Encoding, Fast and Slow: Low-Latency Video Processing Using Thousands of Tiny Threads

Sadjad Fouladi, Riad S. Wahby, and Brennan Shacklett, Stanford University; Karthikeyan Vasuki Balasubramaniam, University of California, San Diego; William Zeng, Stanford University; Rahul Bhalerao, University of California, San Diego; Anirudh Sivaraman, Massachusetts Institute of Technology; George Porter, University of California, San Diego; Keith Winstein, Stanford University


We describe ExCamera, a system that can edit, transform, and encode a video, including 4K and VR material, with low latency. The system makes two major contributions.

First, we designed a framework to run general-purpose parallel computations on a commercial “cloud function” service. The system starts up thousands of threads in seconds and manages inter-thread communication.

Second, we implemented a video encoder intended for fine-grained parallelism, using a functional-programming style that allows computation to be split into thousands of tiny tasks without harming compression efficiency. Our design reflects a key insight: the work of video encoding can be divided into fast and slow parts, with the “slow” work done in parallel, and only “fast” work done serially.

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@inproceedings {201559,
author = {Sadjad Fouladi and Riad S. Wahby and Brennan Shacklett and Karthikeyan Vasuki Balasubramaniam and William Zeng and Rahul Bhalerao and Anirudh Sivaraman and George Porter and Keith Winstein},
title = {Encoding, Fast and Slow: Low-Latency Video Processing Using Thousands of Tiny Threads},
booktitle = {14th {USENIX} Symposium on Networked Systems Design and Implementation ({NSDI} 17)},
year = {2017},
isbn = {978-1-931971-37-9},
address = {Boston, MA},
pages = {363--376},
url = {https://www.usenix.org/conference/nsdi17/technical-sessions/presentation/fouladi},
publisher = {{USENIX} Association},