Browsing by Author "Wang, CN"

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A complexity aware variable-bit-depth motion estimation
(2005)
Wang, SH
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Wang, CN
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Chiang, TH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Demands for using different complexity level algorithms to deliver multimedia content delivery over portable devices are increasing thanks to advanced battery technology. This paper describes a novel complexity aware motion estimation for H.264 based on pixel representation of different bit-depth and a simple scene change detection module. The experimental results show that with identical searching complexity, improvement on averaged PSNR is more than 0.2dB for 4-bit representation and more than 2 dB for 1/2-bit representation as compared to conventional bit-truncation method.
A fast audio bit allocation technique based on a linear R-D model
(2002-08-01)
Lee, CY
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Fang, YC
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Chuang, HC
;
Wang, CN
;
Chiang, T
The MPEG-1 Layer III audio coding is most widespread digital audio format on the Internet. Its encoder is more complicated than the other layers., in the MPEG-I audio specification, where the bit allocation constitutes significant part of the total computational load. This paper describes a fast bit allocation technique using a novel linear model to compute the bitrate and the global gain of the inner loop (rate control loop) for the classic MP3 bit allocation problem. Estimated quantization noise is approximated with a binomial expansion for the adjustment of the scalefactors. This procedure reduces the outer loop iterations (distortion control loop) to one loop. Our bit allocation technique is about five times faster compared to the well-known LAME MP3 encoder. Based on the objective quality measure, total number of distorted bands, and average total noise-to-masking ratio (NMR), our experimental results show that there is significant improvement in speedup of the encoding process without noticeable audio quality degradation.
A fast audio bit allocation technique based on a linear R-D model
(2002-01-01)
Lee, CY
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Fang, YC
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Chuang, HC
;
Wang, CN
;
Chiang, TH
This paper describes a fast bit allocation technique using a novel linear model for the bitrate and the global gain of the inner loop in the classic MP3 bit allocation. The outer loop is approximated with a binomial expansion. Our technique is five times faster compared to the LAME MP3 encoder.
A fast downsizing video transcoder based on H.264/AVC standard
(2004)
Li, CH
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Wang, CN
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Chiang, TH
;
交大名義發表
;
National Chiao Tung University
This paper presents a novel spatial transcoding technique for H.264/AVC based video applications. With superior coding performance, H.264 will be used in a variety of multimedia applications. For various video applications, spatial transcoding techniques can facilitate compact storage of video sequences with specified resolution and bitstrem format. Under demands, we can convert the archival bitstreams to another bitstream with different bitrates and different. resolution before transmission. For H.264 video transmission that needs spatial resolution conversion, we propose a bottom-up motion vector re-estimation, rapid rate-distortion (R-D) optimized mode decision. and adaptive motion search range to speed up the spatial transcoding and retain visual quality of transcoded video. The results show that the fast transcoder has the R-D performance close to or better than R-D re-encoding algorithm. which has the highest complexity and best coding efficiency.
A fast H.264-based picture-in-picture (PIP) transcoder
(2004)
Li, CH
;
Lin, H
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Wang, CN
;
Chiang, T
;
電子工程學系及電子研究所
The paper presents a novel and fast transcoding scheme with PIP (Picture-in-Picture) functionality based on H.264/AVC standard. We seamlessly achieve significant speedup and maintain identical video quality for the composite video content using two H.264 bitstreams. The proposed Partial Re-Encoding transcoder (PRET) method based on the intra-prediction refinement, inter-prediction refinement and rate-distortion optimization has sped up by 8 times for with rate-distortion (R-D) based optimization. In addition, the performance of the PRET is better than that of R-D re-encoding algorithm.
A hierarchical decimation lattice based on N-queen with an application for motion estimation
(2003-08-01)
Wang, CN
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Yang, SW
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Liu, CM
;
Chiang, TH
;
資訊科學與工程研究所
We present a novel technique, N-queen lattice, to spatially subsample a block of pixels. Although this lattice is pertinent to many applications, we present an application to speed up motion estimation with minimal loss of coding efficiency. The N-queen lattice is constructed to characterize spatial features in all directions. It can be hierarchically organized for motion estimation With variable nonsquare block size. Despite the randomized lattice structure, we demonstrate that it is possible to achieve compact data storage architecture for efficient memory access and simple hardware implementation. Our simulations show that the N-queen lattice is superior to several existing sampling techniques with improvement in speed by about N times and small loss. in peak SNR.
