HDR input
  • Dolby Vision is supported in all inputs type.

Output requirements:

  • Codec: Must be HEVC
  • Profile: Only supports Main10/Main and Main10/High profiles.
  • Enable the color corrector pre-processor
  • Video range:
    • Select Passthrough if the input source uses already full range of bits.
    • If the input video is not full range, select Full Swingto effectively convert up to Full Range. IMPORTANT: If input is already in full range, do not select Full Swing to avoid unnecessary up-conversion.
    • Color space conversion: Select Profile 5 or Profile 8.1 option, as applicable. Profile 5 is a single layer with Dolby Vision-only support and profile 8.1 is a single layer with HDR10 + Dolby Vision compatibility.

Step 1: Create the event

  1. In the AWS Elemental Live web GUI, select New Event.
  2. For your input, specify an event nameand select the type of  The AWS Elemental Live software supports the ingest of HDR content in resolutions from 1080p(FHD) up to 4K(UHD). For this example, HDR content is carried by HD-SDI or Quadrant 4k.
  3. Select Advanced, go to Video Selectorand under Color Space select Follow. If your source is HDR, the encoder is able to insert RPUs to generate a Dolby Vision compatible output.

 

Elemental Encoder: Create an Event; Input

 

  1. In the output side, configure your video elementary stream for Dolby Vision.
  • Codec: Must be HEVC(H265)
  • Insert Color Metadata: Enable

 

Elemental Encoder: Create an Event; output

 

  • Profile: Elemental only supports Main10/Main and Main10/High profiles
  • Under Advance > Preprocessors enable Color Corrector.
  • Video Range:
    • In this example the Input is already full range, for this case select Passthrough
    • If the input is video range, select Full Swingto effectively convert up to full range. IMPORTANT: If input is already in full range, do not select Full Swing to avoid up-conversion again
    • Color Space Conversion: Select Profile 5 or Profile 8.1

 

Elemental Encoder: Create an Event; Dolby Vision Settings

 

Checking for Dolby Vision processing

In the Elemental encoder, once the channel has started, go into the event dashboard and scroll-down to the “Output Group Control”. There you can check in the Statistics section for the Dolby Vision profile that is running. In the following example, the output video has been processed with Dolby Vision profile 5. If Dolby Vision processing is not running the statistics prompt N/A.

 

August24 20219

 

Playing back your content in a Dolby Vision capable device

Dolby Vision is supported in the latest media devices like TVs, setup-boxes, phones, and PCs. The following example was encoded by the AWS Elemental Live encoder and shows a comparison of Dolby Vision vs SDR content played by an iPhone 12.

 

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Conclusion

Dolby Vision is a compelling HDR technology. Using the preceding steps to configure your AWS Elemental Live encoder you are on your way to building a truly beautiful, high quality workflow.  Setting up your AWS Elemental Live encoder takes only a few simple steps: satisfy the prerequisite requirements on the encoder, create your event, and validate Dolby Vision encode is taking place through a quick log check.  We encourage you to explore the incredibly rich, vibrant video streams you can create using the method above. To learn more visit: https://aws.amazon.com/elemental-live/.

Categories: Media