This article provides an overview of how to use AWS Elemental MediaConvert for Dolby Vision and Dolby Atmos encoding. As there are lots of support materials relating to AWS Elemental MediaConvert on the AWS site, so this article focuses on the key steps and settings related to Dolby Vision and Dolby Atmos.

About AWS Elemental MediaConvert

AWS Elemental MediaConvert is a file-based content transcoding service with a web services interface and pay-as-you-go pricing. With AWS Elemental MediaConvert's high-quality video transcoding, you can create on-demand video assets for playback on virtually any device.

MediaConvert can be used to generate media assets that fall broadly into two categories:

• ABR streaming packages: You can create adaptive bitrate (ABR) packages so that the end viewer's device can adapt to changes in the available bandwidth by downloading higher or lower-quality segments. ABR packages are also called ABR stacks, because they are made up of a stack of video, audio, and captions components. Each component in the stack or package is called a rendition.
• Standalone files: You can create standalone files and host them in a location where end viewers download the entire file all at once and then view it. You might also create standalone files and then send them to downstream systems for packaging and distribution.

Getting Started with Dolby Vision Encoding

Dolby Vision source file includes Dolby Vision metadata which is received either as a separate file or as encapsulated within the mezzanine. However, AWS Elemental MediaConvert can encode Dolby Vision outputs from both Dolby Vision and non-Dolby Vision source files. 

If a native Dolby Vision mezzanine with metadata is provided, then you can simply encode it.

If Dolby Vision mezzanine is not provided, you can still encode Dolby Vision by using SDR or HDR sources. This is achieved by an additional process which runs an automated analysis of each video frame of the content and generates Dolby Vision metadata on-the-fly. This Dolby Vision metadata generation process is triggered automatically by AWS MediaConvert when you configure your encoding job with standard HDR or SDR source as input and Dolby Vision as output.

Note: If you have received a mezzanine that contains Dolby Vision metadata then it is likely that the metadata has been carefully crafted by a colorist as part of the content creation process. If Dolby Vision metadata is generated as part of the encoding process within AWS MediaConvert, this metadata will be created based on an automated analysis and does not include artistic intent of the colorist.

Supported Dolby Vision Mezzanine types (Native Dolby Vision Content):

• Apple ProRes QuickTime MOV, with a Dolby Vision metadata XML file.
• MXF file, with a Dolby Vision metadata XML file.
• MXF file, with frame-interleaved Dolby Vision metadata
• IMF package (IMP) with frame-interleaved Dolby Vision metadata or an XML file.

Supported Non-Dolby Vision Mezzanines (Automated Dolby Vision metadata generation):

• Any HDR Mezzanine
• Any SDR Mezzanine

Getting Started with Dolby Atmos Encoding

AWS Elemental MediaConvert can create Dolby Digital Plus with Atmos output by either encoding one of the below source formats, or by passing through already encoded Dolby Digital Plus with Atmos source content.

Supported Dolby Atmos Source Formats:

• Dolby Atmos Master File (DAMF): DAMF is an format that is used by Dolby content creation tools used in studios and post-production suites. DAMF consists 3 files with the extensions, .atmos, .atmos.metadata, and .atmos.audio.

• Audio Definition Model Broadcast WAV Format (ADM BWF): This is a single file that is basically a broadcast WAV with data chunk at the head containing the .atmos and .atmos.metadata information.

• Immersive Audio Bitstream (IAB/IMF): IAB/IMF is an .mxf file with interleaved PCM and metadata. It is a frame based representation of the DAMF in a single file, which is specified for IMF (Interoperability Mastering Format). IMF mastering tools can be import and export IAB/MXF and master to IMF. 

• Channel-Based Immersive (CBI): Dolby Atmos is delivered as CBI (Channel-Based Immersive) or OBI (Object Based Immersive). CBI is primarily used for live events and real-time mixing, while OBI is used for post-produced content. AWS MediaConvert supports channel-based immersive (CBI) content delivered as interleaved WAV file in 9.1.6, 7.1.4 or 5.1.4 channel configurations.

Configure Dolby Vision video encoding

Once you have one of the supported source video files, you can follow the below steps to create a Dolby Vision encoding job.

