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SUMMARY:Unsynchronized Visual Communication  - Wenjun Hu (Yale University)
DTSTART:20140602T140000Z
DTEND:20140602T150000Z
UID:TALK51694@talks.cam.ac.uk
CONTACT:Eiko Yoneki
DESCRIPTION:As smartphone penetration continues to grow and displays are w
 idely available\, there are many opportunities to transmit information ove
 r screen-camera links in the form of a video of 2D barcodes. A key challen
 ge for smartphone based visual communication over screen-camera links is i
 mperfect frame synchronization. The difficulty arises from frame rate dive
 rsity and variability due to camera capability\, lighting conditions\, and
  system factors. If the transmit frame rate is too high\, the receiver mig
 ht lose original frames or capture mixed frames\, which are normally not d
 ecodable. Previous systems simply reduce the effective screen frame rate t
 o be half the camera frame capture rate. This under-utilizes the transmitt
 er side capacity and is inefficient.\n\nWe achieve frame synchronization w
 ith LightSync\, which features in-frame color tracking to decode imperfect
  frames and a linear erasure code across frames to recover lost frames. Li
 ghtSync allows smooth communication between the screen and the camera at a
 ny combination of the transmit and receive frame rates\, as long as the re
 ceive rate is at least half the transmit rate. This means that each receiv
 er can scale the decoding performance with its own camera capability. Acro
 ss several phones\, our system can more than double the average throughput
  compared to previous approaches.\n\nBio: Wenjun Hu is an assistant profes
 sor of Electrical Engineering and Computer Science at Yale University\, ba
 sed in the newly launched Yale Institute for Network Science. Until the en
 d of 2013\, she was a researcher at Microsoft Research Asia. Previously\, 
 she was a postdoctoral research associate at the University of Washington.
  She did her PhD with Prof. Jon Crowcroft at the University of Cambridge\,
  though spending about 7 months each at MIT CSAIL and Microsoft Research C
 ambridge during her PhD. Her work has mainly focused on building various w
 ireless systems\, including smartphone based visual communication\, wirele
 ss video\, MIMO\, and network coding in wireless mesh networks.\n
LOCATION:FW26\, Computer Laboratory\, William Gates Builiding
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