  It is well known that high dynamic range (HDR) video can provide more
immersive visual experiences compared to conventional standard dynamic range
content. However, HDR content is typically more challenging to encode due to
the increased detail associated with the wider dynamic range. In this paper, we
improve HDR compression performance using the effective bit depth adaptation
approach (EBDA). This method reduces the effective bit depth of the original
video content before encoding and reconstructs the full bit depth using a
CNN-based up-sampling method at the decoder. In this work, we modify the MFRNet
network architecture to enable multiple frame processing, and the new network,
multi-frame MFRNet, has been integrated into the EBDA framework using two
Versatile Video Coding (VVC) host codecs: VTM 16.2 and the Fraunhofer Versatile
Video Encoder (VVenC 1.4.0). The proposed approach was evaluated under the JVET
HDR Common Test Conditions using the Random Access configuration. The results
show coding gains over both the original VVC VTM 16.2 and VVenC 1.4.0 (w/o
EBDA) on JVET HDR tested sequences, with average bitrate savings of 2.9% (over
VTM) and 4.8% (against VVenC) based on the Bjontegaard Delta measurement. The
source code of multi-frame MFRNet has been released at
https://github.com/fan-aaron-zhang/MF-MFRNet.