Step1 – Create a new encoding job in MediaConvert

• Open the MediaConvert console at https://console.aws.amazon.com/mediaconvert
• Click to Create Job to start creating a new encoding job

Step2A – Specify Dolby Vision Mezzanine (encoding native Dolby Vision source)

• Follow this step when you have one of the native Dolby Vision mezzanine types, which are given in previous section. If you don't have a Dolby Vision mezzanine and want to use SDR or HDR source for encoding into Dolby Vision output, then skip this step and proceed with Step2B.
• On the Create job page, in the Job pane on the left, choose Input 1, in the Input file URL box provide the URI to your Dolby Vision Mezzanine file that is stored in Amazon S3 or on an HTTP(S) server. 
• If your source mezzanine includes Dolby Vision metadata as sidecar XML, then you also need to provide the URI to your metadata XML file in the Dolby Vision Studio Metadata XML field.

Step2B – Specify SDR/HDR Source (encoding SDR/HDR source into Dolby Vision output)

• Follow this step when you want to use SDR or HDR source for encoding into Dolby Vision output. Using a non-Dolby Vision source will trigger the automated process which will generate Dolby Vision metadata on-the-fly.

• On the Create job page, in the Job pane on the left, choose Input 1, in the Input file URL box provide the URI to your SDR or HDR source file that is stored in Amazon S3 or on an HTTP(S) server. 

• Important: AWS MediaConvert needs the color space metadata of the source file for conversion between SDR and HDR. If your source video file does not have color space metadata, then you must specify color space in the Color Correction / Color Space field for the input file. Most SDR files do not have color space metadata, therefore you have to populate it manually.

Specify Input file URL:

Specify Dolby Vision Studio Metadata XML (if any):

Configure Dolby Atmos audio encoding

Once you have one of the supported Dolby Atmos source files ready, you can follow the steps below to create a Dolby Atmos encoding job.

Step1 – Specify Dolby Atmos Source File

• On the Create job page, go to the Audio Selectors box and toggle External File button to provide the URL of your audio source file that is stored in Amazon S3 or on an HTTP(S) server. 

Configure Output Groups

After configuring audio and video settings, you will need to configure output groups as described in below steps. 

• In the Job pane, in the Output groups section, choose Add.
• Choose an output group type, and then choose Select. You can choose to output as ABR streaming packages (Apple HLS, DASH ISO, Microsoft Smooth Streaming, CMAF) or Standalone Files (File Group).
• For standalone file output, create one file output group for all the files you intend to create. For ABR streaming package output, create one ABR streaming output group for each ABR package that you intend to create.
• For Destination, specify the URI for the Amazon S3 location where the transcoding service will store your output files. You can specify the URI directly or choose Browse to select from your Amazon S3 buckets.
• Scroll down to the Outputs in the Output Groups, click to the Add output button to create as many video and audio outputs as necessary.

Create Output Group of type CMAF:

Configure Video Encoding Settings

After you added the outputs, you need to specify video encoding settings such as Codec type, bitrate, resolution, frame rate, etc for each output.

• Click to Video output and then specify video encoding settings as necessary.
• To enable Dolby Vision encoding, first you have to set Video codec to HEVC (H.265), Profile to Main10/Main or Main10/High, Color metadata to Insert, and Respond to AFD to None. Once these settings are chosen, Dolby Vision preprocessor button will be activated.
• Toggle the Dolby Vision button in the preprocessors section. Specify Dolby Vision profile and Level6 metadata handling mode. The default Level6 handling mode is Passthrough which takes Level6 from source metadata XML. You can also choose to recalculate Level6 or specify custom values.

Encoding Settings for Dolby Vision Video:

Encoding Settings for Dolby Vision Video (continued):

Turn on Dolby Vision Processing:

 

Configure Audio Encoding Settings

After you added the outputs, you need to specify encoding settings such as Codec type, bitrate for each audio output.

• Click to an audio output and then specify audio encoding settings as necessary.
• Choose Dolby Digital Plus JOC (Atmos) as audio codec, and specify other encoding settings as necessary.

Dolby Digital Plus JOC (Atmos) settings:

 

Start Encoding Job

After you configured all video and audio outputs, your encoding job is ready for execution.

• Click Create button at the bottom of the page and start the encoding job. 
• Once the job is started you can view its status in the AWS console. You can also download your encoding settings as a JSON file.
• When the encoding job finishes, your output files will be ready in the destination. You can use the files for delivery and playback. 

Create the Encoding Job:

 

Tracking the Encoding Jobs