How to implement wireless video transmission

Jacktang

How to implement wireless video transmission [Copy link]

From a technical perspective, there are currently two ways to display images on a display wirelessly.

　　The first method is to transmit video data. The way it works is that at the video transmitter, the video stream is first compressed and wirelessly sent to the receiver in the form of data packets. After receiving the data packets, the receiver reassembles them and then decompresses them to restore the image. There are many solutions for this method on the market, and the more representative ones are implemented through WIFI technology or UWB technology.

The second method is to directly transmit the video stream without compressing and decompressing the video. The path is intuitive, but the technology is difficult. The most representative technology is WHDI.

　　The wireless video technology using UWB and WIFI compresses the video stream first and then transmits it, and finally decompresses and restores it. This process is time-consuming and is the direct cause of video delay, which is unavoidable.

　　The wireless video technology using WHDI does not require compression and restoration, which saves the time of compression and decompression, and can fundamentally solve the problem of delay. However, since the data bandwidth occupied by the video stream is very high, only WHDI technology can achieve this in the wireless field.

Transmission distance

　　One of the main performance indicators of wireless is the transmission distance. The transmission distance can be divided into visible transmission distance and obstructed transmission distance. The meaning of visible transmission distance is the receiving distance of the receiving end under the premise that the wireless transmission device can be seen within the user's line of sight.

　　Although they are all wireless technologies, each has its own characteristics. UWB technology is a wireless technology with the shortest transmission distance, with a straight-line transmission distance of about 5 meters. It is ineffective if blocked. Wireless UWB displays can only transmit at short distances.

　　WIFI technology can only transmit 2 to 5 meters while ensuring the minimum image delay and the best resolution. Of course, if you don't mind using standard definition resolution (480i) for entertainment and office work with an image delay of up to 1.5 seconds, I believe its transmission distance of about 30 meters will be much better than UWB.

WHDI technology has a transmission distance of about 30 meters, and the image resolution is as high as 1920*1080, that is, 1080P/60, and there is no image delay. This is due to its own uncompressed technical characteristics and advanced MIMO antenna design (4 antennas x 5 antennas).

What is WHDI?

WHDI (Wireless Home Digital Interface) sets a new standard for wireless high-definition video connections. It provides a high-quality, uncompressed wireless connection. The MIMO technology and OFDM modulation adopted by it can achieve a transmission rate of up to 3Gbps. It works in the 4.9GHz~5.875GHz frequency band, 20MHz or 40MHz channels, complies with global 5GHz spectrum regulations, has a range of 30 meters, can penetrate walls, and has a delay of less than 1 millisecond.

WHDI supports new devices, consumers connect their A/V equipment and consume content, the scope can cover the whole home, WHDI allows users to connect any source in the home to any location display. With WHDI, the TV in the living room can show the Blu-ray player in the bedroom, the HD DVD player, the kitchen TV can show the content on the home office PC, and game entertainment can be played on the projector in the basement without moving the game console from the children's bedroom or basement. This new standard of WHDI facilitates the transmission of uncompressed HD video, separate video players, and multiple indoor HD video connections using a revolutionary video modem method to support coverage throughout the home.

WHDI specifies high-definition video transmission, as well as audio and control. The comprehensive WHDI control protocol will enable users to centrally control all A/V devices in the home, with almost no transmission delay, and users will not encounter the problem of sound and video asynchrony. They can also use WHDI to connect to network entertainment audio, video and games.

WHDI Features

Uncompressed video transmission

The most essential difference between WHDI technology and other wireless technologies is that it can transmit full HD audio and video streams without compression. Currently, there are two main ways to transmit video wirelessly: one is to transmit the compressed audio and video streams wirelessly at the transmitter, and decompress and restore the image at the receiver, represented by WIFI and UWB technology. The other is to directly transmit the video stream output by the video source to the receiver wirelessly and output the image, represented by WHDI. Currently, only WHDI technology can achieve this in the industry.

No delay in transmission

Since WHDI technology provides sufficient wireless bandwidth, there is no need to transmit video in a compressed manner, saving the time spent in video compression and decompression, so it can ensure that the transmitted video is completely delay-free.

Resolution up to 1080P

WHDI technology supports video resolutions up to 1920X1080P. Through subsequent software upgrades, it can support resolutions up to 2K X 4K, which is equivalent to 4 times 1080P.

Support 7.1 channels

In addition to being able to transmit full HD video, WHDI technology can support 7.1-channel (PCM) audio transmission with a sampling rate of up to 24-bit, 192KHz.

100K return channel

In addition to transmitting audio and video, WHDI technology also provides a 100K return channel. The purpose of setting up this return channel is to enable the HDCP control protocol to verify each other between the transmitter and the receiver. At present, the domestic WHDI module manufacturer Shimeng Company has realized the return function of USB keyboard and mouse through this channel, namely UWTC (USB Wireless Transmission Control) technology, and has mastered the multi-touch remote control technology.

Support HDCP2.0 technology

　　The HDCP organization has set the HDCP2.0 technical standard for WHDI technology. HDCP2.0 allows users to implement one-to-many and many-to-many HDCP interactive authentication through WHDI technology. That is, HDCP2.0 technology allows a video source with a content protection protocol to be displayed on multiple display terminals at the same time. This is completely impossible to achieve in the HDMI1.2 standard.