The current mainstream wireless projection technologies include Miracast, Apple’s AirPlay screen mirroring, WIF Alliance’s DLNA (organization has been disbanded), and although there are some other wireless projection protocols, we still follow the mainstream. Airplay screen mirroring has always been the multi screen interaction of Apple’s own devices, and I won’t comment on it. Let’s mainly comment on the advantages and disadvantages of Miracast wireless projection technology based on Android open-source.
Introduction to Miracast
Miracast is a Wi Fi CERTIFIEDMiracast announced by the Wi Fi Alliance on September 19,2012? Certification project. This protocol is built on the foundation of other Wi Fi alliance technologies, including 802.11n protocol,802.11ac protocol, point-to-point connection technology Wi Fi Direct, TDLS, WPA2 encryption in terms of security, WMM (Wi Fi Multimedia) technology that provides quality of service (QoS) and traffic management, WMMPowerSave technology that saves power related mechanisms, and WPS (Wi Fi Protected Setup) technology that facilitates user configuration of the network. Miracast technology specifies the use of ITU-TH.264 video encoding algorithm for compression on videos.
In the Miracast protocol, there are two types of connecting devices, one is the transmitter, also known as the Source. The other type is the receiving end (Sink). The receiving end is further divided into the primary receiving end (PrimarySink) and the secondary receiving end (SecondarySink), with the difference being that the main receiving end supports image or sound output; The secondary receiver only supports sound output.
The advantages of Miacast are as follows:
Miracast is integrated with the Android system, so all Android phones do not require additional development and can be used. That is to say, on the mobile end, there is no need to install any additional apps, and it can be mirrored for screen projection.
The main drawbacks of Miracast are as follows:
When Miracast is working normally, Wi Fi operates in P2P mode, and the source and receiver establish a one-on-one connection. That is, when a device establishes a connection with a receiving end, other devices cannot see the receiving end, and therefore cannot project the screen. Only after the device exits the connection can other devices project screens. So the preemption function cannot be implemented.
Miracast encapsulates the UDP transport protocol at the bottom layer, without a rigorous Q&A mechanism. So in actual use, when encountering interference, it is easy to cause frame loss and screen blurring. During the transmission process, once there is a splash screen, it gives customers a very bad feeling. The reason why wireless screen projection devices on the market often have splash screens and mosaics is this.
In addition, Miracast is provided by an operating system supplier and is generally used on Android systems. However, the Android protocol causes the phone to have no sound when casting the screen, which is quite frustrating. Most users have to turn on Bluetooth when casting the screen wirelessly on Android phones, in order to facilitate the sound casting process.
Miracast wireless projection technology currently has the most users, but the quality is not high. This is mainly because Miracast is open source for the Android system and many companies use it without conducting secondary research and development, resulting in a proliferation of wireless projection devices on the market, including boxes.