A hierarchical N-queen decimation lattice and hardware architecture for motion estimation
(2004-04-01)
Wang, CN
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Yang, SW
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Liu, CM
;
Chiang, TH
;
資訊工程學系
A subsampling structure, an N-Queen lattice, for spatially decimating a block of pixels is presented. Despite its use for many applications, we demonstrate that the N-Queen lattice can be used to speed up motion estimation with nominal loss of coding efficiency. With a simple construction, the N-Queen lattice characterizes the spatial features in the vertical, horizontal, and diagonal directions for both texture and edge areas. Especially in the 4-Queen case, every skipped pixel has the minimal and equal distance of unity to the selected pixel. It can be hierarchically organized for variable nonsquare block-size motion estimation. Despite the randomized lattice, we design compact data storage architecture for efficient memory access and simple hardware implementation. Our simulations show that the N-Queen lattice is superior to several existing sampling techniques with improvement in speed by about N times and small loss in peak SNR (PSNR). The loss in PSNR is negligible for slow-motion video sequences and is less than 0.45 M at worst for high-motion estimation sequences.
A low complexity Picture-in-Picture transcoder for Video-on-Demand
(2005)
Li, CH
;
Wang, CN
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Chiang, TH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The paper presents a low complexity transcoding (LCT) approach with Picture-in-Picture (PIP) functionality based on H.264/AVC standard for Video-on-Demand (VOD) application. To address the high complexity of H.264 decoding and encoding tools, the novel and fast LCT approach composes a PIP frame in the transform domain based on an auxiliary bitstream. The auxiliary bitstream is generated along with the primary bitstream to provide the syntax elements including the transform coefficients and motion information for a rapid frame composition. To balance the transcoding speed and the Rate-Distortion (R-D) performance, the PIP transcoding with the auxiliary bitstream is applied to all inter-coded frames and the partially re-encoding transcoding, is used for the intracoded frames. By removing the high complexity g spatial interpolation, modules including motion compensation, in-the-loop deblocking filter and inverse spatial prediction from the transcoding process of all inter-coded frames, the LCT approach can significantly increase the transcoding throughput with very low memory requirement. Our experimental results show that the R-D performance of the LCT scheme is almost identical to that of the cascaded re-encoding approach, which can provide the theoretical best quality with highest complexity. In addition, the LCT approach that allows users to select the location and size of the foreground frame is applicable to the applications with interactive PIP service.
A new postprocessing method for the block-based DCT coding based on the convex-projection theory
(1998-08-01)
Liu, CM
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Wang, CN
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Lin, JY
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資訊科學與工程研究所
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Institute of Computer Science and Engineering
The block-based DCT coding has been adopted in image compression standards such as JPEG and MPEGs. This type of coding causes some noticeable artifacts known as the blocking effect. Various post processing methods have been devoted to removing the blocking effect; however, these methods also unavoidably blur the decoded image. Removing the blocking effect while avoiding blurring is the main issue of the postprocessing. This paper presents a new postprocessing method based on convex-projection theory. This method is shown to have keep good tradeoff for the blocking effects and the blurring effects.
A novel all binary motion estimation (ABME)
(2002)
Luo, JH
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Wang, CN
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Chiang, TH
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交大名義發表
;
National Chiao Tung University
We present a fast motion estimation algorithm using only binary representation, which is desirable for both embedded system software optimization and hardware implementation with parallel architectures. Our experimental results have showed that it provides excellent performance at both low and high bitrates. Because of its binary only representation, he proposed algorithm offers low computational complexity and low memory bandwidth consumption. For multimedia embedded system design, we further investigated specific implementation technique with an example of Intel x86 processors. Finally we show that binarization methods are closely coupled to the accuracy of binary motion estimation algorithms. The binarization and coding efficiencies can be improved using various filters and binarization methods.
A novel all-binary motion estimation (ABME) with optimized hardware architectures
(2002-08-01)
Luo, JH
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Wang, CN
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Chiang, TH
;
資訊科學與工程研究所
;
電子工程學系及電子研究所
We present a fast motion estimation algorithm using only binary representation, which is desirable for both embedded system and hardware implementation with parallel architectures. The key algorithm distinction is that only the high-frequency spectrum is used. Our experimental results show that it provides excellent performance at both low and high bit rates. Because of its binary-only representation, the proposed algorithm offers low computational complexity and low memory bandwidth consumption. For multimedia-embedded system design, we further investigated specific implementation techniques for several well-known hardware platforms including Intel x86 processors, single-instruction multiple-data processors, and systolic array circuit design. The systolic array architecture requires only single memory access for both the reference and current frames from the on-chip memory. Such an implementation provides an optimized solution with great throughput, while the quality is maintained. Finally, we show that our binarization methods are closely coupled to the accuracy of binary motion estimation algorithms. The binarization and coding efficiencies can be improved using various filters and binarization methods.
