JVET-AK0193 Low latency Wi-Fi transmission simulation and suggestions on codec requirements [S. Ikonin, X. Ma, I. Gribushin, M. Sychev, V. Khamidullin, R. Shabaev, E. Alshina (Huawei)]

This contribution illustrates video transmission performance simulated using wireless Wi-Fi network simulator under low latency constraint. It is observed that average and worst case reconstructed quality, and frame freeze ratio strongly depend on the latency requirements specified in the test. With the transmission latency restricted to 16 ms, corresponding to one frame interval at 60 fps, the video freeze ratio is more than 20%, and average reconstruction quality is degraded by 5.0 dB (from 39.1 to 34.1 dB). Due to low latency restriction and wireless channel fluctuation decoder cannot be always guaranteed to receive all the packets necessary for frame reconstruction in time. It is suggested to consider packet loss resilient reconstruction as a necessary functionality to support low latency requirement.

Simulator uses a pattern for losses (using NS-3, similar concept as JVET-AK0057), but additionally allows generating losses based on latency. Encoding/decoding delay is currently not considered.

Error patterns of various network types could be used.

A video demo is included in the contribution.

At decoder, a lost slice is discarded. Encoder-side error concealment is used, changing reference picture of subsequent pictures based on feedback that a slice was lost. This would require the feedback channel to be reliable. Loss of I picture is not considered currently. Other approaches of error concealment might be useful to be studied.

It was commented by various experts that the topic of JVET-AK0057 and JVET-AK0193 is highly relevant.

It was requested to establish a new AHG (led by S. Ikonin) on ultra-low delay study.

Decision (SW): Create an AHG branch in VTM for the software of JVET-AK0057 and JVET-AK0193.