1,526 research outputs found
An efficient rate control algorithm for a wavelet video codec
Rate control plays an essential role in video coding and transmission to provide the best video quality at the receiver's end given the constraint of certain network conditions. In this paper, a rate control algorithm using the Quality Factor (QF) optimization method is proposed for the wavelet-based video codec and implemented on an open source Dirac video encoder. A mathematical model which we call Rate-QF (R - QF) model is derived to generate the optimum QF for the current coding frame according to the target bitrate. The proposed algorithm is a complete one pass process and does not require complex mathematical calculation. The process of calculating the QF is quite simple and further calculation is not required for each coded frame. The experimental results show that the proposed algorithm can control the bitrate precisely (within 1% of target bitrate in average). Moreover, the variation of bitrate over each Group of Pictures (GOPs) is lower than that of H.264. This is an advantage in preventing the buffer overflow and underflow for real-time multimedia data streaming
JND-Based Perceptual Video Coding for 4:4:4 Screen Content Data in HEVC
The JCT-VC standardized Screen Content Coding (SCC) extension in the HEVC HM
RExt + SCM reference codec offers an impressive coding efficiency performance
when compared with HM RExt alone; however, it is not significantly perceptually
optimized. For instance, it does not include advanced HVS-based perceptual
coding methods, such as JND-based spatiotemporal masking schemes. In this
paper, we propose a novel JND-based perceptual video coding technique for HM
RExt + SCM. The proposed method is designed to further improve the compression
performance of HM RExt + SCM when applied to YCbCr 4:4:4 SC video data. In the
proposed technique, luminance masking and chrominance masking are exploited to
perceptually adjust the Quantization Step Size (QStep) at the Coding Block (CB)
level. Compared with HM RExt 16.10 + SCM 8.0, the proposed method considerably
reduces bitrates (Kbps), with a maximum reduction of 48.3%. In addition to
this, the subjective evaluations reveal that SC-PAQ achieves visually lossless
coding at very low bitrates.Comment: Preprint: 2018 IEEE International Conference on Acoustics, Speech and
Signal Processing (ICASSP 2018
An efficient rate control algorithm for a wavelet video codec
Rate control plays an essential role in video coding and transmission to provide the best video quality at the receiver's end given the constraint of certain network conditions. In this paper, a rate control algorithm using the Quality Factor (QF) optimization method is proposed for the wavelet-based video codec and implemented on an open source Dirac video encoder. A mathematical model which we call Rate-QF (R - QF) model is derived to generate the optimum QF for the current coding frame according to the target bitrate. The proposed algorithm is a complete one pass process and does not require complex mathematical calculation. The process of calculating the QF is quite simple and further calculation is not required for each coded frame. The experimental results show that the proposed algorithm can control the bitrate precisely (within 1% of target bitrate in average). Moreover, the variation of bitrate over each Group of Pictures (GOPs) is lower than that of H.264. This is an advantage in preventing the buffer overflow and underflow for real-time multimedia data streaming
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