`` Salsify '' that can deliver video in real time with higher quality and less delay than Skype and FaceTime
Stanford unveiled Salsify , a new real-time video delivery technology that surpasses real-time video applications such as
Salsify — A New Architecture for Real-time Internet Video
https://snr.stanford.edu/salsify/
Salsify: Low-Latency Network Video through Tighter Integration between a Video Codec and a Transport Protocol
https://www.usenix.org/system/files/conference/nsdi18/nsdi18-fouladi.pdf
GitHub-excamera / alfalfa: Purely functional video codec, used for ExCamera and Salsify
https://github.com/topics/video
The graph below shows SSIM evaluation (vertical axis) and delay (horizontal axis) of Salsify, WebRTC, WebRTC (when using VP9 / H.264 SVC ), FaceTime, Skype, and Hangouts . You can see that Salsify outperforms other technologies in both, meaning that the higher the quality is, the lower the delay is.
In addition, the following movie is a comparison of real-time movie distribution with Salsify and WebRTC on Google Chrome. When the network conditions worsen, both Salsify and WebRTC are becoming clumsy, but Salsify can clearly see that video recovery is faster than WebRTC.
Salsify vs. WebRTC-YouTube
Real-time video applications consist of two main components: a video codec that compresses movies and a transport protocol that sends packets of data and estimates the amount of transmission without overloading the network. These components are individually designed by the enterprise and are used in applications such as Skaype and FaceTime.
The transport protocol includes “ congestion control ” that tries to determine the speed of the network, and the video codec includes a “rate control” algorithm that tries to match the compressed movie with the instructions of the transport protocol. It is. According to the technology so far, there was a case where satisfactory performance could not be obtained on an unpredictable network when combining congestion control and rate control.
So, with Salsify, it is possible to recover video delivery immediately even if the network communication situation deteriorates by performing two controls simultaneously in one control loop. By applying this Salsify technology, for example, you can expect smooth video chatting regardless of communication conditions.
However, at the time of article creation, Salsify can only distribute video, and it is impossible to distribute audio data together. Also, the implementation itself is only for Linux, and it seems that it has not been implemented on Windows / macOS. The research team said, “The announced project is worth demonstrating the benefits of designing Salsify and allowing many researchers and companies to replicate the results,” many by incorporating the ideas of Salsify Suppose your application is intended to improve the quality of real-time video distribution.
A detailed presentation of Salsify by Stanford University's research team can be seen in the following movie.
Salsify: A New Architecture for Real-time Internet Video-YouTube
Salsify was originally started with an old project called “ ALFalfa ” for using application layer framing , and was designed to control the congestion control scheme “ Sprout ” used in ALFalfa jointly with rate control. The name “Salsify” comes from the same edible plant salsify ( Western burdock ) as alfalfa and sprout .
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