2026-07-27T03:51:11Z https://drops.dagstuhl.de/oai

oai:drops-oai.dagstuhl.de:25594 2026-06-23T12:09:54Z ddc:004 open_access

Tight Loops, Smooth Streams: Responsive Congestion Control for Real-Time Video Karimi, Pantea Fouladi, Sadjad Sivaraman, Vibhaalakshmi Alizadeh, Mohammad real-time video congestion control transport protocols video rate control low-latency video communication tight feedback loop Real-time video streaming relies on rate control to match video bitrate to network capacity while keeping latency low. Existing deployed video rate controllers react slowly to network changes, causing under-utilization and latency spikes. In contrast, modern delay-sensitive congestion control algorithms (CCAs) adapt on round-trip-time timescales, maintaining a tight feedback loop that achieves both high utilization and low latency. We introduce Vidaptive, a lightweight framework that enables real-time video to leverage responsive CCAs without codec changes. Vidaptive decouples encoding from transmission: it paces video frames at the CCA’s rate and injects dummy packets when the encoder output is insufficient, preserving a continuous feedback loop. An online algorithm dynamically adjusts the encoder’s target bitrate to align with CCA capacity while bounding frame latency. Implemented in Google WebRTC, Vidaptive improves both video quality and tail latency on diverse cellular traces. Compared to GCC, it delivers 1.5× higher bitrate, +40% VMAF, +1.4 dB SSIM, +1.3 dB PSNR, and reduces 95th-percentile frame latency by 57% (2.2 seconds). Against Salsify, it achieves lower tail latency without invasive codec modifications. These results show that coupling existing CCAs with a thin adaptation layer can outperform specialized video rate controllers while remaining deployable in practice. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Pantea Karimi and Sadjad Fouladi and Vibhaalakshmi Sivaraman and Mohammad Alizadeh 2026 Is Part Of OASIcs, Volume 139, 1st New Ideas in Networked Systems (NINeS 2026) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/OASIcs.NINeS.2026.9 urn:nbn:de:0030-drops-255942 https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NINeS.2026.9 eng https://creativecommons.org/licenses/by/4.0/legalcode