GAN-based Effective Bit Depth Adaptation for Perceptual Video Compression

Resolution and effective bit depth (EBD) adaptation have been recently utilised in video compression to improve coding efficiency. This type of approach dynamically reduces spatial/temporal resolutions and effective bit depth at the encoder and restores the original video formats during decoding. In this paper, a convolutional neural networks (CNN) based EBD adaptation method is presented for perceptual video compression, in which the employed CNN models are trained using a generative adversarial network (GAN), with perception-based loss functions. This method was integrated into the HEVC HM 16.20 reference software and fully evaluated on test sequences from the JVET Common Test Conditions using the Random Access configuration. The results show significant coding gains achieved on all test sequences with an overall bit rate saving of 24.8% (Bjontegaard Delta measurement) based on a perceptual quality metric, VMAF.