• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.1040-1057
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• 2014

In this paper, a new bit rate estimation scheme is proposed to determine the bit rate for each subclass in an MPEG-2 TS to H.264/AVC transcoder after dividing an input MPEG-2 TS sequence into several subclasses. Video format transcoding in conventional IPTV and Smart TV services is a time-consuming process since the input sequence should be fully transcoded several times with different bit-rates to decide the bit-rate suitable for a service. The proposed scheme can automatically decide the bit-rate for the transcoded video sequence in those services which can be stored on a video streaming server as small as possible without losing any subject quality loss. In the proposed scheme, an input sequence to the transcoder is sub-classified by hierarchical clustering using a parameter value extracted from each frame. The candidate frames of each subclass are used to estimate the bit rate using a statistical analysis and a mathematical model. Experimental results show that the proposed scheme reduces the bit rate by, on an average approximately 52% in low-complexity video and 6% in high-complexity video with negligible degradation in subjective quality.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.297-310
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• 2013

In this paper, we present a model-based video bit rate estimation scheme for reducing the bit rate while maintaining a subjective quality in many video streaming services limited by network bandwidth, such as IPTV services. First, we extract major parameters which serve as an indirect measurement of frame's bits. Using those parameters, the proposed bit rate estimation scheme can extract candidate frames. Finally, the bit rate of each segment is estimated by statistical analysis and a mathematical model based on a given target quality. In experimental results, we show that the proposed scheme can reduce the bit rate on average by 43% in low-complexity video while maintaining the subjective quality. To find the appropriate bit rate based on video contents, the proposed schemes can estimate the bit rate with neither the repeated full encoding nor subjective quality test. On average, the bit rate can be automatically estimated by encoding the candidate frames of 4%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.10
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• pp.1814-1829
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• 2011

In this paper, we present a model-based video bit rate estimation scheme for reducing the bit rate while maintaining a given target quality in many video streaming services limited by network bandwidth, such as IPTV services. Each item of video content can be stored on a video streaming server and delivered with the estimated bit rate using the proposed scheme, which consists of the following two steps: 1) In the first step, the complexity of each intra-frame in a given item of video content is computed as a frame feature to extract a group of candidate frames with a lot of bits. 2) In the second step, the bit rate of the video content is determined by applying statistical analysis and hypothesis testing to that group. The experimental results show that our scheme can reduce the bit rate by up to 78% with negligible degradation of subjective quality, especially with the low-complexity videos commonly used in IPTV services.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.301-304
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• 2014

This paper proposes accurate interference probability and bit error rate formulas for cognitive relay networks with underlay spectrum sharing and channel estimation error (CEE). Numerous results reveal that the CEE not only degrades the performance of secondary systems (SSs) but also increases interference power caused by SSs to primary systems (PSs), eventually unfavorable to both systems. A solution to further protect PSs from this effect through reducing the power of secondary transmitters is investigated and analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1C
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• pp.34-44
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• 2008

In this paper, a new rate-distortion estimation method is proposed for fast rate-distortion optimized(RDO) mode decision in H.264 encoder. A bit-rate and distortion should be calculated by encoding and reconstruction of each macroblock mode in order to select the optimal RDO mode. To reduce the computations for getting them, a bit-rate and distortion is efficiently estimated in DCT domain. Simulation results show that the proposed method achieves computational saving about 81% of RDO mode decision and saves about 26% of total encoding time without noticeable degradation in coding performance.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.745-747
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• 1999

디지털 TV의 동영상 표준인 MPEG2는 방대한 양의 디지털 데이터를 발생한다. 그러나 현재 사용하고 있는 디지털 저장 매체의 수용 능력에는 한계가 있으므로 저장을 위해 전송된 high bit rate의 MPEG2 bitstream을 더욱 낮은 bit rate의 bitstream으로 전환하는 transcoding 기법이 반드시 필요하다. 기존의 encoder와 decoder를 이용하여 구현 가능한 장점이 있는 cascade transcoder는 reencoding시 motion estimation에 많은 수행 시간이 소요되므로, motion estimation 과정을 최소화하면서 optimal motion vector를 구할 수 있는 motion vector refinement 기법을 MPEG2 cascade transcoder에 적용하였다. 결과 처리 속도는 3-5배 향상되었고 화질은 기존의 72 transcoder에 비해 평균 0.1dB 이상의 FSNR 향상이 있었다. 또한 1Mbps와 같은 low bit rate에서 더욱 큰 화질 향상이 있었다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2629-2639
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• 1997

The video coding for very low bit-rate has recently received considerable attention, but the conventional coding schemes with block based transform suffer from the blocky effect for the constraints of limited bit-rate. In this paper, we present a video coding system based on wavelet transform and multiresolution motion estimation/compensation for very low bit-rate video. The proposed scheme uses the wavelet transform which is flexible to represent non-stationary image signals and adaptable to the human visual characteristics. The wavelet transformed coefficients are coded by various coding modes in accordance with the sum of absolute error after motion estimation/compensation in wavelet decomposed domain. And simple buffer control technique is applied to handle constant image quality. It is shown that the presented scheme has more acceptable image quality without blocky effects than conventional block based transform video coding.

• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.410-418
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• 2022

Channel reliability estimation for iterative codes such as turbo codes is very important factor in time varying underwater acoustic channel, an incorrect estimation of channel reliability induced performance degradation. Therefore, this paper presents an optimal channel reliability estimation method for turbo coded FSK signal with rate of 1/3. The estimated BER algorithm is a method that can estimate the reliability of received data by comparing received data and decoded data, and we determine optimal channel reliability by using the method. In order to analyze the performance, the experiment was conducted on a lake in Munkyeong city by moving in the range of 300 m to 500 m. At the result of applying presented method to failed decoding packets, we confirm all packets are decoded successfully.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4E
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• pp.24-30
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• 2001

This paper describes a fast harmonic estimation, referred to as Delta Adjustment (DA), using a low resolution pitch. The presented DA method is based on modification of the Generalized Dual Excitation (GDE) technique[1] which was proposed to improve speech enhancement performance. We introduce the GDE technique and modify it to be suitable for low bit rate harmonic coding that uses only an integer pitch estimate. Unlike the GDE, the DA matches a frequency-warped version of the original spectrum that conforms to a fixed pitch at all harmonic bands. In addition, complexity and performance of the presented method are described in comparison with those of the conventional Fractional Pitch (FP) based harmonic estimation. Experimental results showed that the DA algorithm significantly reduces the complexity of the FP method while maintaining the performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7C
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• pp.548-553
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• 2008

To reduce the bit-rate requirements imposed by a network or satisfy processing limitations imposed by a terminal, Conversion the temporal resolution of a video bit stream is a technique that may be used. This paper discusses the problem of reduced resolution transcoding of compressed video bit streams, and discussed the technique for temporal transcoding. To speed up this operation, a video transcoder usually reuses the coded motion vectors from the input video bit stream. In this paper we propose an enhanced motion re-estimation technique to maintain higher quality of coded frames. The performance of experimental results can be improved while maintaining low computational complexity for a reduced frame rate video transcoder.