A platform-based MPEG-4 Advanced Video Coding (AVC) decoder with block level pipelining
(2003)
Wang, SH
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Peng, WH
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He, YW
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Lin, GY
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Lin, CY
We present a baseline MPEG-4 AVC (Advanced Video Coding) decoder based on an optimized platform-based design methodology. With this methodology, we jointly optimize the software and hardware design of the decoder. Overall decoding throughput is increased by synchronizing the software and the dedicated co-processors. The synchronization is achieved at macroblock-level pipelining. In addition, we optimize the decoder software by enhancing the frame buffer management, boundary padding, and content aware inverse transform. To speed up motion compensation and inverse transform, which are the most computationally intensive modules, two dedicated acceleration modules are realized. For comparison, the proposed prototype decoder and MPEG-4 AVC reference decoder are evaluated on an ARM platform, which is one of most popular portable devices. Our experiments show that the throughput of the MPEG-4 reference decoder can be improved by 6 to 7 times. On an ARM966 board, the optimized software without hardware acceleration can achieve a decoding rate up to 5 frames per second (fps) for QCIF video sequences. With the dedicated accelerators, the overall throughput is increased by about 30% to reach 6.6 fps on the average and is up to 10.3 fps for slow motion video sequences.
A robust fine granularity scalability using trellis-based predictive leak
(2002-06-01)
Huang, HC
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Wang, CN
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Chiang, TH
;
資訊科學與工程研究所
;
電子工程學系及電子研究所
Recently, the MPEG-4 committee has approved the MPEG-4 fine granularity scalability (FGS) profile as a streaming video tool. In this paper, we propose novel techniques to further improve the temporal prediction at the enhancement layer so that coding efficiency is superior to the existing FGS. Our approach utilizes two parameters, the number of bitplanes beta (0 less than or equal to beta less than or equal to maximal number of bitplanes) and the amount of predictive leak alpha (0 less than or equal to alpha less than or equal to 1), to control the construction of the reference frame at the enhancement layer. These parameters alpha and beta can be selected for each frame to provide tradeoffs between coding efficiency and error drift. Our approach offers a general and flexible framework that allows further optimization. It also includes several well-known motion-compensated FGS techniques as special cases with particular sets of alpha and beta. We analyze the theoretical advantages when parameters alpha and beta are used, and provide an adaptive technique to select alpha and beta, which yields an improved performance as compared to that of fixed parameters. An identical technique is applied to the base layer for further improvement. Our experimental results show over 4 dB improvements in coding efficiency using the MPEG-4 testing conditions. The removal of error propagation is demonstrated with several typical channel transmission scenarios.
A robust MPEG-21 media delivery video streaming system
(2004)
Su, TL
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Huang, MY
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Chuang, HC
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Wang, CN
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Chiang, TH
MPEG-21 provides a unified solution, Universal Multimedia Access (UMA), for constructing a multimedia content delivery and rights management framework. Based on the concepts of UMA, we build a simplified UMA model for Internet and over wireless LAN. In this framework, the source video material is encoded and archived as MPEG-4 bitstreams. Moreover, novel intra refresh and error resilience schemes are used to improve the coding efficiency and robustness of the delivered bitstreams. Consequently, the multimedia information can be streamed through the transmission channels with packet losses. The recovered images have insignificant quality degradations for similar streaming systems. To have a more strict evaluation methodology according to the specified common conditions for MPEG-21 media delivery, a unicast streaming system is built on MPEG-21 part-13 Multimedia Test Bed for Resource Delivery. The results show that we can retain significantly improved subjective quality for video streaming over the Internet and wireless channels.
A software-hardware co-implementation of MPEG-4 Advanced Video Coding (AVC) decoder with block level pipelining
(2005-08-01)
Wang, SH
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Peng, WH
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He, YW
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Lin, GY
;
Lin, CY
We present a baseline MPEG-4 Advanced Video Coding (AVC) decoder based on the methodology of joint optimization of software and hardware. The software is first optimized with algorithm improvements for frame buffer management, boundary padding, content-aware inverse transform and context-based entropy decoding. The overall decoding throughput is further enhanced by pipelining the software and the dedicated hardware at macroblock level. The decoder is partitioned into the software and hardware modules according to the target frame rate and complexity profiles. The hardware acceleration modules include motion compensation, inverse transform and loop filtering. By comparing the optimized decoder with the committee reference decoder of Joint Video Team (JVT), the experimental results show improvement on the decoding throughput by 7 to 8 times. On an ARM966 board, the optimized software without hardware acceleration can achieve a decoding rate up to 5.9 frames per second (fps) for QCIF video source. The overall throughput is improved by another 27% to 7.4 fps on the average and up to 11.5 fps for slow motion video sequences. Finally, we provide a theoretical analysis of the ideal performance of the proposed decoder.
