H.264 deblocking filter enhancement

Abstract

This paper proposes new software-based techniques for speeding and reducing the complexity of the deblocking filter used in the state-of-the-art H.264 international video coding standard to improve the visual quality of the decoded video frames. The proposed techniques are classified as standard compliant and standard-noncompliant techniques. The standard compliant techniques optimize the standard filter through optimizing the boundary strength calculation and group filtering of macroblocks. The standard-noncompliant techniques predict the new boundary strength and edge detection conditions from previous values. Experimental results on both an embedded platform and a desktop PC show significant increment in performance improvement that reaches 47% for the standard compliant techniques and 80% for the standard-noncompliant techniques. They also demonstrate that for standard noncompliant techniques the quality degradation computed using the Peak Signal to Noise Ratio is insignificant. The H.264/MPEG-4 A VC is the latest international video coding standard [1][2]. It is being used increasingly in several consumer electronics for a wide range of applications as video conferencing, digital video storing, video streaming, and video telephony. It uses state-of-the-art coding tools and provides superior coding efficiency. The superiority of coding efficiency is due to added features and functionalities as block-based processing, variable block-size mode selection, quarter-pixel motion compensation, and deblocking filter. On the other hand, these additions have resulted in a complexity that doubles that of the H.263. Another issue is that the block-based processing introduces visible blocking artifacts in flat regions and ringing artifacts along object edges in the reconstructed frames. [n general, the less the bit rate, the more severe is the manifest of the coding artifacts in the reconstructed video [3]. The deblocking filter is one important tool to increase the coding efficiency and significantly improve the decoded video quality of the H.264 by removing the blocking and ringing artifacts [4]. However, it significantly adds to the H.264 computational complexity and time consumption. Fig. 1 gives profiling results for an H.264 decoder. These results were obtained by running the H.264 baseline profile on the 978-1-4577-0128-3/11/$26.00

Optimal complexity scalable H.264/AVC video decoding scheme for portable multimedia devices

“…Lee et al 6 also worked towards complexity scalability by controlling the complexity of motion compensation and of the deblocking filter. Mahjoub et al 7 proposed a complexity reduction method of the deblocking filter, and Lu et al 8 optimized the context adaptive variable length coding (CAVLC) lookup tables to reduce the decoding complexity. de Oliveira et al 9 optimized the inverse transform (IT) matrix for each frame, as a function of both content and quantization noise.…”