Recommended Systems for 8K Playback. Part 2: Using 12G SDI
By Mauricio Alvarez-Mesa, PhD — Spin Player is a software media player based on highly optimized HEVC and VVC decoders and an advanced video rendering engine. The media player allows the playback of high-end 8K video using standard PC systems.
An important component of the video playback chain is the output interface. Spin Digital currently supports video rendering with GPUs that include up to 4 DisplayPort outputs which can be combined to form a single 8K frame, or GPUs with one HDMI 2.1 output. The use of the HDMI 2.1 interface facilitates the transmission of the 8K signal to the display as a single cable is needed. More information about 8K playback with GPUs rendering can be found in a previous edition of our tech blog.
With GPU video rendering, however, it is not always possible to have a full control of the video output as the device can perform automatic color conversions. In addition, the video output format depends on the capabilities of the OS desktop compositor, for example in Windows 10/11 only HDR10 (PQ) is supported.
To address some of the limitations of GPU rendering Spin Player offers CPU-based rendering with SDI output as an alternative.
The SDI support is addressed for professionals requiring maximum control of the video processing and display chain.
In this tech blog we describe the use cases, requirements, and systems needed for 8K playback using SDI interfaces
12G SDI for 8Kp60, 8Kp120, and Beyond
12G SDI offers the bandwidth required for the transmission of uncompressed 8K (7680x4320px) video at 60 Hz with 4:2:2 10-bit format, by using a quad-link 12G configuration as specified in the SMPTE ST 2082-12 standard.
For 8Kp60 the 12G interface requires a single SDI board and only 4 12G SDI cables as opposed to two devices and 16 cables as with 3G SDI.
12G SDI can also be used for 8Kp120 playback for High Frame Rates (HFR) or 8K 3D (stereoscopic) applications by using two 12G SDI boards. Spin Player supports this feature called multi-device, which allows combining several output devices to create a single output. This feature supports different operation modes including: clone (same output in all devices), tiled (single large surface divided across multiple devices), and alternate (interleaved output among devices).
Spin Player with SDI output can be used for professional 8K HDR playback, without the limitations of GPU-based rendering. That includes: no hidden conversions during the rendering process and support for HDR10 (PQ) and HLG HDR formats. Other HDR formats such as HDR10+ and Dolby Vision could be supported as well (but are not yet available in Spin Player).
By using multiple 12G SDI cards it is also possible to support resolutions beyond 8K including 16Kp60 for very-large scale visualization systems.
System Configuration for 8K Playback with 12G SDI
Spin Player supports various SDI devices from multiple manufacturers including: AJA 12G Kona 5, AJA Corvid 44 12G, and Blackmagic DeckLink 8K Pro.
Spin Digital is working closely with SDI device manufacturers to ensure maximum performance and quality for 8K playback.
See more information here:
When using SDI as the output interface, the video rendering process (color conversion, pixel format conversion, chroma subsampling, etc) is performed on the CPU. Spin Digital has developed an optimized library of video processing filters called SpinFilter for CPU video processing and rendering. Spin Player selects and configures automatically this optimized CPU rendering library.
8K playback with SDI requires more CPU resources than GPU-based rendering as the rendering and post-processing is performed by the CPU. Spin Player highly optimized CPU processing filters reduce the extra resources needed.
Display Systems for 8Kp60
Spin Player with 12G SDI output can be used for 8K playback on different types of 8K displays. Currently there are no professional 8K TVs with SDI input. Therefore the SDI signal has to be converted to a consumer format such as HDMI or DisplayPort. Only some high-end 8K projectors accept the 12G SDI signal directly.
8K TV with HDMI 2.1 Input
For connecting the 12G SDI output of the media player to an HDMI 2.1 8K a converter from 4x 12G SDI to HDMI 2.1 is needed.
Currently the only solution available for that purpose is the professional SD-7076 converter from Astrodesign.
8K TV with HDMI 2.0 Input
Some 8K TV models accept 4x HDMI 2.0 inputs. A player with SDI interface can be used in combination with 4x 12G SDI to HDMI 2.0 converters that can be acquired commercially from different vendors including AJA or Black Magic.
8K Projector with SDI Input
Some projectors support 8K resolution and directly accept 12G-SDI as input interface. Spin Digital presented in May 2019 a demonstration of 8K playback at the Festival de Cannes using Spin Player with 12G SDI and the Insight laser 8K projector from Digital Projection.
Display Systems for 8Kp120
Spin Player with 12G SDI output can be used for 8K HFR or 3D (stereo) playback on devices that accept 8Kp120 SDI input. The recommended format is called alternate rendering, in which 8Kp120 is presented as 2x 8Kp60 outputs using 2 SDI devices each one taking care of the odd and even frames.
Spin Player with 12G SDI output can be used for professional 8K video playback. It performs high-precession video rendering on the CPU without hidden conversions, supports multiple HDR formats (HDR10 and HLG), and by combining multiple devices it can be used for 8K 120 fps or even 16K 60 fps playback.
Note and Disclaimer
These recommendations are based on internal tests performed by Spin Digital. This information is provided “as is” and it does not imply any warranty or assurance. If you have more specific requirements, please contact us.
Spin Digital, Spin Player HEVC, and Spin Player VVC are trademarks of Spin Digital Video Technologies GmbH.
Other trademarks remain the property of their owners, and are used here for descriptive purposes.