Low Power Depth Estimation of Rigid Objects for Time-of-Flight Imaging

Depth sensing is useful in a variety of applications that range from augmented reality to robotics. Time-of-flight (TOF) cameras are appealing because they obtain dense depth measurements with minimal latency. However, for many battery-powered devices, the illumination source of a TOF camera is power hungry and can limit the battery life of the device. To address this issue, we present an algorithm that lowers the power for depth sensing by reducing the usage of the TOF camera and estimating depth maps using concurrently collected images. Our technique also adaptively controls the TOF camera and enables it when an accurate depth map cannot be estimated. To ensure that the overall system power for depth sensing is reduced, we design our algorithm to run on a low power embedded platform, where it outputs 640x480 depth maps at 30 frames per second. We evaluate our approach on several RGB-D datasets, where it produces depth maps with an overall mean relative error of 0.96% and reduces the usage of the TOF camera by 85%. When used with commercial TOF cameras, we estimate that our algorithm can lower the total power for depth sensing by up to 73%

Rotate Intra Block Copy for Still Image Coding

This paper proposes a method called rotate intra block copy, which extends the intra block copy technique by making the block matching process invariant to rotation. HEVC intra prediction plus rotate intra block copy gives an average of 20% reduction in residual energy (i.e. prediction error) compared to HEVC intra prediction plus intra block copy. As the motion vector correlation in rotate intra block copy is different from the intra block copy, a new method of motion vector coding is presented. The impact of angular resolution on residual energy reduction is also evaluated. In a full codec pipeline, this reduction in residual energy translates into a coding gain in BD-rate of 3.4% over HEVC intra prediction plus intra block copy for both screen content and camera-captured gray scale images.Samsung (Firm). Global Research Outreach Progra

A comparison of CABAC throughput for HEVC/H.265 VS. AVC/H.264

The CABAC entropy coding engine is a well known throughput bottleneck in the AVC/H.264 video codec. It was redesigned to achieve higher throughput for the latest video coding standard HEVC/H.265. Various improvements were made including reduction in context coded bins, reduction in total bins and grouping of bypass bins. This paper discusses and quantifies the impact of these techniques and introduces a new metric called Bjontegaard delta cycles (BD-cycle) to compare the CABAC throughput of HEVC vs. AVC. BD-cycle uses the Bjontegaard delta measurement method to compute the average difference between the cycles vs. bit-rate curves of HEVC and AVC. This metric is useful for estimating the throughput of an HEVC CABAC engine from an existing AVC CABAC design for a given bit-rate. Under the common conditions set by the JCT-VC standardization body, HEVC CABAC has an average BD-cycle reduction of 31.1% for all intra, 24.3% for low delay, and 25.9% for random ac-cess, when processing up to 8 bypass bins per cycle

Joint Algorithm-Architecture Optimization of CABAC

This paper uses joint algorithm and architecture design to enable high coding efficiency in conjunction with high processing speed and low area cost. Specifically, it presents several optimizations that can be performed on Context Adaptive Binary Arithmetic Coding (CABAC), a form of entropy coding used in H.264/AVC, to achieve the throughput necessary for real-time low power high definition video coding. The combination of syntax element partitions and interleaved entropy slices, referred to as Massively Parallel CABAC, increases the number of binary symbols that can be processed in a cycle. Subinterval reordering is used to reduce the cycle time required to process each binary symbol. Under common conditions using the JM12.0 software, the Massively Parallel CABAC, increases the bins per cycle by 2.7 to 32.8× at a cost of 0.25 to 6.84% coding loss compared with sequential single slice H.264/AVC CABAC. It also provides a 2× reduction in area cost, and reduces memory bandwidth. Subinterval reordering reduces the critical path delay by 14 to 22%, while modifications to context selection reduces the memory requirement by 67%. This work demonstrates that accounting for implementation cost during video coding algorithms design can enable higher processing speed and reduce hardware cost, while still delivering high coding efficiency in the next generation video coding standard.Texas Instruments Incorporated (Graduate Women's Fellowship for Leadership in Microelectronics)Natural Sciences and Engineering Research Council of Canad

A Deeply Pipelined CABAC Decoder for HEVC Supporting Level 6.2 High-tier Applications

