Nowadays the HDMI interface is widely used from the home theatre systems to the professional studios. It is capable of transmitting 8-channel audio and auxiliary data with the uncompressed video signal. HDMI is developed continously, the latest version supports three dimensional video, ethernet frame forwarding and an audio channel, which is directed backwards to the source of the video. My task is in connection with the input and output cards of an HDMI 1.4 compatible modular matrix, constructed by Lightware Kft. These cards can handle 8 HDMI ports and in addition to implementing the expansions of HDMI 1.4, they should be able to manage HDCP encrypted signals, audio streams and the standardized descriptor information of attached sink devices.
As the first part of the task, I reviewed the basics of the HDMI standard, the expansions of HDMI 1.4 and the HDCP standard of encryption, which was developed to prevent the illegal copying of digital content. After getting acquainted with the requirements and the whole system, I implemented the desired functions by the help of special integrated circuits, which were designed to handle the HDMI stream. An HDMI port processor, manufactured by Silicon Image, plays a central role among these devices, because it is fully compliant with HDCP and supports HDMI 1.4 upgrades, so it is perfectly suitable for the intended purpose. I created the firmware of the microcontroller, which is responsible for the proper opeation, and the developing process was finished with a thorough testing phase.