Electrical and Electronics Engineering MS Thesis Defense by Gonca Bakar

KOÇ UNIVERSITY

GRADUATE SCHOOL OF SCIENCES & ENGINEERING

ELECTRICAL AND ELECTRONICS ENGINEERING

MS THESIS DEFENSE BY GONCA BAKAR

Title: Motion-Based Rate Control Using Scalable VP9 Video Coding for WebRTC Videoconferencing

Speaker: Gonca Bakar

Time: January 15, 2018, 10:00

Place: ENG B15

Koç University

Rumeli Feneri Yolu

Sariyer, Istanbul

Thesis Committee Members:

Prof. A. Murat Tekalp (Advisor, Koç University)

Assoc. Prof. Öznur Özkasap (Koç University)

Asst. Prof. Ali Cengiz Beğen (Özyeğin University)

Abstract:

WebRTC has become a popular platform for real-time communications (RTC) over the best-effort Internet. It employs the Google Congestion Control algorithm to obtain an estimate of the state of the network. The default configuration employs single-layer constant bitrate (CBR) video encoding given the available network rate with rate control achieved by varying the quantization parameter and video frame rate. Recently, some open-source WebRTC platforms provided support for VP9 encoding with spatial scalable encoding option. This thesis seeks to incorporate motion-based spatial resolution adaptation for adaptive rate control. For point-to-point solutions the use of proposed motion-based mixed spatio-temporal scalable VP9 encoding and single-layer (non-scalable) VP9 encoding and for multi-party RTC solutions scalable VP9 video coding based Selective Forwarding Unit (SFU) with and without motion-based layer selection are compared in the presence of network congestion. Our results show that spatial resolution reduction with sufficiently high frame rates and reasonable quantization parameter values yields more pleasing video quality during intervals of high motion activity, compared to the standard rate control scheme employed in open-source WebRTC implementations that use only quantization parameter and frame rate for rate control.