RTP/AVPF compliant feedback for error resilient video coding in conversational applications

Feedback-based error-resilient video coding relies on efficient transmission of feedback messages. The Audio-Visual Profile with Feedback (AVPF) for Real-time Transport Control Protocol (RTCP), i.e. RTP/AVPF, supports low-latency feedbacks. In this paper, a reference picture selection (RPS) method using RTP/AVPF-compliant feedback is proposed. A restriction period is first derived in the codec layer based on the previously transmitted back-channel message, the RTCP reporting interval, the round-trip time, and the processing delay of the encoder. Then, a feedback message is transmitted when the restriction period is passed and an incorrectly reconstructed picture is detected. At the encoder, the decoded picture buffer (DPB) is adaptively controlled to combat feedback delay fluctuation in RTP/AVPF. Simulation results show that the proposed entire solution outperforms traditional RPS, wherein a back-channel message is transmitted for every lost picture and the DPB is managed by sliding window.