QP Selection Optimization for Intra-Frame Encoding Based on Constant Perceptual Quality

Chao WANG; Xuanqin MOU; Lei ZHANG

doi:10.1587/transinf.2015EDP7183

QP Selection Optimization for Intra-Frame Encoding Based on Constant Perceptual Quality

Chao WANG, Xuanqin MOU, Lei ZHANG

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In lossy image/video encoding, there is a compromise between the number of bits and the extent of distortion. Optimizing the allocation of bits to different sources, such as frames or blocks, can improve the encoding performance. In intra-frame encoding, due to the dependency among macro blocks (MBs) introduced by intra prediction, the optimization of bit allocation to the MBs usually has high complexity. So far, no practical optimal bit allocation methods for intra-frame encoding exist, and the commonly used method for intra-frame encoding is the fixed-QP method. We suggest that the QP selection inside an image/a frame can be optimized by aiming at the constant perceptual quality (CPQ). We proposed an iteration-based bit allocation scheme for H.264/AVC intra-frame encoding, in which all the local areas (which is defined by a group of MBs (GOMBs) in this paper) in the frame are encoded to have approximately the same perceptual quality. The SSIM index is used to measure the perceptual quality of the GOMBs. The experimental results show that the encoding performance on intra-frames can be improved greatly by the proposed method compared with the fixed-QP method. Furthermore, we show that the optimization on the intra-frame can bring benefits to the whole sequence encoding, since a better reference frame can improve the encoding of the subsequent frames. The proposed method has acceptable encoding complexity for offline applications.

Publication: IEICE TRANSACTIONS on Information Vol.E99-D No.2 pp.443-453

Publication Date: 2016/02/01

Publicized: 2015/11/17

Online ISSN: 1745-1361

DOI: 10.1587/transinf.2015EDP7183

Type of Manuscript: PAPER

Category: Image Processing and Video Processing

Authors

Chao WANG
  Xi'an Jiaotong University
Xuanqin MOU
  Xi'an Jiaotong University
Lei ZHANG
  The Hong Kong Polytechnic University

Keyword

bit allocation optimization, intra-frame encoding, constant quality, perceptual video coding

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Chao WANG, Xuanqin MOU, Lei ZHANG, "QP Selection Optimization for Intra-Frame Encoding Based on Constant Perceptual Quality" in IEICE TRANSACTIONS on Information, vol. E99-D, no. 2, pp. 443-453, February 2016, doi: 10.1587/transinf.2015EDP7183.
Abstract: In lossy image/video encoding, there is a compromise between the number of bits and the extent of distortion. Optimizing the allocation of bits to different sources, such as frames or blocks, can improve the encoding performance. In intra-frame encoding, due to the dependency among macro blocks (MBs) introduced by intra prediction, the optimization of bit allocation to the MBs usually has high complexity. So far, no practical optimal bit allocation methods for intra-frame encoding exist, and the commonly used method for intra-frame encoding is the fixed-QP method. We suggest that the QP selection inside an image/a frame can be optimized by aiming at the constant perceptual quality (CPQ). We proposed an iteration-based bit allocation scheme for H.264/AVC intra-frame encoding, in which all the local areas (which is defined by a group of MBs (GOMBs) in this paper) in the frame are encoded to have approximately the same perceptual quality. The SSIM index is used to measure the perceptual quality of the GOMBs. The experimental results show that the encoding performance on intra-frames can be improved greatly by the proposed method compared with the fixed-QP method. Furthermore, we show that the optimization on the intra-frame can bring benefits to the whole sequence encoding, since a better reference frame can improve the encoding of the subsequent frames. The proposed method has acceptable encoding complexity for offline applications.
URL: https://global.ieice.org/en_transactions/information/10.1587/transinf.2015EDP7183/_p

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@ARTICLE{e99-d_2_443,
author={Chao WANG, Xuanqin MOU, Lei ZHANG, },
journal={IEICE TRANSACTIONS on Information},
title={QP Selection Optimization for Intra-Frame Encoding Based on Constant Perceptual Quality},
year={2016},
volume={E99-D},
number={2},
pages={443-453},
abstract={In lossy image/video encoding, there is a compromise between the number of bits and the extent of distortion. Optimizing the allocation of bits to different sources, such as frames or blocks, can improve the encoding performance. In intra-frame encoding, due to the dependency among macro blocks (MBs) introduced by intra prediction, the optimization of bit allocation to the MBs usually has high complexity. So far, no practical optimal bit allocation methods for intra-frame encoding exist, and the commonly used method for intra-frame encoding is the fixed-QP method. We suggest that the QP selection inside an image/a frame can be optimized by aiming at the constant perceptual quality (CPQ). We proposed an iteration-based bit allocation scheme for H.264/AVC intra-frame encoding, in which all the local areas (which is defined by a group of MBs (GOMBs) in this paper) in the frame are encoded to have approximately the same perceptual quality. The SSIM index is used to measure the perceptual quality of the GOMBs. The experimental results show that the encoding performance on intra-frames can be improved greatly by the proposed method compared with the fixed-QP method. Furthermore, we show that the optimization on the intra-frame can bring benefits to the whole sequence encoding, since a better reference frame can improve the encoding of the subsequent frames. The proposed method has acceptable encoding complexity for offline applications.},
keywords={},
doi={10.1587/transinf.2015EDP7183},
ISSN={1745-1361},
month={February},}

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TY - JOUR
TI - QP Selection Optimization for Intra-Frame Encoding Based on Constant Perceptual Quality
T2 - IEICE TRANSACTIONS on Information
SP - 443
EP - 453
AU - Chao WANG
AU - Xuanqin MOU
AU - Lei ZHANG
PY - 2016
DO - 10.1587/transinf.2015EDP7183
JO - IEICE TRANSACTIONS on Information
SN - 1745-1361
VL - E99-D
IS - 2
JA - IEICE TRANSACTIONS on Information
Y1 - February 2016
AB - In lossy image/video encoding, there is a compromise between the number of bits and the extent of distortion. Optimizing the allocation of bits to different sources, such as frames or blocks, can improve the encoding performance. In intra-frame encoding, due to the dependency among macro blocks (MBs) introduced by intra prediction, the optimization of bit allocation to the MBs usually has high complexity. So far, no practical optimal bit allocation methods for intra-frame encoding exist, and the commonly used method for intra-frame encoding is the fixed-QP method. We suggest that the QP selection inside an image/a frame can be optimized by aiming at the constant perceptual quality (CPQ). We proposed an iteration-based bit allocation scheme for H.264/AVC intra-frame encoding, in which all the local areas (which is defined by a group of MBs (GOMBs) in this paper) in the frame are encoded to have approximately the same perceptual quality. The SSIM index is used to measure the perceptual quality of the GOMBs. The experimental results show that the encoding performance on intra-frames can be improved greatly by the proposed method compared with the fixed-QP method. Furthermore, we show that the optimization on the intra-frame can bring benefits to the whole sequence encoding, since a better reference frame can improve the encoding of the subsequent frames. The proposed method has acceptable encoding complexity for offline applications.
ER -