Experiments on Wave Driven Flow / Open Source Video Compression Technology


Sean Laguna and Jason Garrett-Glaser
Thursday, March 3, 2011
4:15 PM – 5:30 PM
Galileo Pryne

This week, there are two colloquium talks from current Mudd students.

Experiments on Wave Driven Flow through Emergent Vegetation Using a Quarter-Scale Model — Sean Laguna, Mudd CS Major


A quarter-scale model was used to extend a large-scale experiment measuring the energy reduction of wind-driven waves by emergent vegetation. The large-scale experiment is being performed at the O. H. Hinsdale Wave Research Laboratory at Oregon State University. The scale model experiment was performed to determine the reduction of wave height of wind-driven waves due to emergent vegetation, in response to changes in stem density. We measured the wave height for 6 independent waves at 11 positions within a 160 cm bed of vegetation, for 4 different stem densities. From this data, we produced curves describing the wave height decay for each stem density, and calculated the drag coefficient of the vegetation and the Reynolds number of the system. Results for two separate wave heights indicate that the correlation between the wave height decay coefficient of the produced curves, and stem density, is linear. Additionally, the calculated drag coefficients and Reynolds numbers lie ! near but outside the range of values found by previous experiments, providing new information about the correlation between the drag coefficient and Reynolds number. These results supplement results from the large-scale experiment, and allow the large-scale experiment to assume a linear relationship between the decay coefficient and stem density for its range of stem densities.

Open Source Video Compression Technology — Jason Garrett-Glaser, Mudd CS Major, Leader of the x264 project


Today, video is a multi-billion dollar industry including sites like Youtube and Facebook, streaming services like Netflix and Hulu, disc media like Blu-ray and DVD, and tens of thousands of television channels worldwide. All of this depends heavily on compression technology — without it, a 2 hour 1080p movie would be about 1 terabyte instead of the 5-15 gigabytes we’re more used to. A small improvement in compression can save hundreds of millions of dollars in bandwidth.

x264 has been incredibly successful over the past few years. Today it is, by many measurements, the world’s best video compression application. It is used by thousands of video websites and hundreds of television channels, as well as in many user-facing applications. In the past year, it’s made inroads in the movie market as well, with many x264-created Blu-ray videos being released commercially in the past few months.

In this talk, Jason will cover how he got into open source and x264’s open source development development process, a quick introduction to the basics of video compression, one of the many interesting algorithms he has invented, and finally some ways you can get involved in and benefit from the opportunities that open source offers.