In order to speed up the encoding process of HEVC, there have been many fast encoding methods proposed to reduce the number of CUs and PUs. Besides, the early TU decision algorithm (ETDA) is another method selected to reduce the encoding complexity of TU. Recently, Chio et al. proposed a new ETDA by determining the number of nonzero DCT coefficients (NNZ) of RQT (called NNZ-EDTA) to accelerate the encoding process of TU module [6]. However, the NNZ-ETDA can't effectively reduce the computational load for sequences with active motion or rich texture. Therefore, in order to further improve the performance of NNZ-ETDA, we propose an adaptive RQT depth for NNZ-ETDA (called ARD-NNZ-ETDA) by exploiting the characteristics of high temporal-spatial correlation exists in nature video sequences. An adaptive depth of RQT is employed to the NNZ-ETDA to further reduce the computational load of TU. Simulation results show that the proposed method can achieve time improving ratio (TIR) about 61.26%~81.48% when compared to HEVC (HM 8.1) with insignificant loss of image quality. Compared with the NNZ-ETDA, the proposed method can further achieve an average TIR about 8.29%~17.92%.
In this paper, we propose an embedded real-time H.264 Baseline Profile (BP) decoder based on ADSP-BF548 Blackfin processor. In order to achieve the real-time requirement of H.264 decoding, we modify and optimize the decoding modules and codes, respectively. Firstly, we analyze the number of operations for various modules using assembly code, and then use direct memory access (DMA) to carry out the parallelism between algorithm execution and data movement. Finally, we make use of two buffer groups (BG) as parallel decoding mechanism of broadcast transformation. Experimental results demonstrate that the play rate can reach above 25 fps as using QCIF video. According to some tests, a real-time H.264 BP decoding can be achieved with a 600 MHz DSP.
In this paper, a high-speed H.264 encoder based on ADI BF548 Blackfin DSP is proposed. In order to speed up the process of motion estimation (ME) module in H.264, we propose a two-step bit-transform-based normalized partial distortion search (TSB-NPDS) algorithm for fast ME by using the characteristics of pattern similarity matching errors. An initial standard compliant raw-C encoder has been optimized in speed for target processor. In addition, the parallelism between algorithm execution and data movement has been fully exploited using DMA. Experimental results demonstrate that the encoding rate can reach above 30 fps as using QCIF video.
In this paper, we develop a novel robust scheme of two-dimensional unequal error protection (2-D UEP) for the H.264 scalable video coding (SVC) with a combined temporal and quality (SNR) scalability over packet-erasure channel. To avoid the waste of bits and obtain the best rate allocation, we propose a threshold-based UEP (TH-UEP) scheme. The proposed TH-UEP designs a predefined threshold according to the length of packet and the error correcting ability of RS code to achieve the best allocation. In addition, the proposed scheme also derives a simple mathematical model to reduce computational load of the best allocation. Experimental results demonstrate that the proposed H.264 video transmission scheme can provide strong robustness and video quality improvement when compared to other 2-D UEP schemes.
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