High Efficiency Video Coding (HEVC) is the latest video coding standard that specifies video resolutions up to 8K Ultra-HD (UHD) at 120 fps to support the next decade of video applications. This results in high-throughput requirements for the context adaptive binary arithmetic coding (CABAC) entropy decoder, which was already a well-known bottleneck in H.264/AVC. To address the throughput challenges, several modifications were made to CABAC during the standardization of HEVC. This work leverages these improvements in the design of a high-throughput HEVC CABAC decoder. It also supports the high-level parallel processing tools introduced by HEVC, including tile and wavefront parallel processing. The proposed design uses a deeply pipelined architecture to achieve a high clock rate. Additional techniques such as the state prefetch logic, latched-based context memory, and separate finite state machines are applied to minimize stall cycles, while multibypass- bin decoding is used to further increase the throughput. The design is implemented in an IBM 45nm SOI process. After place-and-route, its operating frequency reaches 1.6 GHz. The corresponding throughputs achieve up to 1696 and 2314 Mbin/s under common and theoretical worst-case test conditions, respectively. The results show that the design is sufficient to decode in real-time high-tier video bitstreams at level 6.2 (8K UHD at 120 fps), or main-tier bitstreams at level 5.1 (4K UHD at 60 fps) for applications requiring sub-frame latency, such as video conferencing

Eyeriss v2: A Flexible Accelerator for Emerging Deep Neural Networks on Mobile Devices

A recent trend in DNN development is to extend the reach of deep learning applications to platforms that are more resource and energy constrained, e.g., mobile devices. These endeavors aim to reduce the DNN model size and improve the hardware processing efficiency, and have resulted in DNNs that are much more compact in their structures and/or have high data sparsity. These compact or sparse models are different from the traditional large ones in that there is much more variation in their layer shapes and sizes, and often require specialized hardware to exploit sparsity for performance improvement. Thus, many DNN accelerators designed for large DNNs do not perform well on these models. In this work, we present Eyeriss v2, a DNN accelerator architecture designed for running compact and sparse DNNs. To deal with the widely varying layer shapes and sizes, it introduces a highly flexible on-chip network, called hierarchical mesh, that can adapt to the different amounts of data reuse and bandwidth requirements of different data types, which improves the utilization of the computation resources. Furthermore, Eyeriss v2 can process sparse data directly in the compressed domain for both weights and activations, and therefore is able to improve both processing speed and energy efficiency with sparse models. Overall, with sparse MobileNet, Eyeriss v2 in a 65nm CMOS process achieves a throughput of 1470.6 inferences/sec and 2560.3 inferences/J at a batch size of 1, which is 12.6x faster and 2.5x more energy efficient than the original Eyeriss running MobileNet. We also present an analysis methodology called Eyexam that provides a systematic way of understanding the performance limits for DNN processors as a function of specific characteristics of the DNN model and accelerator design; it applies these characteristics as sequential steps to increasingly tighten the bound on the performance limits.Comment: accepted for publication in IEEE Journal on Emerging and Selected Topics in Circuits and Systems. This extended version on arXiv also includes Eyexam in the appendi

An Energy-Efficient Hardware Implementation of HOG-Based Object Detection at 1080HD 60 fps with Multi-Scale Support

A real-time and energy-efficient multi-scale object detector hardware implementation is presented in this paper. Detection is done using Histogram of Oriented Gradients (HOG) features and Support Vector Machine (SVM) classification. Multi-scale detection is essential for robust and practical applications to detect objects of different sizes. Parallel detectors with balanced workload are used to increase the throughput, enabling voltage scaling and energy consumption reduction. Image pre-processing is also introduced to further reduce power and area costs of the image scales generation. This design can operate on high definition 1080HD video at 60 fps in real-time with a clock rate of 270 MHz, and consumes 45.3 mW (0.36 nJ/pixel) based on post-layout simulations. The ASIC has an area of 490 kgates and 0.538 Mbit on-chip memory in a 45 nm SOI CMOS process.Texas Instruments IncorporatedUnited States. Defense Advanced Research Projects Agency (Young Faculty Award Grant N66001-14-1-4039