A VBR rate control using MINMAX criterion for video streaming
(2002)
Li, CH
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Wang, CN
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Chiang, TH
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資訊工程學系
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電子工程學系及電子研究所
In this paper, we present a frame-level rate control scheme based on a modified linear Rate-Distortion model to achieve minimal maximum (MINMAX) distortion for frame-dependent quantizers. The MINMAX distortion measure is used because the worst visual quality often dominates the overall perceptual quality. In our approach, we first perform the iterative offline analysis of the rate-distortion behavior for the original sequences on a video server. Such compactly stored information enables the encoder to select quantization parameters in real-time during streaming process. Our results show that our algorithm obtains higher minimum PSNR values than the TM5 rate control while the average PSNR is similar. We also use the same technique to optimize statistical multiplexing for a multi-channel transmission application.
Context-based binary arithmetic coding with stochastic bit reshuffling for advanced Fine Granuality Scalability
(2004)
Peng, WH
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Wang, CN
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Chiang, TH
;
Hang, HM
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交大名義發表
We present a novel context based binary arithmetic coding with a stochastic bit-reshuffling scheme to improve bit-plane coding of MPEG-4 Fine Granularity Scalability (FGS). Current approach has not fully considered the correlations across bit-planes and among adjacent transform blocks. To fully exploit correlation, we construct context based on spatial correlation and energy distribution of transform blocks. Furthermore, we consider the context across bit-planes to reduce side information. In addition. when the enhancement-layer is partially decoded, the block update in a raster scan causes unbalanced quality of a decoded frame. To have consistent subjective quality, we reshuffle the bit transmission order with a probability model. Since both encoder and decoder have identical probability model, no extra overhead are required. For faster convergence of statistic adaptation.. we replace the traditional 8 x 8 floating point DCT with 4 x 4 integer transform. As compared to MPEG-4 FGS based bit-plane coding, we can improve the PSNR by 0.5similar to1dB and offer better subjective quality. Specifically, our approach is among top 3 of the Test 1(b) and 1(c) in the subjective quality evaluation of scalable video coding in the 65th MPEG meeting in July 2003.
Effective OHT dispatching for differentiated material handling services in 300mm wafer foundry
(2003)
Wang, CN
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Liao, DY
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工業工程與管理學系
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Department of Industrial Engineering and Management
This paper tackles the problem of providing differentiated material handling services in a highly automated environment of 300mm wafer foundry manufacturing. A preemptive dispatching policy is proposed and studied to expedite the movement of high priority products while keeping the incurred delays on regular ones being acceptable. Simulation experiments based on realistic data from a local 300mm foundry fab are conducted. Numerical results demonstrate that the proposed policy is sound in reducing the transport delay of high priority products to the extreme. Some features of the policy are also explored.
Efficient FGS to single layer transcoding
(2002)
Lin, YC
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Wang, CN
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Chiang, TH
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Vetro, A
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Sun, HF
This paper presents novel architecture for the transcoding of FGS coded video to a single-layer format. Results indicate that the proposed architecture has almost the same performance as the cascaded transcoding method, but with much lower complexity.
Fast motion estimation using N-queen pixel decimation
(2001)
Yang, SW
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Wang, CN
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Liu, CM
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Chiang, TH
;
資訊科學與工程研究所
We present a technique to improve the speed of block motion estimation using only a subset of pixels from a block to evaluate the distortion with minimal loss of coding efficiency. To select such a subset we use a special sub-sampling structure, N-queen pattern. The N-queen pattern can characterize the spatial information in the vertical, horizontal and diagonal directions for both texture and edge features. In the 4-queen case, it has a special property that every skipped pixel has the minimal and equal distance of one to the selected pixel. Despite of the randomized pattern, our technique has compact data storage architecture. Our results show that the pixel decimation of N-queen patterns improves the speed by about N times with small loss in PSNR. The loss in PSNR is negligible for slow motion video sequence and has 0.45 dB loss in PSNR at worst for high motion video sequence.