Yoshiro Tsuboi

A 60 mW MPEG4 video codec using clustered voltage scaling with variable supply-voltage scheme

This MPEG4 video codec implements essential functions in the MPEG4 committee draft. It consumes 60 mW at 30 MHz, 30% of the power dissipation of a conventional CMOS design. Measured power dissipation is summarized. 70% power reduction is achieved by low-power techniques at circuit and architectural levels. A 16b RISC processor provides software programmability. Binary shape decoding uses 20% of the computation power of the RISC processor at 30MHz clock, with negligible increase in chip power dissipation. Three-step hierarchical motion estimation reduces power dissipation.

A 63-mW H.264/MPEG-4 audio/visual codec LSI with module-wise dynamic Voltage/frequency scaling

A single-chip H.264 and MPEG-4 audio-visual LSI for mobile applications including terrestrial digital broadcasting system (ISDB-T / DVB-H) with a module-wise, dynamic voltage/frequency scaling architecture is presented for the first time. This LSI can keep operating even during the voltage/frequency transition, so there is no performance overhead. It is realized through a dynamic deskewing system and an on-chip voltage regulator with slew rate control. By the combination with traditional low power techniques such as embedded DRAM and clock gating, it consumes only 63 mW in decoding QVGA H.264 video at 15 frames/sec and MPEG-4 AAC LC audio simultaneously.

A 160 mW, 80 nA standby, MPEG-4 audiovisual LSI with 16 Mb embedded DRAM and a 5 GOPS adaptive post filter

A single-chip MPEG-4 audiovisual LSI in a 0.13 /spl mu/m 5M CMOS technology with 16 Mb embedded DRAM is presented. Four 16 b RISC processors and dedicated hardware accelerators including a 5 GOPS post filtering engine are integrated on the IC. The chip consumes 160 mW at 125 MHz and uses 80 nA in the standby mode. This LSI handles MPEG-4 CIF video encoding at 15 frames/s and audio encoding simultaneously.

A 9.7mW AAC-Decoding, 620mW H.264 720p 60fps Decoding, 8-Core Media Processor with Embedded Forward-Body-Biasing and Power-Gating Circuit in 65nm CMOS Technology

A AAC-decoding, H.264 decoding, media processor with embedded forward-body-biasing and power-gating circuit in CMOS technology is proposed. Since all the components necessary for the scheme are simple MOS circuits requiring no extra supply voltages, they can be placed and routed by a commercial CAD tool. A data-mapping flip-flop was proposed as a high performance and low-power flip-flop. It is concluded that the power dissipation in H.264 720p 60fps decoding of 620mW at the process fast corner is the lowest among the processor-based solutions.

A single-chip MPEG-2 codec based on customizable media embedded processor

A single-chip MPEG-2 MP@ML codec, integrating 3.8M gates on a 72-mm/sup 2/ die, is described. The codec employs a heterogeneous multiprocessor architecture in which six microprocessors with the same instruction set but different customization execute specific tasks such as video and audio concurrently. The microprocessor, developed for digital media processing, provides various extensions such as a very-long-instruction-word coprocessor, digital signal processor instructions, and hardware engines. Making full use of the extensions and optimizing the architecture of each microprocessor based upon the nature of specific tasks, the chip can execute not only MPEG-2 MP@ML video/audio/system encoding and decoding concurrently, but also MPEG-2 MP@HL decoding in real time.

A process variation compensation scheme using cell-based forward body-biasing circuits usable for 1.2V design

A cell-based forward body-biasing technique to suppress the global process variation and its design flow are proposed. Latch-up free operation is guaranteed by embedded current source cells and limiter cells even when supply voltage is 1.2 V with small area overhead. By applying this technique to a media processor, the worst-case delay is reduced by 20% without sacrificing the maximum leakage spec.

A single-chip MPEG-2 codec based on customizable media microprocessor

A single-chip MPEG2 MP@ML codec, integrating 3.8M gates on a 72mm/sup 2/ die, is described. It has a heterogeneous multiprocessor architecture in which six microprocessors with the same instruction set but different customization execute specific tasks such as video, audio etc. concurrently. The microprocessor, developed for digital media processing, provides various extensions such as a VLIW one and a DSP one inherent in its architecture. Making full use of the extensions, the chip executes encoding and decoding of video, audio and system concurrently in real time.

Design and implementation of scalable, transparent threads for multi-core media processor

In this paper, we propose a scalable and transparent parallelization scheme using threads for multi-core processor. The performance achieved by our scheme is scalable to the number of cores, and the application program is not affected by the actual number of cores. For the performance efficiency, we designed the threads so that they do not suspend and that they do not start their execution until the data necessary for them are available. We implemented our design using three modules: the dependency controller, which controls dependencies among threads, the thread pool, which manages the ready threads, and the thread dispatcher, which fetches threads from the pool and executes them on the core. Our design and implementation provide efficient thread scheduling with low overhead. Moreover, by hiding the actual number of cores, it realizes transparency. We confirmed the transparency and scalability of our scheme by applying it to the H.264 decoder program. With this scheme, modification of application program is not necessary even if the number of cores changes due to disparate requirements. This feature makes the developing time shorter and contributes to the reduction of the developing cost.

A low-power multi-core media co-processor for mobile application processors

A multi-core co-processor for mobile application processors is introduced. It provides low-power, high-throughput, fully software-based acceleration of multimedia processing. The test chip fabricated in a 65nm CMOS technology consumes 620mW in H.264 720p 60fps decoding and 9.7mW in MPEG-4 AAC decoding. In the maximum workload of H.264 decoding, a symmetrical parallelization achieves 7.5× performance enhancement by 8 cores. The shared L2 cache reduces the required rate of main memory access to 310MB/s. In the minimum workload of AAC decoding, three low-power circuit techniques reduce 98% of leakage. On-chip regulators, which also work as power-gating switches, lower the supply voltage of processing cores. Embedded forward body-biasing circuit reduces Vt variations. A low-power and fast data-mapping F/F relaxes the timing constraint, which enables a reduction in the number of low-Vt transistors.