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Does Any Zero Latency Wireless HDMI 4K60? 

Does Any Zero Latency Wireless HDMI 4K60

Table of Contents

What's Video Latency?

Simply stated, video latency is the amount of time between the video captured and the video displayed. Different applications have different requirements for latency. Low latency is not critical for some applications, including set-top boxes, DVD players, and other media player devices, several seconds of latency is acceptable for those applications. 

However, real-time compression becomes crucial for some lag-sensitive video applications in which the latency between the video source and decoded video is extremely low, such as living streaming, HDM VR/AR, and Drone FPV, where the delay between the source and the displayed image must be kept low, latency measured in milliseconds instead of seconds.  Normally, making the latency less than 10ms is suitable for most applications,  we call such low latency “zero” latency.

Normally, there is zero latency for uncompressed video, the latency only exists  in compressed video. For uncompressed video and compressed video, please refers to our blog “Uncompressed Video vs Compressed Video“.

Please refer: 

https://en.wikipedia.org/wiki/Latency_(engineering)#Video

https://viewplaytek.com/uncompressed-video-vs-compressed-video

Latency Sensitive Applications

All wireless display applications demand low latency and consistency. For example, drone remote control depends on low-delay streaming of drone FPV. Game streaming with imperceptible latency is crucial to gaming performance. Moreover, users also require wire-like reliability, including consistent latency and smooth frame rate. Even an occasional freeze, delay, or frame drop in 1 or 2 minutes is annoying enough to disrupt the user experience. The characteristics and requirements of various wireless display applications are shown in the table below:

ApplicationNetwork technologyBandwidthError rateFrame rateLatency required
Drone first person view (FPV)OFDM, ISM, WiFi, 3/4/5GAs low as 2MbpsHigh60fps32ms
VR HMD game streaming802.11n/acAt least 50MbpsLow120fps16ms
2D game Streaming, MiraTouch802.11a/b/g/n/ac, Homeplug, LANVaraies between 5~40MbpsMedium60fps20ms
Wireless / remote desktop802.11a/b/g/n/ac, LANVaraies between 5~40MbpsLow30fps32ms

 

 

Latency Sensitive Applications

VR/AR HDM Application

Zero latency wireless HDMI solution is critical for the head-mounted display (HMD) for VR (virtual reality) or AR (augmented reality). To minimize motion sickness and other discomforts, the lag between when the user moves their head and when they see the result should be kept as short as possible. At the same, however, the lag shouldn’t cause inconvenience with the user’s ability to interact with the real world. Latencies for head-mounted displays can vary from milliseconds to seconds depending on the technology used. 

For example, according to Raaen and Kellmo, an acceptable level of visual response time is between 20 ms and 30 ms. Anything above this value causes a noticeable “blink” effect when moving around in the virtual environment.

 Drone FPV Application 

Latency is one of the most important details when using a FPV camera. The faster the processor, the lower the latency, and the better the control of the machine. If the latency between receiving an input from the drone and sending the output back to the drone is 100 milliseconds, then the drone will fly for 2 meters before the pilot notices it. Thus, if the drone loses control before the pilot notices it, the drone may crash into something.

Normally, the totally latency between camera to display should be within 50ms for drone FPV application. 

Wireless Gaming Application

Gaming also requires low latency or zero latency wireless HDMI encoding and decoding technology, 100ms or less is considered acceptable for gaming. However, 20-40ms is optimal, and low latency also ensures the user can control the game by the remote control, mouse, and game controller smoothly. 

 

What Causes Video Latency?

All Processing stages have latency as  below:

  • Video Compression (e.g. Motion-JPEG, H.264, H.265 )
  • Network Processing (e.g. RTP/UDP/IP Protocol)
  • Decoder Stream Buffer
  • Video Decompression (e.g. Motion-JPEG, H.264, H.265 )
  • Display

In early compression approaches, the encoding process starts when a complete video frame is present, this process takes at least 1 frame latency at the encoder and another 1 frame latency at the decode. by adding noise filtering and buffering, which can easily exceed 200ms latency between encoding and decoding.

Most existing solutions, like WiDi and Miracast, use low-delay implementations of the H.264 codec, designed for offline video compression. H.264 codec algorithm assumes the available bandwidth is known beforehand and there is no strict constraint on the instantaneous bandwidth. When applying h.264 for Internet video streaming, when the video packet is dropped, or the bandwidth is suddenly reduced, the receiving device can pause the video display for a short time to wait for video buffers accumulation before resuming playback.

However, the wireless display presents a completely different challenge. A user has no luxury of waiting. Most data communication networks such as WiFi or Ethernet LAN networks cannot guarantee the bandwidth or ensure the transmission is free of errors. While video buffers can improve reliability, it also increases latency. Therefore, it is very difficult to simultaneously ensure low latency and high reliability.

Viewplay Zero Latency Wireless HDMI Solution

The ViewPlay almost zero latency wireless HD solution has a unique advantage due to the joint optimization of hardware and software, thus delivering the HDMI cable experience with various networking technology, like WiFi, OFDM and Homeplug, etc. It consists of 3 major building blocks:

  1. Programmable video processor providing the flexibility and performance and required to
  2. Error resilient video codec algorithm
  3. Low-delay wireless display protocol

The Viewplay’s almost zero wireless HDMI solution reacts to real-time changing video complexity, network bandwidth and bitstream error with different video processing accordingly. It can meet the real-time requirements of compressing up to 480 million pixels each second with latency no more than 5 millisecond to deliver cable-like video at 4K resolution, even if there are packet losses. Moreover, our solution can adapt to drastic change in bandwidth. When the network can provide sufficient bandwidth, it can maximize visual quality. When the network bandwidth suddenly drops, it can quickly adapt its encoding bit rate with no delay to maintain smooth video playback.

The following table compares the performance of WiDi with Viewplay’ almost zero latency wireless HDMI solutions.

 

WiDi

TRX700

TRX900

Fabrication process

10nm

161nm

55nm

Resolution

1080p

1080p

4K60

End-to-end delay

<150ms

16ms

16ms

Error resilient

No

Yes

Yes

Multicasting

No

Yes

Yes

Connectivity

WiFi

WiFi, OFDM, Homeplug, Ethernet

WiFi, OFDM, Homeplug, Ethernet

Power consumption

n/a

1.5W

200mW

Our new zero latency wireless HDMI extender  (Model No.:WLU3434) adopt our latest private DSP technology that supports real-time HD video streaming with as low as 16ms delay, efficient bit rate control, and high stability.

It supports 4K 60p video, HDR, delivering stunningly clear images, rich detail, and amazing depth.

End-to-End latency is as low as 0-16 ms. It is the fastest and most stable wireless HD transmission technology available today, ideal for use in scenarios requiring low latencies, such VR, AR, and game development.

https://viewplaytek.com/wireless-4k-hdmi-transmitter-and-receiver-wlu3434/

 

Conclusion

ViewPlay’s almost zero latency wireless HDMI solution offers high performance for latency-sensitive applications, such as real-time streaming, including HDMI, Drone PFV,  and digital television broadcasting. It has zero latency capabilities which make it possible to implement these systems in new ways that allow natural interactiveness without losing video quality. 

 

 

 

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