A web-based user survey for evaluating power saving strategies for deaf users of mobileASL

  • Authors:

  • Jessica J. Tran;Tressa W. Johnson;Joy Kim;Rafael Rodriguez;Sheri Yin;Eve A. Riskin;Richard E. Ladner;Jacob O. Wobbrock

  • Affiliations:

  • University of Washington, Seattle, WA, USA;University of Washington, Seattle, WA, USA;University of Washington, Seattle, WA, USA;University of Washington, Seattle, WA, USA;University of Washington, Seattle, WA, USA;University of Washington, Seattle, WA, USA;University of Washington, Seattle, WA, USA;University of Washington, Seattle, WA, USA

  • Venue:
  • Proceedings of the 12th international ACM SIGACCESS conference on Computers and accessibility
  • Year:
  • 2010

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Abstract

MobileASL is a video compression project for two-way, real-time video communication on cell phones, allowing Deaf people to communicate in the language most accessible to them, American Sign Language. Unfortunately, running MobileASL quickly depletes a full battery charge in a few hours. Previous work on MobileASL investigated a method called variable frame rate (VFR) to increase the battery duration. We expand on this previous work by creating two new power saving algorithms, variable spatial resolution (VSR), and the application of both VFR and VSR. These algorithms extend the battery life by altering the temporal and/or spatial resolutions of video transmitted on MobileASL. We found that implementing only VFR extended the battery life from 284 minutes to 307 minutes; implementing only VSR extended the battery life to 306 minutes, and implementing both VFR and VSR extended the battery life to 315 minutes. We evaluated all three algorithms by creating a linguistically accessible online survey to investigate Deaf people's perceptions of video quality when these algorithms were applied. In our survey results, we found that VFR produces perceived video choppiness and VSR produces perceived video blurriness; however, a surprising finding was that when both VFR and VSR are used together, they largely ameliorate the choppiness and blurriness perceived, i.e., they each improve the use of the other. This is a useful finding because using VFR and VSR together saves the most battery life.