Different Options for Distributing 8K to End User
8K Single-Layer Distribution
Once 8K content has been produced, it can be transmitted using either broadcast or streaming mechanism. 8K can be distributed as a single layer using high capacity networks via satellite, fiber or fiber/coax hybrid cable network solutions (with DOCSIS 3.1/4.0).
The most notable example is the NHK satellite deployment in Japan that started in December 2018.
8K Dual-Layer Distribution
A dual-layer approach may be well suited for bandwidth-limited networks such as Over the Air (OTA).
8K distributed as dual 4K-8K layers can be based on:
- Scalable HEVC (SHVC) or VVC scheme
- MPEG-5 LCEVC standard, making use of a 4K HEVC or VVC base layer. Some believe that LCEVC is a more efficient solution than traditional scalability approaches. LCEVC reduces encoding complexity by a factor of 2.5x to up to 4x when compared with a native codec used at full resolution, with the higher reduction achieved when enhancing newer generation base codecs
We expect such solutions to mature during the 2021–2022 time frame, meaning a commercial deployment after 2024.
4K Distribution for 8K Consumption
This approach takes the 4K signal generated from the 8K source and distributes over a 4K capable network either broadcast or OTT. The 4K signal can be produced in the early stage of the workflow before the mezzanine compression or just before the final compression.
The 8K mastered content is down-sampled to 4K in order to reduce the transmitted bandwidth and have the receiver up sample the delivered signal to 8K. This can be done using multiple techniques such as the AI-based downconversion/upconversion scheme implemented by Samsung called Scalenet (see presentation). MediaTek is also using a paired AI SuperResolution approach to offer a similar capability.
Note that both MPEG and MPAI are investigating AI-based downconversion/compression/decompression/upconversion schemes. This is a long-term approach that will take several years to emerge.
Once the content is decoded, it will be reconstructed to 8K by either the receiver or the TV.
Dynamic Resolution Distribution
This approach transmits only the resolution required by the content which will vary between 4K and 8K dynamically. Analysis of the content complexity can be made on short duration segments, typically two seconds.
The benefit of this approach is the consumed bandwidth in the network will be somewhere between 4K and 8K bandwidth while the end user will receive 8K bandwidth for scenes where the extras resolution makes a difference.
Such an approach is already well supported by Adjustable Bit Rate (ABR) players, as Netflix uses already similar technique for VOD. It is also supported in IP-based broadcast receivers such as ATSC 3.0 and can also be deployed in more traditional Broadcast TS schemes using independently encoded segments. This will of course have to be proven by interop testing campaigns.