The Video Electronics Standards Association (VESA) today announced it has released version 1.2 of the Display Stream Compression (DSC) Standard. An extension to the feature set offered in version 1.1, DSC v1.2 was developed to support a wider range of display applications — in particular, externally connected displays such as PC monitors and televisions. A key feature of DSC v1.2 is its ability to provide native compression of the YCbCr 4:2:0 and 4:2:2 video formats commonly used in digital TVs.
Developed as an industry-wide compression standard for video interfaces that features low latency and visually lossless performance, DSC is currently integrated into standards used for embedded display interfaces within mobile systems. These include the VESA embedded DisplayPort (eDP) Standard v1.4b and the MIPI Display Serial Interface (DSI) specification v1.2 and later versions. Since its initial introduction in April 2014, the DSC standard has achieved broad adoption in smart phones and tablets, and will be used in future notebook PCs. Examples of mobile processors that currently make use of DSC 1.1 include the NVIDIA Tegra X1 and the Qualcomm Snapdragon 820.
The forthcoming VESA DisplayPort (DP) 1.4 specification will be the first DP standard to take advantage of DSC 1.2, which is backward compatible with DSC 1.1. A side-by-side comparison of the two versions can be found here.
The new capabilities in DSC 1.2 will allow the standard to be utilized not only for mobile displays, but also for emerging high-definition TVs. Key features include:
- Native 4:2:0 and 4:2:2 coding — Eliminates the need to convert pixels into red, green, blue (RGB) components, which allows for direct compression of incoming sub-sampled pixels. This enables more efficient compression (e.g., 2:1 for YCbCr 4:2:0 coding versus 3:1 with RGB conversion), which in turn results in superior image quality for digital TVs, which often utilize YCbCr 4:2:0 coding.
- Up to 16 bits per color — Expands the number of bits per color that can be used, supporting native pixel coding at 8, 10, 12, 14 and 16 bits per color for input and output formats. DSC 1.1 supported only 8, 10 and 12 bits per color. The additional support of 14 and 16 bit depth allows complete compatibility with existing transports and wide color depth pixel formats — enabling the display of very high color depth content.
- High Dynamic Range (HDR) — HDR TV shows and movies are becoming available for on-line streaming, and Ultra HD Blu-ray discs with HDR titles are expected to hit the market soon. Because the higher color depth of HDR requires more data, the increased compression efficiency of 4:2:0 format by DSC 1.2 and through the soon-to-be-launched DP 1.4 transport specification (which recognizes the BT.2020 color standard) will be a key enabler for driving adoption of HDR TV technology — especially as resolutions increase beyond 4K.