Question

Users on a video endpoint report that during calls the far-end video periodically 'freezes' and displays blocky, smeared artifacts on the screen, while audio remains clear. The network team confirms that the audio and video traverse the same WAN link, and DSCP marking for video (AF41) and audio (EF) is applied correctly at the campus trust boundary. RTCP statistics from the endpoint show intermittent bursts of packet loss on the video stream only. What is the MOST likely root cause of the video artifacts?

Accepted Answer

Packet loss is corrupting reference frames, so the decoder cannot reconstruct subsequent inter-frames until the next IDR/keyframe arrives

Answer

Excessive one-way delay is exceeding the endpoint's de-jitter buffer causing audio to be dropped before video

Answer

The video stream is marked EF instead of AF41, so it is being policed by the LLQ priority queue

Answer

Asymmetric NAT is preventing the video RTP media path from establishing in both directions