Leveraging the Delay-Friendliness of TCP With FEC Coding in Real-Time Video Communication

Transmission control protocol (TCP) is pervasively employed as the transport-layer solution in popular video applications (e.g., Skype, Google+, HTTP-based adaptive video streaming, etc.) for firewall traversal and network-friendliness. To remedy the shortcomings of the data retransmission mechanism in TCP, forward error correction (FEC) coding is commonly used as the application-layer error-resilient scheme in live media streaming systems. An important measurement study reveals that TCP exhibits delay-friendliness (i.e., delay-performance bias) towards traffic flows composed of small-size packets. Motivated by leveraging the delay-friendliness of TCP to optimize the real-time streaming video quality, we propose a novel FEC coding scheme dubbed Coded Live vide OStreaming ov Er TCP (CLOSET). To achieve the optimal video quality over the lossy communication networks, we analytically formulate the constrained optimization problem of joint FEC coding and packet interleaving to minimize the effective packet loss rate. Then, we provide an approximate analysis to derive the solution for online adaption of FEC redundancy, packet size, and interleaving level. The performance of CLOSET is evaluated through extensive semi-physical emulations in Exata involving real-time encoded H.264 video streaming. Experimental results show that CLOSET outperforms the reference FEC coding schemes in terms of video peak signal-to-noise ratio (PSNR), end-to-end delay, ratio of overdue video frames, and goodput. Therefore, we recommend CLOSET for TCP-based real-time video communication systems.