SNAA333 April   2020 CDCE6214-Q1

 

  1.   eAVB Media Clock Synchronization Using CDCE6214-Q1 Clock Generator
    1.     Trademarks
    2. 1 Introduction
    3. 2 AVB Protocols and Network Structure
    4. 3 AVB End Station Architecture
    5. 4 Talker, Listener, Presentation Time, and Media Clock Synchronization
      1. 4.1 Talker and Presentation Time
      2. 4.2 Listener and Media Clock Synchronization
    6. 5 Reference CDCE6214-Q1 Schematic and Programming Guide
    7. 6 Summary
    8. 7 References

1 Introduction

Modern media systems for automotive infotainment and driver assistance are composed of multiple sensors, cameras, displayes, and content players. Point-to-point interconnections with shielded twisted pair or coaxial cables may not be practical for all of the required components. Ethernet is gaining more traction in the automotive audio visual market segment due to its convenience and fast transmission speed; however, standard asynchronous Ethernet networks do not carry clock synchronization information. One of the main goals of AVB protocols is to achieve time and clock synchronization over Ethernet.

Consider the example below where the live or playback audio and video are presented on two RSE (Rear Seat Entertainment) displays and multiple speakers at the same time. Speakers and RSE displays are connected to the Head Unit through Ethernet. For excellent user experience, media content should be lip synchronized, and both audio and video should be distributed to all speakers and displays synchronously.

01-infotainment-bd.gifFigure 1. Ethernet Time Synchronization in Automotive Infotainment System

Two types of A/V synchronization are required:

  1. The A/V (audio and video) content shall start and stop playing at the same time, which requires a common time reference for multiple events to trigger simultaneously.
  2. The media content should be sampled and reconstructed at the same rate for high-fidelity A/V systems.

See Section 2, Section 3 and Section 4 to understand how to achieve the two types of synchronization and how the CDCE6214-Q1 device fits in media clock recovery.