Modern Embedded Video

The demand for high-quality video in embedded applications has grown exponentially with advancements in consumer and automotive technologies. From consumer products like security intercoms and portable gaming devices to advanced automotive systems, such as digital mirrors and infotainment, the integration of high-resolution video has become a critical component of embedded systems. These devices must now support a variety of resolutions, frame rates, and color spaces to meet the growing needs of consumers and industry professionals alike.

High-definition (HD) video with resolutions such as 1080p (Full HD) and 4K Ultra HD are now commonplace, with frame rates ranging from 30 to 120 frames per second (fps). Color spaces have also evolved, with ITU-R BT.709 being standard for HD content and ITU-R BT.2020 emerging as the preferred choice for Ultra HD and HDR (High Dynamic Range) content, offering richer and more vibrant colors. Handling these complex formats requires sophisticated video processing and interface ICs (Integrated Circuits), which are critical for ensuring smooth, high-quality video experiences across a wide range of applications.

Embedded video applications in consumer electronics are increasingly diverse. Security intercoms now incorporate high-definition video feeds with a wide dynamic range for enhanced clarity, even in challenging lighting conditions. Portable gaming devices are expected to render video with low latency and high resolution, providing a seamless gaming experience. Meanwhile, automotive applications have introduced video into critical safety systems, such as digital mirrors, cameras, and infotainment displays. These systems rely heavily on interface ICs to manage video transmission efficiently.

Figure 1 – Applications of video processing and interface ICs

Automotive Video Requirements

The automotive industry has emerged as a key driver of advancements in video technology, particularly in driver assistance systems, infotainment, and in-car displays. Automotive video systems must meet stringent requirements for real-time performance, reliability, and robustness, especially given the challenging environmental conditions in which vehicles operate.

Often, a common distinction is made between ICs for video processing and those for video interfacing.  Processing ICs handle tasks such as scaling, compression, and format conversion, ensuring the video is optimized for the intended display or camera system.  The figure below shows a generalized application diagram.

Figure 2 – Video processing requirements within a vehicle

Interface ICs manage the transmission of video signals between different components in the system. They translate signals between various protocols and standards, ensuring operability between devices such as cameras, displays, and control units. In the figure below, numerous standards are depicted to illustrate this functionality.

Figure 3 – Video interface requirements within a vehicle

For example, a backup camera may transmit video using one protocol, while the vehicle’s infotainment display requires a different protocol. An interface IC bridges this gap, converting the video signal into a format compatible with the display, all while maintaining the high resolution and frame rate required for smooth video playback.

In embedded video, several interface standards are commonly used to manage the transmission of video signals. Two of the most prevalent are Low-Voltage Differential Signaling (LVDS) and the standards set forth by the Mobile Industry Processor Interface Alliance (MIPI).

LVDS (Low Voltage Differential Signaling) is a popular interface standard for transmitting high-speed data over copper. It uses low-voltage signals to reduce switching power consumption and electromagnetic interference (EMI), making it ideal for embedded applications where efficiency and reliability are paramount. LVDS is widely used in automotive video systems, where it helps maintain signal integrity over long distances, such as from cameras to in-car displays.  (https://riverdi.com/blog/interfaces-in-lcd-display-modules-spi-i2c-lvds-mipi-vx1-edp-and-others#LVDS_–_Low_Voltage_Differential_Signal_interface)

The MIPI Alliance (https://www.mipi.org/about-us), an industry consortium that develops interface specifications, plays a pivotal role in standardizing video interfaces. Two key MIPI standards are MIPI CSI-2 (Camera Serial Interface) and MIPI DSI (Display Serial Interface). MIPI CSI-2 is designed for high-speed image data transmission from cameras to processors, making it ideal for applications like automotive cameras and security systems. Meanwhile, MIPI DSI is optimized for transmitting video data from processors to displays, ensuring high-quality video playback in devices like infotainment systems. (https://focuslcds.com/journals/the-differences-between-mipi-csi-and-mipi-dsi/)

Another standard gaining traction is Embedded DisplayPort (eDP), which is designed specifically for video transmission between a systems-on-chip (SoC) and a display in embedded applications. eDP offers high bandwidth, low power consumption, and the ability to drive high-resolution displays, making it a preferred choice for automotive and consumer applications requiring high-definition displays.  https://www.vesa.org/wp-content/uploads/2011/01/ICCE-Presentation-on-VESA-DisplayPort.pdf

ROHM’s ML86798 and ML86799 Interface ICs

As video interface requirements become more complex, ROHM has developed solutions designed to meet the challenges of modern embedded video applications. ROHM’s ML86798 and ML86799 interface ICs are cutting-edge devices that facilitate the conversion of video signals between different standards, making them indispensable for applications that require seamless video transmission across various components.  An overview of these two devices is presented in the figure below.

Figure 4 – Interface ICs needed to convert between different standards

The ML86798 is an interface bridge that supports the input of Single LVDS, MIPI-DSI/CSI-2, and the output of MIPI-DSI/CSI-2 or eDP. This flexibility, shown in the block diagram below, allows for various interface conversions between peripheral devices, making it ideal for systems that require interoperability between different video standards. For example, the ML86798 can take video input from an LVDS camera and output it to a MIPI DSI display as part of a rearview backup camera system. The ML86798 can also take video input from a MIPI DSI of one SoC and output MIPI CSI-2 to another SoC for interface conversion between SoCs.

Figure 5 – Block diagram of ROHM ML86798

The ML86799 is an interface bridge that supports both Single and Dual LVDS inputs and outputs MIPI DSI/CSI-2 or eDP. This IC, shown in the figure below, is designed for systems that require high-speed data transmission between devices, such as automotive infotainment systems and digital mirrors. The ML86799 ensures that high-resolution video is transmitted with minimal latency, making it suitable for applications where real-time video is critical.

Figure 6 – Block diagram of ROHM ML86799

Both of these devices are essential for ensuring the smooth transmission of video signals in modern embedded applications. Their ability to handle multiple standards and protocols makes them highly versatile, enabling manufacturers to design reliable and future-proof systems. For example, the ML86799 can take video input from an LVDS of an SoC and output it to an eDP display for interface conversion between SoCs and LCDs.

Conclusions

ROHM has established itself as a leader in the development of video interface ICs, providing solutions that address the growing demands of high-resolution video in embedded systems. The company’s lineup of video products, including the ML86798 and ML86799, supports various interface conversions, making them ideal for applications in automotive, consumer electronics, and beyond. These ICs offer compatibility with larger panels, higher resolutions, and advanced video standards like eDP and MIPI CSI-2, ensuring they can meet the needs of even the most demanding applications.

As video technology continues to evolve, ROHM remains at the forefront, delivering innovative solutions that enable high-definition video transmission with unparalleled reliability.

To learn more, visit:

https://www.rohm.com/products-info/video_video-interface