FareQR: Fast and Reliable Screen-Camera Transfer System for Mobile Devices using QR Code

With the availability of mobile devices display and camera, Screen-Camera links for Visible Lite Communications (VLC) has attracted much more attention due to its convenience, infrastructure-free and security. In conventional Screen-camera link, the senders encode data bits into a barcode stream and receivers capture the barcode scream and decode the barcodes. But conventional Screen-camera communication systems all suffer from both CMOS rolling shutter and inter frame mixing problem when display rate is close to camera capture rate and this leads to a high block transfer error rate. In this paper, we propose a system called FareQR by adding an outline border to the barcode stream to help the receiver detect mixed frames and de-obfuscation each mixed frames into perfect QRCodes. We formulate the mixed frame de-obfuscation problem as a hard-decision-decoding task, and propose a Viterbi algorithm to resolve each block in the mixed areas. We test the FareQR and result demonstrate that our work can recover the mixed area and reduce the block transfer error rate.