Scalable high performance loop filter architecture for video codecs
There is continuous thrust on improved and innovative video solution to facilitate video conferencing, video surveillance, transcoding, streaming video and many more customer centric new solutions. Increasing frame rate and frame size demands high performance hardware accelerators (HWA) to enable efficient 16×16 pixels macroblock level (MB) pipelining inside video processing engine (IVAHD). Inloop de-blocking filter of H.264 codec reduces blocking artifacts in MB and it is very demanding in terms of cycles and resources (memory access and memory storage). Removal of blocking artifacts due to block-based video codecs takes around 20-25% of overall decoder complexity in current generation of standards (H.264) and trend will continue going forward in H.265. Higher adaptability of filter process, smaller block sizes (4×4), motion vector (MV) dependent boundary strength (BS) computation for each edge of 4×4 block, predefined order for doing filtering (vertical edge followed by horizontal edge) and data pixel loading of current and neighbor MB requires large number of accesses to shared memory of IVAHD (SL2), higher processing cycles and larger internal pixel buffer (IPB). This paper discusses novel approach of loop filter (LPF) operation to overcome above barriers and facilitate IVAHD to go up to 240fps frame rate in full HD processing of H.264 codec with leadership area and power. The final design in 28nm CMOS process is expected to take around 0.10 mm2 after actual place and route (consisting of 220 KGate with 5 KB of internal memory). Proposed design is capable of handling 4K@60fps and scalable to support H.265 inloop de-blocking filter.
Customization of de-blocking filter edge order for high performance: Study of H.264 AVC/SVC, H.265
Transformation and quantization in block based video codecs introduces blocking artifacts at edges. Special optimized video filter called de-blocking filter is applied on 4×4/8×8 block boundary to enhance visual quality and improve prediction efficiency. Most of the recent video codecs, H.264, H.265 (HEVC), VC-1 uses in-loop de-blocking (LPF) filter in decoder path. Each video codec standard defines fixed order of filter operation to have consistency in universal decoder output. Standard defined fixed edge order is not optimal for various architectures of de-blocking Hardware Accelerator (HWA), as it will have to compromise on performance, power or area. Pipelining of unfiltered pixel loading with filter operation, internal storage to keep partially or fully filtered pixels and order of storage of fully filtered pixels are some of the challenges that are difficult to meet with standard defined edge order. In this paper, a novel approach of customizing edge order is discussed for differing architectural requirements and for various video codec standards. Resultant filtered data with optimized edge order matches that of with standard defined edge order.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.