RTP anti-loss packet transmission scheme

UDP-based RTP transmission in the complex public network environment, especially 3G, 4G, WiFi network faced with packet loss, disorderly sequence, repetition, jitter and other issues, seriously affect the real-time audio and video interactive effect, even if it is a RTP packet lost, if the receiver does not do processing, will also lead to the appearance of video mosaic, This scheme uses a variety of methods to solve the problem of UDP transmission video packet loss, including video receiver end jitter buffer processing packet chaos/repetition problem, FEC (forward error correction) Priority Packet Recovery, And when FEC can not recover the lost packets using packet retransmission policy request retransmission packet, if the retransmission still has packet loss situation, the decoding end does not decode (possibly huaping), the direct request sender sends I frame, these several ways combination, in practice can effectively avoid drops caused by the flower screen, lag phenomenon, By adjusting the FEC redundancy, the processing of different packet loss rates can be achieved.

Here FEC forward error correction technology has been widely used, the approximate principle is that every K media packets issued, using this K media packets to generate n-k redundant packets, where n is the sum of media packets and packets, the receiving end as long as the received K packets (including media packets and redundant packets), You can recover any of the missing media packets in the K media pack.