Quality-Driven Variable Frame-Rate for Green Video Coding in Broadcast Applications

Abstract

The Digital Video Broadcasting (DVB) has proposed to introduce the Ultra-High Definition services in three phases: UHD-1 phase 1, UHD-1 phase 2 and UHD-2. The UHD-1 phase 2 specification includes several new features such as High Dynamic Range (HDR) and High Frame-Rate (HFR). It has been shown in several studies that HFR (+100 fps) enhances the perceptual quality and that this quality enhancement is contentdependent. On the other hand, HFR brings several challenges to the transmission chain including codec complexity increase and bit-rate overhead, which may delay or even prevent its deployment in the broadcast echo-system. In this paper, we propose a Variable Frame Rate (VFR) solution to determine the minimum (critical) frame-rate that preserves the perceived video quality of HFR video. The frame-rate determination is modeled as a 3-class classification problem which consists in dynamically and locally selecting one frame-rate among three: 30, 60 and 120 frames per second. Two random forests classifiers are trained with a ground truth carefully built by experts for this purpose. The subjective results conducted on ten HFR video contents, not included in the training set, clearly show the efficiency of the proposed solution enabling to locally determine the lowest possible frame-rate while preserving the quality of the HFR content. Moreover, our VFR solution enables significant bit-rate savings and complexity reductions at both encoder and decoder sides.

Video Decoding Energy Reduction Using Temporal-Domain Filtering

“…Furthermore, considering the frame rate, it is well known that lower frame rates lead to a reduced power consumption on versatile devices [12,16], but the amount of savings was not assessed. In [17], it was shown that depending on the video content, optimal frame rate estimates can be obtained to optimize the rate-distortion performance, however, the impact on the energy consumption was not discussed.…”

“…Frame rate reduction is mostly performed by frame averaging [17]. The reason is that using frame averaging, a capturing process is simulated where the shutter angle is maximized.…”