Abstract
Adaptive live video streaming applications utilize a predefined
collection of bitrate-resolution pairs, known as a bitrate ladder, for
simplicity and efficiency, eliminating the need for additional run-time
to determine the optimal pairs for each video. These applications do not
incorporate two-pass encoding methods due to increased latency. However,
an optimized bitrate ladder could result in lower storage and delivery
costs and improved Quality of Experience (QoE). This paper presents a
Just Noticeable Difference (JND)-aware constrained Variable Bitrate
(cVBR) Two-pass Per-title encoding Scheme (JTPS) designed specifically
for live video streaming. JTPS predicts a content- and JND-aware bitrate
ladder using low-complexity features based on Discrete Cosine Transform
(DCT) energy and optimizes the constant rate factor (CRF) for each
representation. The effectiveness of JTPS is demonstrated using the x265
open-source video encoder, with an average bitrate reduction of 18.80%
and 32.59% for the same PSNR and VMAF, respectively, compared to the
standard HTTP Live Streaming (HLS) bitrate ladder using Constant Bitrate
(CBR) encoding. The implementation of JTPS also resulted in a 68.96%
reduction in storage space with a negligible impact on streaming
latency.