Display Stream Compression (DSC) is a lossless or near-lossless image compression standard developed by the Video Electronics Standards Association (VESA) for reducing the bandwidth required to transmit high-resolution video and images. DSC compresses video streams in real-time, allowing for higher resolutions, refresh rates, and color depths while minimizing the data load on transmission interfaces such as DisplayPort, HDMI, and embedded display interfaces.
Why Is DSC Needed?
In the ever-evolving landscape of display technology, the pursuit of higher resolutions and better visual quality is relentless. As display capabilities advance, so do the challenges of managing the immense amounts of data required to drive these high-performance screens. This is where DSC steps in. DSC is designed to address the challenges of transmitting ultra-high-definition content without sacrificing quality or performance. As displays grow in resolution and capability, the amount of data they need to transmit increases exponentially. DSC addresses these issues by compressing video streams in real-time, significantly reducing the bandwidth needed while preserving image quality.
DSC Use in End-to-end System
DSC Key Features
- Encoding tools:
- Modified Median-Adaptive Prediction (MMAP)
- Block Prediction (BP)
- Midpoint Prediction (MPP)
- Indexed color history (ICH)
- Entropy coding using delta size unit-variable length coding (DSU-VLC)
- The DSC bitstream and decoding process are designed to facilitate the decoding of 3 pixels/clock in practical hardware decoder implementations. Hardware encoder implementations are possible at 1 pixel/clock.
- DSC uses an intra-frame, line-based coding algorithm, which results in very low latency for encoding and decoding.
DSC encoding algorithm
- Compression can be done to a fractional bpp. The compressed bits per pixel ranges from 6 to 63.9375.
- For validation/compliance certification of DSC compression and decompression engines, cyclic redundancy checks (CRCs) are used to verify the correctness of the bitstream and the reconstructed image.
- DSC supports more color bit depths, including 8, 10, 12, 14, and 16 bpc.
- DSC supports RGB and YCbCr input format, supporting 4:4:4, 4:2:2, and 4:2:0 sampling.
- Maximum decompressor-supported bits/pixel values are as listed in the Maximum Allowed Bit Rate column in the table below
- DP DSC Source device shall program the bit rate within the range of Minimum Allowed Bit Rate column in the table:
Summary
Display Stream Compression (DSC) is a technology used in DisplayPort to enable higher resolutions and refresh rates while maintaining high image quality. It works by compressing the video data transmitted from the source to the display, effectively reducing the bandwidth required. DSC uses a visually lossless algorithm, meaning that the compression is designed to be imperceptible to the human eye, preserving the fidelity of the image. This technology allows for smoother, more detailed visuals at higher resolutions, such as 4K or 8K, without requiring a significant increase in data bandwidth.
More Information
- Cadence has a very mature Verification IP solution. Verification over many different configurations can be used with DisplayPort 2.1 and DisplayPort 1.4 designs, so you can choose the best version for your specific needs.
- The DisplayPort VIP provides a full-stack solution for Sink and Source devices with a comprehensive coverage model, protocol checkers, and an extensive test suite.
- More details are available on the DisplayPort Verification IP product page, Simulation VIP pages.
- If you have any queries, feel free to contact us at talk_to_vip_expert@cadence.com