Analyzing the intelligibility of real-time mobile sign language video transmitted below recommended standards

Jessica J. Tran, Ben Flowers, Eve A. Riskin, Richard E. Ladner, Jacob O. Wobbrock

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

13 Scopus citations

Abstract

Mobile sign language video communication has the potential to be more accessible and affordable if the current recommended video transmission standard of 25 frames per second at 100 kilobits per second (kbps) as prescribed in the International Telecommunication Standardization Sector (ITU-T) Q. 26/16 were relaxed. To investigate sign language video intelligibility at lower settings, we conducted a laboratory study, where fluent ASL signers in pairs held real-time free-form conversations over an experimental smartphone app transmitting real-time video at 5 fps/25 kbps, 10 fps/50 kbps, 15 fps/75 kbps, and 30 fps/150 kbps, settings well below the ITU-T standard that save both bandwidth and battery life. The aim of the laboratory study was to investigate how fluent ASL signers adapt to the lower video transmission rates, and to identify a lower threshold at which intelligible realtime conversations could be held. We gathered both subjective and objective measures from participants and calculated battery life drain. As expected, reducing the frame rate/bit rate monotonically extended the battery life. We discovered all participants were successful in holding intelligible conversations across all frame rates/bit rates. Participants did perceive the lower quality of video transmitted at 5 fps/25 kbps and felt that they were signing more slowly to compensate; however, participants' rate of fingerspelling did not actually decrease. This and other findings support our recommendation that intelligible mobile sign language conversations can occur at frame rates as low as 10 fps/50 kbps while optimizing resource consumption, video intelligibility, and user preferences.

Original languageEnglish
Title of host publicationASSETS14 - Proceedings of the 16th International ACM SIGACCESS Conference on Computers and Accessibility
Pages177-184
Number of pages8
ISBN (Electronic)9781450327206
DOIs
StatePublished - 20 Oct 2014
Event16th International ACM SIGACCESS Conference on Computers and Accessibility, ASSETS 2014 - Rochester, United States
Duration: 20 Oct 201422 Oct 2014

Publication series

NameASSETS14 - Proceedings of the 16th International ACM SIGACCESS Conference on Computers and Accessibility

Conference

Conference16th International ACM SIGACCESS Conference on Computers and Accessibility, ASSETS 2014
Country/TerritoryUnited States
CityRochester
Period20/10/1422/10/14

Keywords

  • American Sign Language
  • Bit rate
  • Comprehension
  • Deaf community
  • Frame rate
  • Intelligibility
  • Laboratory study
  • Video compression

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