Company in May 2015 to do a hardware class products, using SOC (CPU+DSP) chip solution to do a high-definition conference room terminal, in addition to meeting functions, need to have multi-channel wireless screen function. Project from May, after building a team, research and development, production, testing, to January 2016 to complete a period of functional and trial production, during a lot of difficulties and twists and turns, is divided into a series to do the next review, this article about Miracast HDCP.
about the basic knowledge of miracast, we can Baidu self-search, as a primer to learn. If you enter the development phase, you need to learn three white papers:wi-fi_display_specification_v1.1, wifi_p2p_technical_specification_v1.2 and HDCP Interface Independent Adaptation Specification Rev2_2_final. Our product requirements are to support multi-channel miracast sink functionality on SOC chips (Linux). The whole miracast process includes the establishment of wireless link, call establishment, media acceptance, decoding, rendering and so on. This scope only includes the Wireless Link establishment and call establishment process.
HDCP full name high-bandwidth Digital content Protection (HDCP), mainly for the protection of high-definition video content copyright protection, widely used Bluetooth CD-ROM, video card, display and so on. HDCP standard for video content transmission media have different specifications, covering Hdmi/dvi/hdbaset, DisplayPort, HDBaseT, MHL, USB, DiiVA, WHDI, WirelessHD, DLI, GMSL, Gvif, And the Miracast/widi we're going to design. Since the hdcp1.x specification has been cracked, the current HDCP specification has reached 2.2. of which miracast use is 2.+. Refer to http://www.digital-cp.com/sites/default/files/specifications/HDCP%20Interface%20Independent%20Adaptation% 20specification%20rev2_2_final.pdfto develop and test HDCP, you need to purchase the HDCP Association key. To buy a key, you must become a member to buy key (5k American Knife/10k), members need to pay annual fee (1.5w American knife). The membership and purchase process is not complicated, but it takes some time to understand. due to key leakage failure time delay, there are many small domestic manufacturers are not to buy genuine key, and to go through various channels from other manufacturers to purchase or borrow key, and even a lot of market-oriented dongle and set-top boxes, are using the same key.
The development process is not complicated, the main content is 3 blocks: miracast process modification, hdcp2.x signaling implementation, hdcp2.x encryption media decryption, hardware acceleration algorithm use. The whole process invested 2 people for 2 months, a total of 4 people months of work. since the purchase cycle of key at that time also needs about 1 months, the impact of debugging, so we also borrowed from other manufacturers to use a key for debugging. The development process is very hard, but need to do two points: believe will be able to tune out, familiar with HDCP 2.X specification.
MIRACAST/HDCP of wireless HD Conference room Terminal
