JVET-AO0047 AHG18: Simulation software for ULL CTC JVET-AN2039 [V. Khamidullin, K. Malyshev, I. Gribushin, M. Sychev, S. Ikonin, E. Alshina (Huawei)]
This contribution describes the simulation software submitted for AGH18 on ultra-low latency and packet loss resilience based on contribution JVET-AN2039. The purpose of this document is to give an introduction and help to be familiar with software. The document describes main modifications of encoder and decoder applications of VTM, entry point for network transmission emulation, and basic logic of main modules. The software also includes the fixes of JVET-AN0081 approved by 40th JVET meeting. The software is available as a branch at https://vcgit.hhi.fraunhofer.de/jvet-ahg-ull/VVCSoftware_VTM/-/tree/jvet-an2039.
The software consists of a modified VTM (encoder and decoder). It is using a trace file that is coming from an external network simulator. The trace file is used to drop NAL units from the bitstream (currently simulated by jitter buffer in the encoder application). The decoder receives a modified stream where NAL units ar missing, but has been modified in a way that it does not crash and conducts a concealment (frame freezing until a full set of reference pictures is available).
For the unicast application, feedback is generated from the jitter buffer such that the encoder is aware of lost frames, and can update the bitstream accordingly.
For the broadcast application (no feedback), one option is using a scalable stream, where base layer packets get priority in transmission.
It was asked if FEC has been used? This was not the case. In principle, this could be implemented, but for that purpose it would be better to decouple network packetization from the encoder.
It was also commented that some mechanisms that are currently under discussion in the network community for the benefit of low latency applications, are not yet readily developed.
Decision (SW): include JVET-AO0047 in AHG18 software