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In both areas, there is increasing demand for higher network bandwidth and DSP performance to support high-resolution, multi-stream audio/imaging/video data transport and processing. Unlike traditional mission-critical automotive electronics, the development cycle and lifecycle of the new electronic devices to support infotainment and ADAS applications are becoming shorter and more diversified. And they’re not without their challenges.
To get a handle on those challenges just before we headed off to SAE Convergence at Detroit, I spent some time with Charles Qi, Solutions Director with Cadence.
“Cadence has well-established leadership in audio/imaging/video DSP and audio/video interface IP cores,” he said. “By tapping into this IP portfolio, systems designers can build optimized AV systems targeting automotive applications.”
The figure below illustrates a simplified but representative end-to-end AV reference system constructed largely using Cadence® IP cores.
The system consists of an infotainment head unit, a few image/video endpoints, and audio endpoints connected via automotive Ethernet. In the case of an automotive infotainment application, the reference system forms an end-to-end content processing and distribution platform for in-car music/movie playback, according to Qi. The audio endpoints can be the audio amplifier/speaker systems mounted in different locations of the car. The audio/video endpoints can be the rear-seat entertainment receivers. In the case of an automotive ADAS application, the video endpoint can be attached to camera modules to collect images continuously for panoramic viewing.
Qi explained that the reference endpoint system for audio playback can be constructed with the following Cadence IP blocks:
Audio streams can be transferred from the infotainment head unit to multiple audio endpoints over automotive Ethernet using IEEE 1722 AVTP protocol. Because audio streams are sensitive to jitter and latency, two distinctive features of automotive Ethernet are being utilized to improve audio playback quality. The audio stream distribution is bandwidth- and latency-guaranteed using separate hardware transmit/receive queues and IEEE 802.1Qat stream reservation and IEEE 802.1Qav audio/video bridging protocols. The latency distortion between multiple audio channels or audio and video streams due to different transport delay is corrected via IEEE 1588 time synchronization protocol.
“Over the years, Cadence and our audio partners have built a library of over 125 audio software packages to provide the best in-cabin listening experience using any of the HiFi Audio DSPs. The DSP can also be used to isolate vehicles from engine and road noise in endpoint post processing.\=Additionally, a complex audio playback system requires an AVB software stack to manage the automotive Ethernet. The Tensilica processor has the flexibility to be utilized as a generic CPU running an operating system, the AVB stack, and the application.”
Such an end-to-end audio playback reference system was recently demoed at the IEEE-SA Ethernet & IP @ Automotive Technology Day event in Detroit.
An ADAS application typically requires multiple cameras to be mounted around the body of the automobile to capture live image/video streams continuously. The image/video processing tasks are fairly complex, with different emphasis and intelligence levels including:
Qi said that using the Tensilica IVP image/video DSP processor, the processing tasks can be distributed between video endpoints and the head unit. In the example reference system, the IVP DSP embedded in the video endpoints can perform pre-processing tasks such as stabilization and dynamic range enhancement on raw images captured by individual cameras. Multiple IVP processors can also be deployed in the head unit to support view stitching and object recognition.
“The multi-stream video transport imposes significantly higher demand on network bandwidth, which can only be met using newer networking technology such as automotive Ethernet,” he said. “The time synchronization feature of the automotive Ethernet technology also plays a significant role to ensure the synchronization of multiple video streams from panoramic view stitching.”
Additionally, Cadence MIPI camera and display interface controller/PHY IP cores are being utilized to interface the CMOS camera modules on the video endpoint side and LCD display panel on the head unit side. A complete ADAS reference system can be built exclusively with Cadence IP cores, spanning video capture to video processing to video display.
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