Focus on Performance: Low Latency Video Streaming
04.10.2020 | Soliton Blog
Every stream you share out onto the world has a direct impact on the reputation of you as a professional and as a business. Your audience will judge factors like video quality and low latency. To put the best foot forward, you want to break down all the aspects of a good stream and tweak it to perfection. Interactive streams will want to focus on low latency the most.
What Causes Latency when Transmitting Video?
Several factors affect the latency when transmitting video, including the network speed/type, the components used from glass-to-glass, the video codec being used, and processes such as error correcting. Due to constant interference from radio frequencies, wireless network environments such as Wi-Fi and mobile are more likely to experience fluctuations in network stability than wired connections, resulting in frequent reductions in speed and signal loss, especially while moving. Each component used to transmit video is also important. The camera, encoder, decoder, and display all affect the total latency from glass-to-glass, and higher quality equipment results in lower latency. The type of error correcting like ARQ or FEC also affects the latency.
Latency measures the delay between the live recording and what the viewers see. This means anything that requires interaction, such as video games or Q&A sessions, needs as low latency as possible.
To get this, first attempt to work with these 5 factors to help lower your latency.
Higher bandwidth means less congestion in your connection, which can smooth out your latency. Pumping up your bandwidth is a simple addition to help with latency. The only limiting factor for this method is cost and the risk of unused bandwidth.
- Connection Type
A wired connection always gives a more stable connection compared to wireless. This stability can keep your latency from spiking.Fiber optics is one of the fastest video connections available on the market. Access to this will be a big boost for low latency.
Optimizing your encoder to work best with your network connection is one of the biggest factors for low latency. We here at Soliton provide some of the fastest encoders on the market, each of them capable of pushing high quality without disrupting latency.
- Video Format
Large file sizes and formats can push your latency the most. This is why often the easiest choice for low latency is to sacrifice video quality.Finding the right balance between how high you can push quality while keeping low latency will be the biggest trick for low latency streams.
Sometimes the distance can be a factor for low latency. This makes mobile streaming harder. If possible, reduce the distance between your streaming location and your internet hub.
Optimizing your encoder is often the biggest factor for low latency. To do this, you need to understand which streaming protocols you use for your connection. Depending on your provider and the encoder, you have 4 major choices.
Developed by Google in 2011, WebRTC focuses on pure speed. This can give you great latency but often sacrifices the video quality as a result. Due to the lower video quality, some CDNs may not work with WebRTC.
RTMP breaks down the video into more manageable chunks. Thanks to cloud technologies, it also scales better for bigger projects. There is a wide variety of RTMP available.
- HLS & DASH
HLS & DASH create streamable video segments from raw video footage. This middle man method works well but has trouble with larger video files.
FTL's design was to help work with interactive videos. It pushes for almost no latency for interactive purposes. The drawback is that you need to have a powerful internet connection and Mixer compatibility.
Soliton Transmission Protocol is as follows:
- From Field, encode with H.265 code
- Transmission with RASCOW
- Receive in Software, decode H.265
- RTMP or RTSP, Streaming to designated streaming server
What is Ultra-Low Latency Video Transmission?
Ultra-low latency video transmission is made possible via hardware/software that is optimized to process a very high volume of data packets with an extraordinarily low tolerance for delay (latency). The typical latency when transmitting video/audio over the mobile network is over 300ms. However, by utilizing higher quality equipment and better methods to transmit the video, latency lower than 100ms is achievable. Almost any existing use case for transmitting video can benefit from a lower latency. Also, many new applications that were not possible before is enabled by ultra-low latency video transmission technology.
Applications enabled with ultra-low latency technology:
- Real time broadcasting and content delivery
- Teleoperations requiring real time video streaming including:
o Remote control (such as robots)
o Remote driving (to support automated driving)
o Remote surgeries (telesurgery)
- Real time surveillance/monitoring (drones/wearable devices)
- Real time video conferencing
- Improvement of Real Time AI Image Processing
o Edge AI is limited in processing performance
By transmitting video to a cloud server with ultra low latency, highly accurate inference processing by a large scale neural network can be achieved
Peak Performance With Soliton
Soliton Systems offers Ultra-low Latency in our Smart-telecaster Zao-SH mobile encoder/transmitter unit, which enables a glass-to-glass transmission as low as 65ms over the cellular network. The Zao-SH achieves this ultra-low latency by utilizing the H.265 video codec along with our proprietary streaming protocol called RASCOW2. RASCOW2 is the successor to RASCOW1 which uses multilink (bonding) technology to bundle multiple network interfaces to transmit video while monitoring and dynamically adapting for uplink based on current network conditions. RASCOW2 is an improvement over RASCOW1 and dramatically reduces latency with parallel processing instead of the previous linear processing method.
We successfully participated in a 5G experiment with NTT Docomo and Komatsu and demonstrated remote operation over 5G at a recent DOCOMO Open House 2020 show in Tokyo.
Low latency is a big issue for interactive heavy streaming. Even tweaking one of these items can have major benefits and keep your streaming clean and useful. Working with the right equipment and providers will be the key to getting the low latency you need. For the best encoders on the market, look no further than Soliton. For more information on how we can help provide what you need, contact us today.