Yi-Hau Chen

Level C+ data reuse scheme for motion estimation with corresponding coding orders

The memory bandwidth reduction for motion estimation is important because of the power consumption and limited memory bandwidth in video coding systems. In this paper, we propose a Level C+ scheme which can fully reuse the overlapped searching region in the horizontal direction and partially reuse the overlapped searching region in the vertical direction to save more memory bandwidth compared to the Level C scheme. However, direct implementation of the Level C+ scheme may conflict with some important coding tools and then induces a lower hardware efficiency of video coding systems. Therefore, we propose n-stitched zigzag scan for the Level C+ scheme and discuss two types of 2-stitched zigzag scan for MPEG-4 and H.264 as examples. They can reduce memory bandwidth and solve the conflictions. When the specification is HDTV 720p, where the searching range is [-128,128), the required memory bandwidth is only 54%, and the increase of on-chip memory size is only 12% compared to those of traditional Level C data reuse scheme.

A 59.5mW scalable/multi-view video decoder chip for Quad/3D Full HDTV and video streaming applications

With advances in video coding technology, two main streams of multimedia applications are emerging. The first involves more vivid perceptual experience and is leading to the next generation of TV specifications - Quad Full HD (QFHD, 4096×2160p) and 3D/multi-view TV. The second is the scalable broadcasting and streaming of video.

An H.264/AVC scalable extension and high profile HDTV 1080p encoder chip

The first single-chip H.264/AVC HDTV 1080 p encoder for scalable extension (SVC) with high profile is implemented on a 16.76 mm2 die with 90 nm process. It dissipates 349/439 mW at 120/166 MHz for high profile and SVC encoding. The proposed frame-parallel architecture halves external memory bandwidth and operating frequency. Moreover, the prediction architecture with inter-layer prediction tools are applied to further save 70% external memory bandwidth and 50% internal memory access.

Bandwidth-efficient cache-based motion compensation architecture with DRAM-friendly data access control

For H.264/AVC decoder system, the motion compensation bandwidth comes from two parts, the reference data loading bandwidth and the equivalent bandwidth from DRAM access overhead latency. In this paper, a bandwidth-efficient cache-based MC architecture is proposed. It exploits both intra-MB and inter-MB data reuse and reduce up to 46% MC bandwidth compared to conventional scheme. To reduce the equivalent bandwidth from DRAM access overhead latency, the DRAM-friendly data mapping and access control scheme are proposed. They can reduce averagely 89.8% of equivalent DRAM access overhead bandwidth. The average MC burst length can be improved to 9.59 words/burst. The total bandwidth reduction can be up to 32∼71% compared to previous works.

System Analysis of VLSI Architecture for 5/3 and 1/3 Motion-Compensated Temporal Filtering

Motion-compensated temporal filtering (MCTF) is an innovative prediction scheme for video coding and it has become the core technology of the coming video coding standard, Scalable Video Coding. Since MCTF is important, this paper provides the system analysis of MCTF for hardware architecture design, including computational complexity, external memory bandwidth, and external memory size. The one-level MCTF is analyzed first, in which several frame-level data reuse schemes are proposed and the tradeoffs between external memory usages and on-chip memory size in these frame-level data reuse schemes are also discussed. Next, the analysis is extended to multilevel MCTF. The computational complexity of multilevel MCTF is close to that of traditional MC prediction with two reference frames. The memory bandwidth of multilevel MCTF depends on the frame-level data reuse scheme and performing the update stage or not. The external memory size is linearly proportional to the number of decomposition levels. Finally, a real-life test case is given to compare the system requirements between MCTF with various frame-level data reuse schemes and the prediction scheme of H.264/AVC

Frame-parallel design strategy for high definition B-frame H.264/AVC encoder

High Definition (HD) H.264/AVC video compression is the emerging necessity on nowadays home entertainment environment and so on. However, Although B-frame coding scheme provides better quality, only P-frame encoders are presented due to too high complexity and memory requirement. In this paper, a frame-parallel encoding scheme based on B-frames data independency is proposed. It can largely reduce the system memory bandwidth and improve the processing capability. Then, the proposed IME and FME scheduling can further enhance the hardware utilization for frame-parallel scheme. Finally, a case study is given to show that the proposed scheme can largely reduce 66% system bandwidth compared to direct implementation from previous P-frame encoder.

Efficient Architecture Design of Motion-Compensated Temporal Filtering/Motion Compensated Prediction Engine

Since motion-compensated temporal filtering (MCTF) becomes an important temporal prediction scheme in video coding algorithms, this paper presents an efficient temporal prediction engine which not only is the first MCTF hardware work but also supports traditional motion-compensated prediction (MCP) scheme to provide computation scalability. For the prediction stage of MCTF and MCP schemes, modified extended double current Frames is adopted to reduce the system memory bandwidth, and a frame-interleaved macroblock pipelining scheme is proposed to eliminate the induced data buffer overhead. In addition, the proposed update stage architecture with pipelined scheduling and motion estimation (ME)-like motion compensation (MC) with level C+ scheme can also save about half external memory bandwidth and eliminate irregular memory access for MC. Moreover, 76.4% hardware area of the update stage is saved by reusing the hardware resources of the prediction stage. This MCTF chip can process CIF 30 fps in real-time, and the searching range is [-32, 32) for 5/3 MCTF with four-decomposition level and also support 1/3 MCTF, hierarchical B-frames, and MCP coding schemes in JSVM and H.264/AVC. The gate count is 352-K gates with 16.8 KBytes internal memory, and the maximum operating frequency is 60 MHz.

Low bandwidth decoder framework for H.264/AVC scalable extension

In the process of scalable video coding (SVC) decoding, large external memory bandwidth is required for SVC inter-layer prediction. In this paper, a low bandwidth decoder framework is proposed for SVC. Two main decoding schemes are developed to reduce the external memory bandwidth. Macroblock-level on-the-fly padding and on-line upsampling is proposed for SVC spatial scalability decoding. This scheme reduces 36% of decoding bandwidth and 34% of processing cycles. For SVC quality scalability, a layer-interleaving decoding scheme is proposed to eliminate all inter-layer prediction bandwidth which is 41–51% of decoding bandwidth. The corresponding hardware architectures of these two decoding schemes are also provided. This low bandwidth framework can save 33–52% of DRAM access power for SVC decoding.

Unsupervised object-based sprite coding system for tennis sport

Sprite coding is a new objected-based coding technology proposed by MPEG-4 video standard. In this paper, we propose an unsupervised sprite coding system for sport videos, for example, tennis sequences. Our system can provide several important functions. First, the sprite of the background can be generated without any pre-processing masks in our system. Second, it can automatically segment the foreground and background in a video sequence. Third, it can provide the masks of the foreground objects and the tennis ball. The experimental results show that our system has a very good performance and the coding gain of our system compared with MPEG-4 advanced simple profile is 2.5 dB at the low bit rate (270 Kbps) and is 2 dB at the ultra low bit rate (70 Kbps). It can be used in the sport video coding at low bit rate and provides a object-based sport video sequence.

Frame-level data reuse for motion-compensated temporal filtering

Motion-compensated temporal filtering (MCTF) is an open-loop prediction scheme, so the frame-level data reuse for MCTF is possible. In this paper, we propose two general frame-level data reuse schemes which can minimize the memory bandwidth of current and reference frames, respectively. And their relationships between the required memory bandwidth and the number of searching range buffers are also formulated under the constraint of the data dependency in joint scalable video model. Finally, we extend our analysis to pyramid MCTF and the impact of the inter-layer prediction scheme is also considered