Abstract - In video coding algorithm, a transform is one of the most important video compression tools. Transform converts residual signals into frequency domain data to get decorrelated signals. Decorrelated data using transforms is used for coding efficiency improvement in video compression. In this paper, an efficient transform selection method in term of video compression is described by using transform block size and intra coding mode on the top of the HEVC standard.
The H.264/AVC standard utilizes temporal prediction tools to obtain a good coding performance by reducing temporal redundancy between frames. However, because H.264/AVC does not efficiently encode video sequences that have a local illumination change, the coding performance of H.264/AVC is dropped when the local illumination changes occur in video. We propose an adaptive motion compensation method using neighboring pixels and motion vector refinement to efficiently encode the local illumination changes. By using the proposed method, we achieve a bit savings up to 6.86% with peak signal-to-noise-ratio gain compared to H.264/AVC.
We propose a rate-distortion optimized transform coding method that adaptively employs either integer cosine transform that is an integer-approximated version of discrete cosine transform (DCT) or integer sine transform (IST) in a rate-distortion sense. The DCT that has been adopted in most video-coding standards is known as a suboptimal substitute for the Karhunen-Loève transform. However, according to the correlation of a signal, an alternative transform can achieve higher coding efficiency. We introduce a discrete sine transform (DST) that achieves the high-energy compactness in a correlation coefficient range of −0.5 to 0.5 and is applied to the current design of H.264/AVC (advanced video coding). Moreover, to avoid the encoder and decoder mismatch and make the implementation simple, an IST that is an integer-approximated version of the DST is developed. The experimental results show that the proposed method achieves a Bjøntegaard Delta-RATE gain up to 5.49% compared to Joint model 11.0.
We propose a new image-downsampling method for interlaced-to-progressive transcoding. The proposed image-downsampling method is performed in the discrete cosine transform (DCT) domain. We develop a downsampling filter matrix that transcodes the interlaced picture into the progressive picture. The method shows a good peak signal-to-noise ratio (PSNR) compared with spatial-domain downsampling.
KEYWORDS: Quantization, Computer programming, Video, Video coding, Video compression, Sun, Associative arrays, Data compression, Motion estimation, Binary data
In this paper, we propose an adaptive entropy coding method to improve the VLC coding efficiency of H.26L TML-1 codec. First of all, we will show that the VLC coding presented in TML-1 does not satisfy the sibling property of entropy coding. Then, we will modify the coding method into the local statistics adaptive one to satisfy the property. The proposed method based on the local symbol statistics dynamically changes the mapping relationship between symbol and bit pattern in the VLC table according to sibling property. Note that the codewords in the VLC table of TML-1 codec is not changed. Since this changed mapping relationship also derived in the decoder side by using the decoded symbols, the proposed VLC coding method does not require any overhead information. The simulation results show that the proposed method gives about 30% and 37% reduction in average bit rate for MB type and CBP information, respectively.
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