Industry Expert Blogs

There will be many cameras in our future cars. Rear view, surround view, mirror replacement, driver monitoring and front view ADAS applications all require one or more cameras. The wiring to hook up all these cameras to the electronic systems that are positioned elsewhere in the car can become quite complex. Replacing traditional wiring in our cars with the new 100BASE-T1 Ethernet standard has many advantages. This communication standard uses unshielded twisted pair cables to deliver data at a rate of 100Mbps. Due to the simpler wiring, smaller connectors, and a switched network, cost is reduced by 80 percent and weight by up to 30 percent compared to LVDS-based systems. We wrote an article on automotive Ethernet before, debunking the myths that it won’t work for ADAS applications. This time we’ll discuss the H.264-based video coding for automotive Ethernet in more detail.

Transmitting even a low-resolution 1.3Mpixel, 4:2:0, 8-bit, 30fps video stream consumes about 500Mbps of bandwidth. In order to ship this data over the 100Mbps 100BASE-T1 link, you need to compress the video. The most commonly used standard for video compression today is H.264. It has been around for over a decade. The first version was approved in 2003, and many SOCs support encoding or decoding H.264-coded bitstreams. Our phones, our PCs, our TVs, they all support H.264 for video capture or playback. No wonder the H.264 standard became the standard choice for automotive Ethernet also. So if your automotive camera supports H.264 and your head unit or ECU supports H.264 then you’re all set right? Unfortunately, things are not that simple. There are many variants of H.264, and different ways to implement an H.264 codec. Simply “supporting H.264” isn’t enough. Below you’ll find an overview of the many variants of H.264 and how especially the requirements for an H.264 codec for consumer and automotive applications are very different.

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